Plants are subject to attack and infection by a variety of pests and pathogens as they grow, and have evolved sophisticated and complex defense systems in response to pathogen invasions, which can trigger specific transcription factors for effective immune responses through multiple signaling pathways. The AP2/ERF (APETALA2/ethylene response factor) family members play important roles as plant-specific transcription factors in plant growth, development and biotic and abiotic stress responses. In this review, we summarized the classification, structural features, sequence recognition and functions of AP2/ERF transcription factors by referring to the relevant research progress in recent years at home and abroad, and focused on those of AP2/ERF transcription factors involved in plant disease resistance in the areas of transcriptional regulation, post-translational modification-phosphorylation regulation, secondary metabolite synthesis and hormone signaling. It provides a theoretical reference for the in-depth study of the regulation mechanism of AP2/ERF involved in plant disease resistance. Finally, the research and application prospects of AP2/ERF were discussed and prospected.

The occurrence of potyviruses and poleroviruses in vegetable crops is common, and seriously affects quality and yield. In order to develop environmental friendly and efficient plant virus inhibitors, potyviruses and poleroviruses were detected and analyzed using RT-PCR in suspected virus disease samples of vegetable crops such as Capsicum annuum, Solanum lycopersicum, Cucurbita moschata, Cucurbita pepo, Phaseolus vulgaris and Vigna unguiculata in Luoyang city. The results showed that the main viruses were pepper vein yellows virus (PeVYV) in pepper, potato virus Y (PVY) in tomato, and zucchini yellow mosaic virus (ZYMV) and cucurbit aphid-borne yellows virus (CABYV) in pumpkin and zucchini. Co-infection with ZYMV and CABYV was common. In kidney beans, melon aphid-borne yellows virus (MABYV) was detected, while no virus was detected in cowpea samples. Among them, the occurrence of ZYMV in pumpkin and zucchini was more serious, and kidney bean was found as a new natural host of MABYV for the first time. The phylogenetic analysis showed that the PVY-LYFQ isolate obtained in this study had a relatively distant relationship with other PVY isolates, and the genetic variability of PVY isolates was not closely related to their geographic locations or hosts, as well as the genetic variability of PeVYV isolates was not directly related to their geographic locations, but was related to their hosts to some extent; the genetic variability of ZYMV isolates were related to both their geographic locations and hosts to some extent; the genetic variability of CABYV and MABYV genome sequences was all related to their geographic locations. This study provides an important theoretical basis for the prevention and monitoring of potyviruse and poleroviruse diseases, the implementation of control measures, and the development of control drugs in vegetable crops in the Luoyang area.

The tomato leaves and fruits suspected to be infected with tomato brown rugose fruit virus (ToBRFV) were collected from the tomato planting area in Chifeng City, Inner Mongolia, in March 2024. RT-PCR technology was employed to amplify approximately 798 bp sequence with degenerate primers ToBRFV-MP-F/R to detect the presence of TOBRFV in this study. Furthermore, based on the sequencing results, the complete genome sequence of ToBRFV-NMG was obtained using four pairs of specifically designed primers. BLAST comparison showed that the cloned ToBRFV-NMG complete genomic nucleotide sequence shared the highest identity (99.86%) with the Shandong isolate of ToBRFV (ToBRFV-SD, GenBank accession number: MT018320). Phylogenetic trees showed that the genome sequence of the newly isolated ToBRFV-NMG was most closely related to the ToBRFV-SD isolate reported in Shandong in 2020. Both of them were clustered in the same branch, and they were also closely related to other isolates of Tobamovirus as well. Pathogenicity analysis showed that the virus infected tomato leaf was able to infect Nicotiana benthamiana, Capsicum annuum L., and Solanum lycopersium resulting in symptoms such as wrinkling, mosaic and necrosis that are consistent with those observed in the field. The viral sequence was determined by RT-PCR and was identical to the sequence of ToBRFV-NMG. These results confirm that the tomato fruits and leaves were infected by a ToBRFV isolate. This is the first report of tomato infected by ToBRFV in Inner Mongolia, which sheds light on the identification, prevention and control of local viral diseases.

To investigate the causal agent of leaf blight occurred on Picea asperata Mast, diseased samples were collected in Dalian, Liaoning Province, and tissue isolation was performed. The pathogenicity of the representative isolates was verified by Koch′s postulates. The pathogen was identified as Nothophoma quercina according to morphological characteristics and multi-gene (ITS, RPB2, TUB2, and LSU)-based phylogenetic analysis result. The growth of N. quercina on different culture media, carbon sources, nitrogen sources, tempera-tures, light conditions, and pH values was determined. The results showed that N. quercina grew best on SDA culture medium, with soluble starch as carbon source and urea as nitrogen source, at 25°C, pH 7.0, and a 12 h light/12 h dark cycle. Ten pesticides were tested for their in vitro antifungal activity against N. quercina, and 98% pyraclostrobin TC showed the best inhibitory effect, with an EC₅₀ value of 0.0196 μg·mL^-1. Five pesticides with higher inhibitory effects were selected for further field efficacy trials. It was showed that the best control effect was achieved by using 250 g·L^-1 pyraclostrobin EC, with an efficacy of over 65% in July and September. The results lay a basis for further investigating the occurrence regularity and chemical control of the disease.

In the study, a metacaspases gene was islated from the cDNA library of the interaction between the wheat cultivar ‘Suwon 11’ and Puccinia striiformis West. f. sp. tritic Eriks.＆ Henn.(Pst). The gene was designed as TaMCA3. Through transient overexpression experiments, it was found that the TaMCA3 gene can effectively inhibit cell necrosis induced by the cell necrosis inducer BAX. The protoplast subcellular localization experiment showed that the TaMCA3 protein is mainly distributed in the cytoplasm. During the compatible interaction between wheat and Pst, it is shown that TaMCA3 participates in the susceptibility process of wheat to Pst. After using VIGS (virus-induced gene silence) technology to transiently silence TaMCA3, in comparison to the control plants, the silenced plants exhibited obvious necrotic spots on their leaves, and the number of urediniospore pustules of Pst CYR31 was significantly reduced. This indicates that silencing TaMCA3 can significantly enhance wheat′s resistance to Pst CYR31. Furthermore, by using yeast two-hybrid screening identified TaASP, a left-handed aspartate protease, was identified as the interacting target of TaMCA3. In vitro and in vito protein interaction experiments confirmed the interaction between TaASP and TaMCA3. This discovery provides new insights for a deeper understanding of the specific functions and mechanisms of TaMCA3 in the interaction between wheat and Pst.

Sexual reproduction is important in the disease cycle and life history of Villosiclava virens. V. virens is a heterothallic fungus. The distribution of mating-type populations is directly related to the frequency of the occurrence of the sexual reproduction of V. virens in the field. It is a critical guideline for the early warning and disease control of rice false smut. To clarify the distribution of the mating type population of V. virens in Jiangsu Province, 255 strains of V. virens that collected and isolated in Jiangsu Province in 2023 and 2024 were employed for the mating type detection of the pathogen population in this study. The results of the polymerase chain reaction (PCR) demonstrated that the MAT1-1 mating group was the predominant strain in ten distinct regions of Jiangsu Province. The ratio of MAT1-1 to MAT1-2 mating strains was 1.71, indicating a deviation in the genetic composition of the mating types. Further analysis of the virulence of the different mating type populations revealed that the MAT1-1 type was significantly more pathogenic than the MAT1-2 type. Subsequently, using Wilcoxon analysis, a significant correlation was found between virulence and the mating types, suggesting that there may be a divergence of virulence between the different mating type populations of MAT1-1 and MAT1-2 among the V. virens. A comparison of the distribution characteristics of mating type populations in different areas of Jiangsu Province in 2023 and 2024 revealed that, in addition to sexual reproduction and virulence, the structure of mating type populations of V. virens may also be influenced by asexual reproduction. Overall, this study represents the comprehensive investigation into the mating population distribution characteristics of V. virens in Jiangsu Province and the virulence differentiation among mating populations of different mating types. Our findings suggest that both sexual and asexual reproduction play significant roles in the evolution of V. virens mating populations and the dynamics of the infection cycle of the disease.

