To clarify the pathogen species and isolation frequency inside and outside of soybean seeds in Inner Mongolia, and to make clear whether soybean seeds carry quarantine pathogen Phytophthora sojae, a total of 218 isolates were obtained from the inside of seeds and 196 isolates were obtained from the outside of seeds using washing assay and medial culture method, respectively. P. sojae was not isolated from the soybean seeds tested. Combined with colony morphology observation and ITS-rDNA sequence analysis, the above isolates were preliminarily identified. The internal isolates of seeds belonged to 16 genera, and the external isolates of seeds belonged to 17 genera. In combination with literature reports, 24 candidate fungal strains belonging to 9 genera were selected and tested for virulence, it showed that they all could cause lesions on etiolated soybean seedlings. Finally, the tested soybean seeds were confirmed to be free of P. sojae by specific primer amplification. These results provide an important reference for the scientific control of soybean diseases caused by seed borne pathogens.

To identify the pathogens causing root rot on Lonicera japonica, we collected diseased root samples and conducted microbe isolation. The causal agents of the disease were identified as Fusarium solani and Fusarium incarnatum through pathogenicity test, and based on morphological characteristics and phylogenetic analysis results, and combined infection by these two species of fungi led to more severe symptoms. The optimal tempera-ture for mycelial growth of the two pathogens is 28 ℃, and the growth was suppressed when the temperature was lower than 4 ℃ and above 50 ℃; The optimal temperature for spore germination of F. incarnatum is 28 ℃, and 25-28℃ for F. solani; The two pathogens are insensitive to pH and can grow at pH 5-11; A light/dark cycle of 12 h light/12 h dark is suitable for mycelial growth of F. incarnatum, while total darkness is suitable for F. solani; The lethal temperatures for mycelial growth of F. incarnatum and F. solani are 50 ℃ and 55 ℃ for 10 min respectively, and are 50 ℃ for 10 min for spore germination of both the pathogens; The most suitable carbon source for both fungal pathogens is pectin, and the most suitable nitrogen source is tryptone for F. incarnatum but peptone for F. solani. In addition, the utilization efficiency of F. incarnatum is low to the other tested nitrogen sources, whereas F. solani showed a broad-spectrum adaptability to carbon and nitrogen sources. To explore biocontrol agents against F. incarnatum and F. solani, bacterial strains were isolated from rhizosphere soil of healthy L. japonica. By confronting incubation test, enzyme activity test and pot experiment in greenhouse, two strains BG1 and BS37, which showed good performance in promoting the growth of L. japonica and controlling root rot, were obtained. BG1 and BS37 were identified as Paenibacillus polymyxa and Bacillus subtilis, with a control efficacy of 59.41% and 52.47%, respectively. The results provide good potential biocontrol resources for the control of L. japonica root rot.

In order to clarify the the population structure types, pathogenicity and the potential risks to different crops of Verticillium wilt of watermelon, the physiological type, physiological races, mating types and pathogenicity differentiation of Verticillium dahliae from watermelon were measured and the pathogenicity of 20 strains was studied by using root-drenching method. At the same time, the pathogenicity to watermelon of V. dahliae from six crops and the pathogenicity to four crops of V. dahliae from watermelon were determined. The results showed that all the 20 strains were identified as nondefoliated stains, physiological race 2 and MAT1-2-1 mating type. There were significant differences in the pathogenicity among the tested strains, the AUDPC values were from 238.92 to 606.81, the AUDPC values of WM05 and WM14 strains were 606.81 and 514.72, respectively, which were significantly higher than those of the other 18 strains. The pathogenicity of WM05 and WM14 strains was relatively strong. However, the AUDPC values of WM01, WM20, WM24 and WM19 strains were only 238.92, 249.15, 256.11 and 257.45, which showed relatively weak pathogenicity. V. dahliae from cotton, eggplant, potato, sunflower, tomato and honeysuckle could infect watermelon, and there were significant differences in pathogenicity. V. dahliae from watermelon could infect cotton, eggplant, potato and sunflower. The pathogenicity was the strongest on eggplant and was the weakest on cotton, and was comparable to that of watermelon on potato and sunflower.