Phytoalexins are secondary metabolites induced by pathogens in plants and have broad-spectrum disease resistance and species specificity. Phytoalexins play an indispensable role in enhancing crop yield and ensuring crop quality. Terpenoid phytoalexins include sesquiterpenes, diterpenes and triterpenes. The biosynthetic pathways of most terpenoid phytoalexins are currently elucidated. Gene clusters or strings responsible for terpenoid phytoalexins biosynthesis are found, and genes in a cluster are co-regulated and co-responsive. Multiple regulatory factors of the terpenoid phytoalexins have been reported. This review aims to summarize the recent progress of the metabolic regulatory mechanism of terpenoid phytoalexins, including the biosynthetic pathways and regulatory factors. The prospects of terpenoid phytoalexins for resistance breeding and sustainable prevention and control of plant diseases are discussed.

To clarify the distribution of tobacco root-knot nematode in the Huang-Huai tobacco growing region, a comprehensive survey was conducted from 2018 to 2023. The study covered 120 tobacco-growing areas across 12 key cities in four provinces within the Huang-Huai tobacco-growing region of China. The nematode species were identified using combination of morphological and molecular biology methods. The results indicated that widespread distribution of root-knot nematodes in the Huang-Huai tobacco region, with Meloidogyne incognita being the predominant species in the southern region. Additionally, M. arenaria, M. hapla and M. javanica were found in some local areas, albeit on a small scale. Among the surveyed 120 tobacco-growing areas, M. incognita were detected in 109 areas (90.83% detection rate), M. arenaria in 32 areas (26.67%), M. hapla in 8 areas (6.67%), and M. javanica in 3 areas (2.50%). Notably, severe mixed population of M. incognita were observed in some areas, including 18 tobacco-growing regions with co-infection by M. incognita and M. arenaria (15.00%), 5 regions with co-infection by M. hapla(4.17%), and 3 regions with triple co-infections of M. incognita and M. arenaria (2.50%). Furthermore, the isolation and identification of second stage juveniles (J2s) of soil root knot nematodes revealed that the average highest concentration of J2s was found in tobacco fields soil from Pingdingshan, with 465.74 J2s per 100 mL of soil. The quantity of J2s in tobacco fields soil from Nanyang and Luoyang regions were 398.17 and 276.79 J2s per 100 mL soil, respectively. The study also found a significant correlation between severe infestations of tobacco root-knot nematode and the occurrence of root and stem fungal diseases, both of which were prevalent in these areas. The investigation provides a comprehensive understanding of the distribution of tobacco root-knot nematodes in the Huang-Huai tobacco growing region, highlighting their role as a major threat to tobacco production. The research results contribute valuable data to monitoring, early warning systems, and management strategies for controlling tobacco root-knot nematode disease in China. Finally, this study offers critical insights into the population dynamics of Meloidogyne species in the country, establishing a strong theoretical and empirical foundation for future research and pest management strategies.

To explore the genetic patterns of Puccinia striiformis f. sp. tritici (Pst) populations in Qinghai Province, China, in this study, wheat leaves infected by Pst from various regions and at different infection stages were collected, with a particular focus on the plants in the early stages of disease development. Through virulence phenotype analysis, the virulence diversity among the Pst isolates was clarified. Additionally, population genetic diversity was analyzed based on the SSR and SNP molecular markers, exploring the genetic structure of the Pst populations within different regions and the degree of differentiation between populations. The results indicated that the sources of Pst in Qinghai Province during the spring, summer, and autumn are complex and diverse, exhibiting abundant virulence phenotypes and high virulence diversity, with strong pathogenicity. There was significant gene flow among the Pst populations in different counties in Qinghai Province, with the populations in Guide, Datong, Xunhua, and Jianzha displaying unique and diverse pathotypes. The Pst populations in Hualong may contain sexual populations, potentially contributing to the virulence variation of Pst. This study elucidates the genetic characteristics of Pst populations in Qinghai Province, providing theoretical support for the integrated control of wheat stripe rust in the region.

To investigate the species composition and pathogenicity of Fusarium pathogens causing maize ear rot in Shanxi Province, a total of 1 238 diseased ear samples were collected from 51 cities/counties/districts across four geographical regions (Northern, Central, Southern, and Southeastern Shanxi) during 2022-2024. From these samples, 1 430 single-spore isolates were obtained. The pathogens were identified using a combination of morphological and molecular biological methods. The results showed that Fusarium was the dominant genus, comprising 1 229 isolates and accounting for 85.94% of the total isolates. Eleven Fusarium species were identified, including F. verticillioides, F. proliferatum, F. subglutinans, F. graminearum, F. boothii, F. oxysporum, F. incarnatum, F. equiseti, F. poae, F. sporotrichioides, and F. acuminatum, with isolation frequencies of 52.73%, 20.34%, 8.62%, 6.02%, 5.53%, 4.39%, 1.06%, 0.98%, 0.16%, 0.08%, and 0.08%, respectively. The composition and isolation frequency of Fusarium species varied by region and year. F. verticillioides was the most widely distributed species across all regions in Shanxi Province and maintained the highest isolation frequency throughout the study period. Pathogenicity tests demonstrated that F. graminearum was the most virulent, with an average disease rating and disease index of 7.39 and 82.07, respectively. In contrast, F. verticillioides and F. subglutinans exhibited comparatively weaker virulence, with average disease ratings of 2.55 and 1.93, and disease indices of 28.30 and 21.38, respectively. These findings offer a theoretical basis for breeding resistant varieties and developing integrated control strategies for maize ear rot in Shanxi Province.

Cotton Verticillium wilt, caused by Verticillium dahliae, poses a devastating threat on cotton production worldwide. In order to explore new biocontrol resources, this study isolated 213 actinomycete strains from healthy cotton soil. Among these, 22 strains exhibited antagonisticactivity against the highly pathogenic V. dahliae strain Vd592, as determined by dual-culture plate assays and inhibition zone measurements. Three strains with the strongeset antagonistic effect were selected for further study and were identified based on morphological characteristics and 16 S rDNA sequences analysis, and determined for their disease prevention and growth promoting effects on cotton. Results indicate that strain 126 and 2-59 are Streptomyces rectiolaceus, with strain 2-59 showing the highest biocontrol efficacy, achieving a relative prevention effect of 62.72% in pot experiments. Strain 73 was identified as Streptomyces amritsaransis and demonstrated the most significant plant growth-promoting effects, increasing plant height, fresh weight, and dry weight by 8.38%, 16.99%, and 36.82%, respectively. Overall, all three strains exhibited both biocontrol and growth-promoting activities, highlighting their potential to be developed as biocontrol agents against cotton Verticillium wilt.

Ovulinia azaleae Weiss is listed in Chinese quarantine pest and Ovulinia petal blight caused by Ovulinia azaleae brings about significant damage to Rhododendron simsii. A precise enzyme mediated duplex exponential amplification (EmDEA) assay was developed for detection of O. azaleae in this study. Based on ITS gene of O. azalea and related species, the combination of DNA primers and RNA probes was designed and screened in this study. The minimum detection limit was 1.00 pg per 20 μL reaction system. The detection results of suspected sample indicated this method is easy to operate, rapid, and highly specific, which provides an important reference for the detection and screening of O. azaleae in the port.

In some regions of Jilin Province, large scale outbreaks of nematode disease in foxtail millet (Setaria italica) have caused serious damage. Pathogenic nematodes were isolated and identified from 10 samples collected across various regions of Jilin Province. Nine samples yielded pathogenic nematodes who morphological characteristics and measured values for both female and male nematodes were consistent with those described for Aphelenchoides oryzae by Subbotin. The post-vulva to sac of females comprised 23.5% (19.3%-25.5%) of the distance from the vulva to the anus, featuring 4 lateral lines and 3-4 branches at the tail end. Molecular identification, based on comparison of the ribosomal 28S rDNA D2-D3 region and the cytochrome c oxide subunit I (COI) gene in mitochondria, along with phylogenetic tree analysis, revealed that the 9 samples of nematodes clustered with the A. oryzae, for ming a sister clade with A. besseyi. In summary, the nematode isolated from millet ears in Jilin Province was identified as A. oryzae. Clarifying the pathogen of millet nematode and its associated symptoms lays the foundation for effective prevention and control of millet nematode disease.

Turfgrass is an essential component of urban greening, sports, and relaxation, whose health directly affects the aesthetics of cities and the quality of residents’ life. The leaf spot caused by Alternaria leads to the leaf yellowing of turfgrass and thus finally dying away, which threatens its health of turf and reduces the value of ornamental application. In this study, nine isolates of Alternaria were isolated from the diseased leaves of turfgrass, which were collected from turf of urban green space, golf course, and soccer field. Based on morphological characteristics and molecular method, the nine isolates were assigned to two species, namely A. alternata (four strains) and A. tenuissima (five strains). All the nine isolates could infect the leaves of Poa pratensis, causing leaf spot disease, with the average disease incidence and disease index of 100% and 14.32, respectively. This is the first report about Alternaria causing leaf spot disease on turfgrass.

The Orah mandarin, a thick-skinned citrus variety originating from Israel, has been introduced to several citrus-producing regions in southern China in recent years. In March 2022, black rot symptoms were observed on approximately 10% of Orah mandarin fruits in a storage facility in Wuhan City, Hubei Province, China. The fungus was isolated from the diseased tissue and identified based on morphological characteristics and multi-gene sequence analyses, including the large subunit (LSU), the nuclear ribosomal internal transcribed spacer (ITS), beta-tubulin (β-tubulin), and RNA polymerase II (rpb2) genes. The causal organism was identified as Stagonosporopsis pogostemonis, a fungal species not previously reported on Orah mandarin. Pathogenicity tests fulfilled Koch’s postulates, confirming S. pogostemonis as the pathogen responsible for the black rot symptoms. This is the first report of S. pogostemonis causing black rot disease in citrus fruits worldwide.

Tomato canker, caused by Clavibacter michiganensis subsp. michiganensis (CMM), is a severe and difficult-to-manage vascular bacterial disease threatening tomato production. This study aimed to identify highly effective biocontrol agents against CMM, and a bacterial strain ZF516 exhibiting significant antagonistic activity against the pathogen was obtained from tomato rhizosphere. Through morphological observation, physiological and biochemical characterization, and phylogenetic analysis based on multi-gene sequences, ZF516 was identified as Bacillus velezensis. Genomic analysis revealed that the ZF516 genome harbors antibiotic biosynthetic genes encoding lipopeptide antibiotics such as surfactin, macrolactin, fengycin, difficidin, bacillibactin, bacillaene, bacilysin, and iturin. Other biocontrol trait analysis showed that strain ZF516 has the ability to produce protease and siderophore, and solubilize phosphate. Antimicrobial spectrum assays demonstrated that ZF516 effectively inhibited the growth of 6 pathogenic fungi and 6 pathogenic bacteria. Furthermore, pot trials indicated that ZF516 achieved a control efficacy of 78.70% against tomato bacterial canker, higher than that achieved by treatment with thiazole zinc. In summary, strain ZF516 represents the first reported B. velezensis strain exhibiting promising biocontrol efficacy against tomato bacterial canker.

Maize yellow mosaic virus (MAYMV) belongs to Polerovirus, a genus of sense single-stranded RNA viruses. It causes damages to corn and other gramineous crops, resulting in the manifestation of red leaves, dwarfing, deformity and other symptoms in maize plants. Maize is an important food crop in Anhui Province. The occurrence of maize yellow mosaic virus has led to a decline in maize yield. In 2023, a sampling survey was conducted across 16 maize planting areas in Anhui Province. MAYMV incidence in various sampling regions was detected using RT-PCR, and the full-length sequences of the coat protein and movement protein genes (CP and MP, respectively) were amplified. Further analysis was conducted to assess the mutation rates of the CP and MP amino acid sequences from the sampled regions, and a phylogenetic tree for the CP and MP was constructed with MEGA 6. These allowed an analysis of the occurrence and genetic diversity of MAYMV in Anhui Province. The results indicate that MAYMV is generally present and harmful to maize in Anhui Province, with 13 out of 16 sampled regions testing positive for the virus, showing an infection rate ranging from 20% to 100%. Additionally, the CP and MP of MAYMV were relatively conserved across regions, with CP amino acid mutation rates ranging from 0 to 0.01, and MP amino acid mutation rates ranging from 0 to 0.05. Phylogenetic analysis also revealed that MAYMV isolates in the Anhui region are genetically closely related.

Bacteria can regulate their metabolic activities to adapt to external environment via the quorum sensing system, among which ComQXPA is the major one that functions in Bacillus species. Bacillus velezensis strain B31 has shown significant effects in preventing Fusarium wilt diseases on tomato and cucurbit plants. This study aims to explore the impact of the quorum sensing signal molecule ComX on the biocontrol traits of strain B31. By performing deletion mutation of the ComX signal molecule synthesis gene in B. velezensis B31 strain, the ΔcomX mutant was obtained, and its complementary strain CPΔcomX was then constructed. The differences in biocontrol traits were compared among the wild-type B31 strain, the mutant, and the complementary strain. The results indicated that deletion of comX had no significant effect on cell growth, but significantly affected colony morphology, biofilm formation and motility, and significantly reduced extracellular enzyme activities, endospore production rate and inhibitory activity of strain B31 against tomato wilt pathogen. This study clarifies the impact of ComX on biocontrol traits of strain B31, providing a theoretical basis for further utilization of this strain for biological control.

Solanum tuberosum L., one of the four major staple crops in China, is heavily affected by bacterial wilt and tuber rot, a devastating disease caused by Ralstonia solanacearum, which is prevalent in the major potato-producing regions of southwest China. This disease significantly reduces both yield and quality, highlighting the importance of early diagnosis and identification of the pathogen for proactive disease prevention and management. In this study, we developed a rapid and accurate method to detect R. solanacearum in potato seed tubers by integrating specific recombinase polymerase amplification (RPA) with CRISPR-Cas12a technology. Specific RPA primers and CRISPR-Cas12a crRNA were designed based on the fliC gene sequence from GenBank. The isothermal amplification method was optimized, with results visualized using both fluorescence and lateral flow strip assays. Under optimized conditions at a constant temperature of 37 °C, the method demonstrated high specificity, detecting latent R. solanacearum samples from infected seed tubers, without cross-reactivity with other common potato pathogens or soil bacteria. Sensitivity tests showed a detection limit of 10 fg for fluorescence, comparable to qPCR, and 100 fg for lateral flow strips. Field validation of the lateral flow strip method confirmed its practicality for on-site rapid detection, as it is simple to operate and does not require expensive laboratory equipment. On-site testing on different batches of seed potatoes demonstrated the method′s accuracy in detecting latent R. solanacearum infections. In summary, the RPA/CRISPR-Cas12a method developed in this study provides a reliable tool for the early detection of R. solanacearum infections in seed potatoes, facilitating the early prevention and disease diagnosis of potato tubers.

Rapid detection of latent infection by Puccinia striiformis f. sp. tritici (Pst) in wheat leaves is crucial for predicting and controlling wheat stripe rust, thereby safeguarding grain security. In this study, we used conventional PCR with the previously published primer combination betaf/betar to conduct molecular marker detection of Pst in wheat leaves at different inoculation times during the seedling stage. The results demonstrated that Pst amplification products were detectable 26 hours post-inoculation. Additionally, PCR amplification of 268 field-collected wheat leaf samples from six provinces (Shaanxi, Hubei, Anhui, Henan, Shandong, and Shanxi) revealed 45 samples (16.79%) potentially harboring latent Pst infections. Specifically, 29, 10, 3, 2, and 1 positive samples were detected in Henan, Shanxi, Shaanxi, Hubei, and Shandong provinces, respectively, while no latent Pst infections were identified in Anhui.

The fungal genus Verticillium is closely related to vascular bundle diseases in plants, and it includes several important plant pathogenic fungi such as Verticillium dahliae, V. albo-atrum and V. longisporum. Certain Verticillium spp. experienced genomic evolution by inter-specific crosses within the genus leading to an approximate doubling of the genome size and gave rise to allodiploid hybrid V. longisporum, a serious pathogen that severely affects cruciferous plants. Compared with other Verticillium species, V. longisporum exhibits longer conidia, approximately twice the nuclear DNA content, and a higher evolutionary rate. This study reviews the taxonomic status, geographical distribution, host range, morphological characteristics, and symptoms of V. longisporum. It also explores the research progress in detection and prevention of this pathogen. Currently, the prevention and control of this pathogen is difficult, and chemical fungicides cannot provide effective control. Therefore, strict implementation of quarantine measures is the most effective approach to prevent the spread of this pathogen.

Pepper southern blight, caused by Agroathelia rolfsii, which infects the stem, leading to plant wilt, soft rot, and ultimately death, severely impacts pepper yield and quality. The role of effector proteins in the pathogenesis of various pathogenic fungi has been extensively studied; however, the molecular mechanisms underlying the manipulation of host immunity by A. rolfsii effectors are still poorly understood. Based on the whole-genome sequencing data of A. rolfsii, this study screened 618 classical secreted proteins and 84 putative effector proteins using bioinformatics tools including SignalP 6.0, ProtComp 9.0, TMHMM 2.0, and EffectorP 3.0, among which 19 effector proteins contained conserved domains associated with pathogenicity. Through the Agrobacterium-mediated transient plant expression system, it was observed that effector protein EVM0004138 could directly induce necrosis in tobacco cells, while EVM0010618 was capable of inhibiting BAX (BCL2-associated X)-mediated programmed cell death (PCD). RT-qPCR analysis revealed that the genes encoding these two effector proteins were significantly upre-gulated during the infection of pepper by A. rolfsii, with expression levels positively correlated with disease progression. Signal peptide secretion experiments further confirmed their secretory characteristics consistent with those of effector proteins. This study represents the first prediction of the secreted proteins and candidate effector proteins of A.rolfsii, providing a crucial theoretical basis for a deeper understanding of the interaction mechanisms between A. rolfsii and plants.

The monopartite geminiviral V2 protein plays an important role in the viral infection process. Howe-ver, there are few studies on the function of the AV2 protein of bipartite geminiviruses. This study investigated the interaction between the bipartite tomato leaf curl Hsinchu virus (ToLCHsV) AV2 protein and the Nicotiana benthamiana Ran binding protein 1-2b (NbRanBP1-2b), and analyzed their effect on the pathogenicity of the virus. Bimolecular fluorescence complementation (BiFC), GST pull-down and subcellular co-localization were used to validate the interaction between ToLCHsV AV2 and NbRanBP1-2b. NbRanBP1-2b was observed to localize at both the cell membrane and cytoplasm. When ToLCHsV AV2 co-localized with NbRanBP1-2b, the original localization of AV2 and NbRanBP1-2b was altered. After inoculated with ToLCHsV, N. benthamiana leaves exhibited wrinkling, accompanied by delayed growth and development. Furthermore, the relative expression level of NbRanBP1-2b exhibited a gradual increase. When NbRanBP1-2b was silenced by tobacco rattle virus (TRV) or overexpressed by potato virus X (PVX), the virus accumulation in the inoculated N. bentha-miana plants was relatively decreased. These results indicate that ToLCHsV can effectively utilize NbRanBP1-2b to promote virus infection by interacting with its AV2 protein during infection.

The bacterial canker disease of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) has developed into an important limiting factor for kiwifruit production in Anhui province. Samples with typical bacterial canker symptoms were collected in the main kiwifruit orchards from five counties in Anhui province in 2022-2023. A total of 124 Psa isolates were obtained using the dilution plate methods, and subjected to further analysis via repetitive-element PCR genomic fingerprinting (rep-PCR) techniques. The results revealed that three rep-PCR primer pairs amplified 34 clear bands, among which 26 exhibited polymorphism. Based on sampling location, the isolates were divided into five groups, with effective allele numbers, Nei’s gene diversity index, and Shannon index at the species level being 1.19, 0.13, and 0.21, respectively. The highest genetic diversity was observed among the Psa isolates from Jinzhai, while the lowest was found from Huoqiu. UPGMA cluster analysis indicated that the 124 Psa isolates could be classified into three major groups at a genetic similarity coefficient of 0.80, with no significant correlation between group classification and geographical origin of strains. Pathogenicity tests showed that 72 isolates were classified as highly virulent, intermediately virulent,weekly virulent and avirulent strains, accounting for 59.72%, 25%, 5.56%, and 9.72% of the total, respectively. Virulence differentiation was observed among isolates from the same geographical location, host species, or organ, but no significant correlation was found between virulence differentiation and strain origin. Additionally, the insertion of ISPsy36 into the hrpS gene was detected in four avirulent strains, suggesting that the disruption of the type III secretion system (T3SS) function by transposon insertion is one of the primary reasons for the loss of virulence in Psa strains in the field.

Sugar beet is one of the important sugar crops, providing significant value on agricultural production in China. The seedling stage healthiness guarantees the productivity of sugar beets. During May 2020 and 2021, a new leaf spot disease was observed in sugar beet seedlings of paper-pot nursery seedling cultivation area in Ulanqab, Inner Mongolia Autonomous Region. A fungal strain and four bacterial strains were isolated and purified from the symptomatic seedling samples and the pathogenicity were verified by Koch′s postulate. The morphologic characters and phylogenetic reconstruction indicated that the novel seedling disease was caused by the co-infection of Pseudomonas syringae and Fusarium oxysporum. In this study, we identified the causal agents of the seedlings stage disease in Ulanqab, which provides theoretical guidance for prevention and control of seedling diseases and reducing the loss of sugar beet.

During a survey in 2020, cucumber plants in Shandong province displayed yellowing and chlorotic symptoms on leaves. In order to identify the pathogen, eight samples were collected, and PCR was used to test for virus species. The full-length genomic sequences of DNA-A and DNA-B of SLCCNV (squash leaf curl China virus) were cloned, and their phylogenetic relationships were also analyzed. The analysis confirmed the presence of both CCYV(cucurbit chlorotic yellows virus) and SLCCNV in the collected samples. The DNA-A of the SLCCNV genome was 2 735 nt in length, while the DNA-B of SLCCNV was 2 717 nt (GenBank accession no. OM258181 and OM258182). Further results showed that the DNA-A and DNA-B formed an independent cluster and were mostly related to the SLCCNV isolates that reported in China. This is the first systematic report of SLCCNV infecting cucumber in China.

Root rot disease has become increasingly severe on cowpea plants in Hainan Province, China in recent years due to the hot and humid climate conditions. To identify the causal agent of the disease, cowpea plants with typical symptoms of root rot were collected from Sanya City, Hainan Province in June 2023. A total of 20 single-spore fungal isolates with similar morphology were obtained, and their pathogenicity was confirmed by artificial inoculation test. Based on morphological characteristics and phylogenetic relationship inferred from rDNA-ITS, TEF1-α and RPB2 sequences, these isolates were identified as Corynespora cassiicola. This is the first report of cowpea root rot caused by C. cassiicola in China.

Jujube witches′ broom disease, caused by the infection of Candidatus Phytoplasma ziziphi, seriously threatens the healthy development of jujube industry. Disease diagnosis and pathogen detection are important measures for the scientific prevention and control of jujube witches′ broom, and their implementation relies on highly efficient and sensitive molecular detection techniques for Ca. Phytoplasma ziziphi. In this study, based on loop-mediated isothermal amplification (LAMP) technology and different detection methods for its products, three visual detection methods for Ca. Phytoplasma ziziphi were established, namely LAMP-gel electrophoresis, LAMP - HNB/SYBR dye coloration and LAMP-lateral flow dipstick (LFD). Results showed that the established LAMP detection methods had high specificity for Ca. Phytoplasma ziziphi, and the minimum detectable concentration of jujube phytoplasma DNA was 20 pg·μL^-1, which was 100 times more sensitive than conventional PCR. The three detection methods are suitable for the visual detection of Ca. Phytoplasma ziziphi in different application scenarios such as routine laboratories and grassroots plant protection stations. The detection rate of Ca. Phytoplasma ziziphi in the 14 tested jujube tree samples in the field was 100%, which was significantly higher than that of conventional PCR. The LAMP methods developed in this study can rapidly, specifically, and sensitively detect jujube witches′ broom phytoplasma. At the same time, they can eliminate the need for high-cost equipment and are suitable for widespread adoption at the production base level, which are particularly significant for the early diagnosis, monitoring and warning of jujube witches′ broom disease.

In order to rapidly detect tobacco mild green mosaic virus (TMGMV), three sets of RT-LAMP primers based on the conserved sequence of TMGMV coat protein gene were designed to screen and determine the optimal primer combination. The single-variable method was used to optimize the reaction temperature and reaction time. RT-LAMP was then compared with RT-PCR to verify the specificity of the optimized detection, sensitivity and practical application in the field, and the TMGMV RT-LAMP rapid detection technology system was established. The results showed that the optimal reaction condition for RT-LAMP was to amplify at 65 °C for 60 min. The sensitivity of the optimized RT-LAMP was 1 000 times higher than that of RT-PCR, and 1.65×10^-2 copies·μL^-1 template could be detected. There was no cross-reaction with other related viruses during the detection process. The detection results of 60 Rehmannia glutinosa samples showed that the detection rate of the RT-LAMP method (100%) was higher than that of RT-PCR (83.3%). Therefore, the RT-LAMP detection technology established in this study can be used for rapid detection of TMGMV.

In this study, hyphal growth rate and spore production methods were used to determine the indoor inhibitory effect of difenoconazole on Coryneum populinum. Morphotoxicology and transcriptome sequencing were used to analyze the treatment of Differentially expressed genes (DEGs) after treatment with difenoconazole for exploring the antibacterial mechanism of difenoconazole. The results showed that the higher the concentration of difenoconazole treatment, the greater the inhibition effect on C. populinum with lower rates of colony growth and sporulation. After treatment with difenoconazole, 618 DEGs were obtained from C. populinum. GO enrichment analysis showed that DEGs were the most abundant in cell anatomical entities, essential components of membranes, intrinsic components of membranes, and carbohydrate metabolism. KEGG enrichment analysis showed that alanine, aspartic acid and glutamate metabolism, MAPK (mitogen-activated protein kinase) signaling, ribosomal biosynthesis and metabolism were all in the first 20 enrichment pathways. Twenty-six key genes were up-regulated and nine key genes were down-regulated in MAPK signaling, including Ste2, Cdc42, Ste18 and Mcm1 in the Fus3/Kss1 signaling pathway (P<0.05), Cdc42 in the HOG signaling pathway (P<0.05), and CWI signaling pathways Wsc1, Slt2 and Fks2 in the up-regulated manners (P<0.05). The results provided data support for revealing the response mechanism of C. populinum to difenoconazole stress and research basis for the further development of synergistic agents of triazole fungicides.

Pokkah boeng disease (PBD) is one of the most important fungal diseases threatening sugarcane production, and the major pathogen causing the disease is Fusarium sacchari in China. The survival factor Svf1 was first reported in Saccharomyces cerevisiae, which plays an important role in fungal growth, development and pathogenicity to plants. In this study, we found a Svf1 homologous gene FsSvf1 in the genome of F. sacchari, and the amino acid sequence similarity between the two proteins was 46.4%. The expression level of FsSvf1 was significantly up-regulated in sugarcane plant at 72 h post-inoculation with F. sacchari. Compared with the wild-type strain of F. sacchari, the FsSvf1 deletion mutant showed a significantly reduced mycelial growth rate, an obviously changed colony morphology on artificial media, and an increased sporulation ability; however, the number of perithecia produced by the FsSvf1 deletion mutant was reduced and the maturation time of ascus was delayed on carrot medium; under NaCl stress, the FsSvf1 deletion mutant showed increased sensitivity to NaCl, but under Congo red-, SDS- and H₂O₂-stressed conditions, the FsSvf1 deletion mutant exhibited reduced sensitivity to these stress agents; the pathogenicity of the FsSvf1 deletion mutant to sugarcane was also significantly reduced. These results demonstrate that FsSvf1 is a factor that plays important roles in the growth, development and pathogenicity of F. sacchari to plants, with the potential to be used as a target for disease control.

Magnaporthe oryzae populations in rice fields exhibit a complex genetic structure, particularly with rapid variation in avirulence genes, which is the primary reason for the decline in disease resistance of resistant rice varieties after several years of cultivation. Therefore, Monitoring of genetic variation in avriulence genes of M. oryzae is of great significance for the rational deployment of resistant rice varieties. In this study, polymerase chain reaction (PCR) and Sanger sequencing were used to analyze the distribution and variation of the avirulence gene AVR-Pita in 84 M. oryzae isolates from different rice-planting areas in Guangxi Zhuang Autonomous Region. The results showed that 66 out of the 84 isolates contain the AVR-Pita gene. Sequence alignment results demonstrated that these 66 M. oryzae isolates contain 6 AVR-Pita variation types (AVR-Pita H1-H6). Inoculation of rice seedlings and detached rice leaves with M. oryzae isolates containing different AVR-Pita variation types revealed that M. oryzae of all these variation types could infect Lijiangxintuanheigu (Pi-ta-LTH) carrying the Pi-ta gene, indicating that the 6 variation types could not be recognized by the resistant Pi-ta gene. This study revealed the variation of the AVR-Pita gene in M. oryzae in Guangxi Zhuang Autonomous Region, suggesting the significance of regular monitoring of the variation in this avirulence gene. These findings not only provide a scientific basis for the rational deployment of rice varieties containing the resistance gene Pi-ta in Guangxi Zhuang Autonomous Region but also lay an important foundation for formulating effective control strategies for rice blast disease.

Peach brown rot disease caused by Monilinia fructicola has resulted in huge economic losses to peach production in China, and identification of the key pathogenic factors of M. fructicola is crucial for targeted prevention and control of the disease it caused. To investigate the biological functions of MfHOX1 in M. fructicola, the Split-Marker method and PEG-mediated homologous recombination transformation were used here to obtain the MfHOX1 knockout mutant and its complementary strain. Compared with the wild-type strain of M. fructicola, the mycelial growth rate of the MfHOX1 knockout mutant was significantly decreased, while the conidial production was increased; the sensitivities of MfHOX1 knockout mutant to exogenous stresses including H₂O₂, SDS, CR, CaCl₂ and NaCl were significantly decreased, but those to glycerol, sorbitol and glucose were increased. In addition, the virulence of the MfHOX1 knockout mutant was significantly reduced, and the expression levels of several pathogenicity-related genes such as MfAP1, MfPG1, MfCUT1, MfPmk1, MfSSP and MfHsbA1 were significantly increased due to the deletion of the MfHOX1 gene. The aforementioned results suggest that MfHOX1 plays roles in regulating mycelial growth, sporulation, pathogenesis and external stress responses.

Nucleus-localized effector proteins secreted by plant pathogenic fungi can enter plant cell nucleus and interfere with host’s nuclear biological functions. It is of great significance to elucidate the underlying molecular mechanism of nucleus-localized effector proteins in regulating host immune response during Gymnosporangium yamadae-Malus domestica interaction. In this study, the subcellular localization of the two candidate nucleus-localized effector proteins from G. yamadae, GyBarwin55 and GyRlpA22 obtained in our previous study, was determined via Agrobacterium tumefaciens-mediated transient expression in Nicotiana benthamiana, and the result showed that GyBarwin55 was specifically localized to the nucleus, and GyRlpA22 was localized to both cytoplasm and nucleus. Quantitative real-time PCR (qPCR) analysis result showed that the expression level of these two effector protein-coding genes in apple seedlings was significantly up-regulated during the spermatial development stage of G. yamadae. The results of heterologous expression in Nicotiana benthamiana mediated by A. tumefaciens, combined with that of in situ expression in apple leaves, demonstrated that both GyBarwin55 and GyRlpA22 have elicitor activities. However, site-directed mutagenesis of the nuclear localization sequence (NLS) resulted in the loss of the ability of GyBarwin55 and GyRlpA22 to localize to the nucleus and also to act as elicitors. The above results revealed that the NLS sequence is indispensable for both GyBarwin55 and GyRlpA22 to localize to nucleus and function as elicitors, and these two nucleus-localized effector proteins play important roles during the interaction between G. yamadae and apple tree.

Verticillium dahliae is the causal agent of potato Verticillium wilt disease, a disease that significantly reduces potato yield and quality. To explore novel biocontrol resources against this disease, a bacterial strain designated Z-7, which exhibited strong antagonistic activity against V. dahlia, was isolated and screened from maize rhizosphere soil. Based on morphological characteristics and phylogenetic analysis, strain Z-7 was identified as Bacillus amyloliquefaciens. Further investigations revealed that volatile organic compounds (VOCs) produced by this strain strongly inhibited V. dalhliae: they significantly reduced mycelial biomass, induced abnormal hyphal morphology (including swelling, surface roughness, and collapse), and markedly decreased conidial germination rate. Additionally, the VOCs inhibited microsclerotia formation and melanin synthesis, and significantly down-regulated the expression of genes related to these processes. Analysis of the VOCs composition via gas chromatography-mass spectrometry (GC-MS) identified 11 compounds, with amines and 2,5-dimethylpyrazine (2,5-DMP) being the most abundant. Indoor toxicity assays showed that 2,5-DMP caused hyphal malformation and fragmentation in V. dahliae. Pot inoculation experiments demonstrated that this compound effectively reduced the disease index of potato Verticillium wilt without adversely affecting potato growth. In conclusion, strain Z-7 and its volatile metabolite 2,5-DMP exhibit strong biocontrol potential against potato Verticillium wilt. This study provides new microbial resources and a theoretical basis for the biocontrol of this disease.

A leaf blight disease seriously affecting the quality and yield of Alpinia katsumadai Hayata was discovered at the Academy of Tropical Agricultural Sciences Nursery Agriculture Base, Chinese Academy of Tropical Agricultural Sciences, Danzhou City, Hainan Province. The pathogen AH-1, which caused the disease, was isolated from the disease lesion of Alpinia katsumadai Hayata. Based on both morphological characteristics and phylogenetic analysis of multiple gene sequences, including β - tubulin (TUB2), internal transcriptional spacer (ITS), and ribosomal subunit (LSU), this pathogen was further identified as the species Neoscirrhia mateuciicola. The study of this pathogen provides a basis for the prevention and control of Alpinia katsumadai Hayata leaf blight.

Rubber tree powdery mildew pathogen Oidium heveae, complete its infection cycle on living host plant through secreting a plethora of effectors proteins. The expression of candidate effector gene CSEP03399, encoding an N terminal secretion signal peptide, was induced during O. heveae infection on Arabidopsis. No obvious cell deaths were observed after CSEP03399 expression in transgenic Arabidopsis plants and Nicotiana benthamiana, suggesting that CSEP03399 is not an avirulence effector protein. After inoculated with O. heveae, CSEP03399 can obviously enhance the fungal growth in early stage and the conidospores formation in late stage, The ROS production, cell death and the expression of PR1(pathogenesis related 1)gene were significantly reduced. All this indicated that CSEP03399 was a virulence effector protein for plant cell. However, the hypersensitive responses triggered by powdery mildew resistance gene WRR4B (white rust resistance 4B), Pseudomonas syringae DC 3000 avrB and DC 3000 avrRpt2 were not inhibited by CSEP03399. Nonetheless, the expressions of chitin-induced FRK1 (FLG22-induced receptor-like kinase 1) and WRKY22 gene were suppressed by CSEP03399 and the pathogenicity of P. syringae DC 3000 and DC 3000 hrcC^- was enhanced after Arabidopsis treated with chitin. Overall, these results suggested that CSEP03399 may fulfill its virulence by inhibiting the chitin-triggered immune signaling.

Yam cultivation is frequently affected by various viral infections, which reduce yield and quality. In order to achieve efficient and rapid detection of yam viruses, a multiplex PCR assay was developed that could simultaneously detect youcai mosaic virus (YoMV), Japanese yam mosaic virus (JYMV), broad bean wilt virus-2 (BBWV-2), and yam latent virus (YLV) and yam yellow spot mosaic virus (YYSMV). The amplification target sizes of these viruses were determined to be 504, 614, 750, 1 030, and 1 207 bp, respectively. The optimal annealing was achieved at 55°C, with virus-specific primer concentrations of 0.08 μmol·L^-1, 0.04 μmol·L^-1, 0.16 μmol·L^-1, 0.32 μmol·L^-1, 0.24 μmol·L^-1 for YoMV, JYMV, BBWV-2, YLV, YYSMV, respectively. The detection sensitivity reached 8.11×10⁵ copies·μL^-1. The assay was demonstrated to reliably and effectively detect all five viruses in yam samples, greatly improving the detection efficiency in the practice applications. This technique is of great value for ensuring the quality of detoxified yam propagation material.

To investigate the prevalence of lily mottle virus (LMoV) in lilies from Nanping City, Fujian Province, RT-PCR assay was employed to detect 48 infected leaf samples. From a subset of LMoV-positive samples, coat protein (cp) gene was amplified, cloned and sequenced. The obtained sequences were comparatively analyzed with all available published LMoV cp sequences to assess sequence variation and phylogenetic relationships. RT-PCR results showed that 32 out of 48 (66.7%) lily samples tested positive for LMoV, indicating widespread prevalence of the virus in Nanping City, Fujian Province. Using a specific primer pair LMoV-F/LMoV-R, the expected fragments were successfully amplified from 14 randomly selected positive samples. These sequences showed 86.34% to 99.88% nucleotide identity with the previously reported LMoV isolates. Phylogene-tic analysis classified all LoMV isolates into three distinct groups (Group I, Group II and Group III), with our 14 isolates forming a well-supported cluster within Group I. Phylogeny-trait association analysis revealed that isolates from the same region tend to cluster together, suggesting a possible correlation between LMoV diversification and geographic origin. Bayesian skyline plot (BSP) analysis showed that China LMoV population remained stable before 2010, but subsequently underwent dramatic expansion, followed by a recent slight decline which warrants continued monitoring due to its potential impacts on lily production. This study provides important insights into LMoV prevalence, molecular characteristics and population dynamics in Nanping City, Fujian Province, establishing a foundation for epidemiological monitoring and control strategies.

Tomato leaf curl New Delhi virus (ToLCNDV) and tomato yellow leaf curl virus (TYLCV) are both transmitted by whiteflies. Under natural conditions, the disease caused by coinfection with ToLCNDV and TYLCV is destructive to tomato plants. Therefore, it is crucial to establish an accurate, rapid, and simultaneous detection method for these two viruses to facilitate rapid diagnosis and field monitoring. A dual recombinase polymerase amplification (RPA) assay targeting ToLCNDV and TYLCV was developed on the basis of RPA technology. This assay offers a sensitivity of 10⁴ copies·mL^-1 and takes a reaction time of only 25 minutes. It can be used for detecting ToLCNDV and TYLCV in both plants and whiteflies, providing a convenient, sensitive and effective method for the identification and monitoring of these two viruses.

Fagus longipetiolata Seem. is one of the main tree species for afforestation in high-altitude regions of China, possessing significant economic and ecological value. In May 2023, a leaf spot disease was observed at the F. longipetiolata-planting areas in Huangping County, Guizhou Province. The disease was manifested as brown spots with dark brown margins on leaves. To identify the causative agent of the disease, we performed tissue isolation to get potential pathogens and further confirmed their pathogenicity following Koch′s postulates. The isolates were identified as Alternaria alternata based on morphological characteristics and phylogenetic relationship inferred from rDNA-ITS, TEF-1α, and GAPDH sequences. This is the first report of A. alternata causing leaf spot on F. longipetiolata in China. The results provide a basis for the development of effective prevention and control strategies for this disease.

For rapid and accurate detection of Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), we developed a novel TaqMan quantitative real-time PCR assay. The specific probe Cff-P was designed based on Cff genomic sequence in GenBank, and quantitative real-time PCR(qPCR) detection method was constructed for the first time. Validation experiments demonstrated that the assay could specifically detect 34 strains of Cff without cross-reactivity, 66 strains non-target, or blank control The detection sensitivity was determined to be 50 fg·μL^-1 bacterial DNA through serial dilution experiments. Field application of this method to 140 bean seed samples confirmed its reliability and practicality for Cff detection in seed materials. The established TaqMan quantitative real-time PCR detection method provides a technical platform for the rapid Cff screening of agricultural departments and entry ports in China.

Tobacco black shank caused by Phytophthora nicotianae is a major soil-borne disease in tobacco-producing areas, which usually co-occurred with Fusarium root rot in the same tobacco plant in recent years. When this happens, it is difficult to isolate P. nicotianae from Fusarium spp. that cause tobacco root rot. To selectively isolate P. nicotianae from diseased tobacco plants co-infected with P. nicotianae and Fusarium spp., novel selective media were developed in this study. Oat agar medium containing appropriate concentrations of fludioxonil, hymexazol, difenoconazole, fluazinam, imazalil or tebuconazole were used to test inhibitory effect of these fungicides on mycelial growth of Fusarium solani, Fusarium oxysporum and P. nicotianae, and the results showed that both 50 μg·mL^-1 imazalil and 20 μg·mL^-1 tebuconazole could effectively inhibit mycelial growth of F. solani and F. oxysporum rather than that of P. nicotiana. The oat agar media containing either 50 μg·mL^-1 imazalil or 20 μg·mL^-1 tebuconazole were then used to isolate pathogens from naturally diseased tobacco plants with typical symptoms of both black shank and root rot, as a result, the isolation rate of P. nicotianae was 80%-90%, significantly higher than that (35%) obtained with oat agar medium. Therefore, the selective media containing either 50 μg·mL^-1 imazalil or 20 μg·mL^-1 tebuconazole, which we developed in this study, are suitable for high-throughput isolation of the black shank pathogen P. nicotianae from tobacco plants with complex infection by P. nicotianae and Fusarium spp.

The sensitivity and cross-correlation of 33 fungal isolates causing pepper anthracnose to 7 fungicides (azoxystrobin, triadimenol, propiconazole, prochloraz, iprodione, thiophanate-methyl and cyclobutrifluram) were investigated in this study. The results showed that the average EC₅₀ values of the 6 fungicides (azoxystrobin, triadimenol, propiconazole, prochloraz, iprodione and thiophanate-methyl) to these isolates were (147.254±76.028), (15.900±24.1368), (1.281±1.664), (0.217±0.266), (3.183±2.253) and (61.240±51.893) μg·mL^-1, respectively; cyclobutrifluram had no inhibitory activity against the tested pepper anthracnose pathogens. Among the 6 fungicides with inhibitory effect, the sensitivity distribution of these isolates to azoxystrobin followed a normal distribution, while that to the other 5 fungicides did not follow a normal distribution, which indicated that pepper anthracnose pathogen populations with decreased sensitivity to these 5 fungicides had emerged. Spearman′s rank correlation analysis result indicated that there was a significant positive correlation between the sensitivity of pepper anthracnose pathogens to 3 sterol demethylation inhibitors (DMIs), i.e. triadimenol, propiconazole and prochloraz; there was a significant positive correlation between the sensitivity to thiophanate-methyl and that to these 3 DMIs; there was a significant negative correlation between the sensitivity to iprodione and that to the 3 DMIs and thiophanate-methyl; there was no correlation between the sensitivity to azoxystrobin and that to the other tested fungicides. Colletotrichum scovillei isolates showing different sensitivity to thiophanate-methyl, a methyl benzimidazole carbamate (MBC) fungicide, were selected, and the targeted β-tubulin gene was amplified and analyzed from these C. scovillei isolates. It was found that no site mutations occurred in β-tubulin gene in C. scovillei isolates with lower sensitivity to thiophanate-methyl, however, the expression level of β-tubulin gene in lowly-sensitive isolates was higher than that in highly-sensitive isolates under treatment with thiophanate-methyl. The results provide guidance for the scientific selection and rational alternation of fungicides in controlling pepper anthracnose disease, and also lay a basis for molecular detection of MBCs-resistant anthracnose pathogens.

Phytophthora sojae causes root rot primarily through its zoospores, which sense soybean root-secreted isoflavones (genistein and daidzein) to locate and infect the host. Previous studies have identified the genistein receptor PsIRK1 and the daidzein receptor PsIRK3 in this pathogen and further identified esculetin as a specific antagonist that disrupts the PsIRK1-mediated chemotactic response. However, compounds capable of simultaneously interfering with chemotaxis induced by both isoflavones have remained unexplored. This study aimed to screen natural small-molecule compounds that inhibit the chemotactic effects of both genistein and daidzein. Chemotaxis interference assays showed that 6-hydroxycoumarin, at a concentration of 100 μmol·L^-1, significantly disrupted zoospore chemotaxis toward both isoflavones. Mechanistic studies revealed that this interference depends on the PsIRK3-dependent pathway but does not involve direct receptor binding. Quantitative real-time PCR (qPCR) analysis indicated that 6-hydroxycoumarin treatment significantly downregulated PsIRK1 and PsIRK3 expression to 43% and 58% of control levels, respectively. Furthermore, the compound inhibited mycelial growth of P. sojae. Pot experiment results demonstrated that treatment with 100 μmol·L^-1 6-hydroxycoumarin significantly enhanced the survival rate of soybean seedlings under P. sojae infection to 50%. This study identifies 6-hydroxycoumarin as a novel chemotaxis-interfering agent that mitigates P. sojae-induced root rot by suppressing chemoreceptor gene expression and hindering mycelial growth, providing a new strategy for ecologically sustainable disease control based on disrupting pathogen perception.

Viral diseases pose a dramatic threat to the yield and quality of vegetables; therefore, the establishment of rapid and accurate detection techniques for multiple vegetable virus diseases is of great practical value. This study focuses on four viruses that are particularly pathogenic and commonly infect vegetables in the field, namely cucumber mosaic virus (CMV), turnip mosaic virus (TuMV), broad bean wilt virus-2 (BBWV-2) and zucchini yellow mosaic virus (ZYMV). A multiplex RT-PCR detection method capable of simultaneously identifying these four viruses was established by optimizing reaction conditions, primer design, optimal primer concentrations and annealing temperatures. The developed method was shown to be specific and sensitive. The optimal primer ratios were found to be 5∶15∶4∶3 for ZYMV∶TuMV∶BBWV-2∶CMV with an annealing temperature of 55 ℃. The sensitivity of this reaction system was determined to have a minimum template requirement of 0.2 μg. This method was applied to detect these four viruses in 8 vegetable samples collected from the Qingdao City region, and the results were consistent with those of the single RT-PCR detection. This multiplex RT-PCR detection method was shown to be stable, accurate and highly sensitive, offering a feasible solution for the rapid and effective detection of viral diseases in the field.

Citrus canker, caused by Xanthomonas citri subsp. citri (Xcci), is a devastating bacterial disease in citrus production. Current control strategies primarily rely on copper-based compounds and antibiotics, yet their overuse poses increasing environmental and health risks. In recent years, phage-based biocontrol strategies have gained widespread attention due to their high specificity and environmental friendliness. In this study, a lytic bacteriophage named SAC was isolated from soil samples using the double-layer plate method with Xcci strain N8 as the host. The whole-genome sequencing results revealed that the SAC genome encodes 55 genes. Sequence alignment indicated that this bacteriophage belongs to the class Caudoviricetes. Transmission electron microscopy revealed that SAC has an icosahedral head approximately 60 nm in diameter, and belongs to the family Podoviridae within the order Caudovirales. Biological characterization showed that SAC lysed all 14 tested Xcci strains from diverse origins, yielding a lytic rate of 100%; the optimal multiplicity of infection (MOI) was determined to be 0.001, resulting in a phage titer of 4.5 ×10¹¹ PFU·mL^-1; SAC remained stable within a temperature range of 4-60 ℃ and a pH range of 4-11, but exhibited sensitivity to ultraviolet radiation; one-step growth curve analysis indicated a latent period of 60 min, a burst period spanning 60 to 160 min, and a burst size of 430 PFU·cell^-1. In liquid culture, the addition of SAC significantly suppressed the growth of Xcci N8, as the bacterial concentration initially increased briefly and then continued to decrease, remaining at a low level. In planta experiments demonstrated that spraying SAC effectively inhibited the growth and spread of Xcci N8 in citrus plants. These results indicate that phage SAC exhibits strong inhibitory effects against Xcci and Xcci-induced citrus canker and has great potential to be developed as a novel biocontrol agent.

Primers and probes were designed for detection of the coat protein gene of tobacco mild green mosaic virus (TMGMV). A rapid detection method for TMGMV was established by combining recombinase polymerase amplification (RPA) and lateral flow dipstick (LFD). The reaction time and reaction temperature in the detection method were optimized, and the specificity and sensitivity of the method were tested. The results showed that the optimum reaction conditions for the RT-RPA-LFD detection system were a temperature 37 °C and a reaction time of 30 min. The method can specifically detect TMGMV and has no cross-reaction with other viruses. The minimum detection limit for TMGMV is 1.65×10⁰ copies·μL^-1, which is 10 times higher than that of ordinary PCR detection. The method has high sensitivity and specificity, and can be used for the detection of TMGMV in Rehmannia glutinosa samples. It is convenient for grassroots scientific research units to accurately detect and diagnose the virus.

Gastrodia elata is a precious Chinese medicinal herb, and Zhaotong is a genuine producing area for G. elata. However, tuber rot disease severely restricts the sustainable development of this industry. In this study, pathogenic fungi were isolated and purified from diseased G. elata samples collected in Zhaotong City, Yunnan Province. Through morphological and molecular identification, combined with pathogenicity tests, the pathogen causing G. elata tuber rot disease was identified as Mariannaea lignicola. Analysis of the biological characteristics revealed that the optimal conditions for mycelial growth of M. lignicola were oatmeal agar (OA) medium, pH 7.0, 32 °C, and complete darkness, while the optimal conditions for conidial production were potato dextrose agar (PDA) medium, pH 6.0, 28 °C, and full light. Using Czapek-Dox medium as the basal medium, the effects of different carbon and nitrogen sources on the growth and sporulation of M. lignicola were investigated. It was found that soluble starch as the carbon source and nitrogen deficiency promoted the fastest mycelial growth, while soluble starch as the carbon source and yeast extract as the nitrogen source were more conducive to sporulation. The pathogen can produce cell wall-degrading enzymes (CWDEs) including carboxymethyl cellulase (CMCase), polygalacturonase (PG), and polymethylgalacturonase (PMG). The activity of these enzymes was significantly higher in diseased tissues than in healthy tissues, indicating that CWDEs play a key role in enabling M. lignicola to infect Gastrodia elata and cause tuber rot disease. This study is the first to report M. lignicola as the pathogen of G. elata tuber rot disease in China, providing a theoretical foundation for the integrated control of this disease.

Fusarium graminearum is the primary pathogen causing wheat scab. The heat shock protein Hsp30, an ATP-independent molecular chaperone, binds to partially denatured proteins, facilitating their correct refolding and preventing irreversible damage. In this study, we used homologous recombination to generate the knockout mutant of FgHSP30 (ΔFgHsp30) and its complemented transformant ΔFgHsp30-C. Our results indicated that compared to the wild-type strain PH-1, the growth rate and colony morphology of the ΔFgHsp30 mutant exhibited no significant changes. However, its conidial yield decreased by approximately 49%, accompanied by alterations in the number of conidial septa. RT-qPCR analysis revealed that the FgHSP30 gene was up-regulated in the early stage of wheat infection by F. graminearum. The pathogenicity test demonstrated that the pathogeni-city of the ΔFgHsp30 mutant was significantly reduced in wheat compared to the wild type. Furthermore, toxin detection showed that the biosynthesis of DON toxin in the ΔFgHsp30 mutant was inhibited, with a notable reduction in the transcription levels of TRIs genes. Additionally, RT-qPCR results showed that the FgHSP30 gene was highly expressed under elevated temperature conditions, while the ΔFgHsp30 mutant exhibited severe impairment in heat shock resistance. In summary, the heat shock protein FgHsp30 plays a crucial role in the asexual reproduction, high-temperature stress response, pathogenicity, and toxin production of F. graminearum.