Potato common scab is caused by Streptomyces spp. Potato common scab disease is widely distributed in potato producing areas of the world. For many years, common scab has hampered the potato industry, especially the developing of seed potatoes industry. In this paper, the occurrence of common scab, pathogen distribution, disease detection, pathogenic mechanism, cultivar resistance research and green prevention and control technology were reviewed, and the urgent problems in potato common scab research were put forward in order to provide new ideas for in-depth research and green prevention and control of potato common scab.

Strawberry angular leaf spot is one of the important bacterial diseases in Yunnan in recent years. In this study, a bacterial strain isolated from the strawberry leaf lesion was identified as Xanthomonas fragariae based on morphological, physiological and biochemical analysis, pathogenicity detection, as well as the phylogenetic analysis of the 16S rDNA and hrpB genes. The physiological and biochemical detection showed that the pathogenic bacterium could utilize 26 carbon sources such as D-maltose, D-trehalose, D-cellobiose, sucrose and D-pintobiose. It can react with seven chemical sensitive substances such as nalidixic acid and lincomycin. The pathogenic bacterium had weak salt tolerance, sensitive to acid, and could use organic acids such as L-lactic acid and citric acid. The disease resistance evaluation experiment showed that ‘Benihoppeand’ and ‘Sweet Charlie’ were highly resistant varieties, with disease indexes of 5.95 and 4.76, respectively, and the proportion of highly resistant varieties was 14.28%. The moderately resistant varieties included ‘Portola’, ‘All star’, ‘Yuexiu’, ‘Snow White’, ‘Jingzangxiang’, and ‘Xiangye’, and the proportion of moderately resistant varieties was 42.85%. In conclusion, we identified the pathogenic bacterium of strawberry angular leaf spot, and obtained several disease-resistant strawberry varieties through screening. These results laid a foundation for further research on the characteristics of disease occurrence and prevention methods.

In this study, the mating types, physiological race composition, and genetic structures of 66 Phytophthora capsici isolates, collected from Chongqing during 2019-2020, were revealed by antagonistic culture, root-irrigation inoculation of differential hosts, and simple sequence repeats (SSR) marker-based analysis. The results showed that there were 53 P. capsici isolates of A2 mating type and 13 isolates of A1 mating type; 11 isolates of race 1, 28 isolates of race 2, 1 isolate of race 3, and 2 isolates of race 6. Genetic variation analysis of the P. capsici population, which consists of 11 different geographical sub-populations, was carried out by using six common SSR markers, and 59 different genotypes were obtained in total, with effective alleles of 1.786-2.881, expected heterozygosity of 0.352-0.577, Shannon-Wiener index of 1.242-2.079, and percentage for polymorphic markers of 83.33%-100%, and high levels of gene exchange occurring within subgroups (Nm=0.133-7.680) were indicated by medium population differentiation (F_ST=0.113). It was concluded that the degree of genetic variation of P. capsici populations in different regions of Chongqing was different, while the whole population had a surplus of heterozygotes, indicating a rich genetic diversity. The mating type proportion, fixation index, Hardy-Weinberg balance and linkage disequilibrium analysis for each geographical population showed that asexual and sexual reproduction may co-exist in P. capsici populations of Chongqing. Analysis of molecular variance (AMOVA) further showed that genetic variation mainly occurred within populations. Discriminant analysis of principal components (DAPC) showed that there were obvious differences and group division among P. capsici isolates from Chongqing, which could be divided into two groups. Structural analysis showed that P. capsici in Chongqing may come from two different ancestral groups. The results lay a basis for the control of Phytophthora blight of pepper plants.

Rice bacterial leaf streak, the main bacterial disease caused by Xanthomonas oryzae pv. oryzicola (Xoc), seriously affects rice production. Exploring safe and efficient biological resources is very important for the control of the disease. In this study, an endophytic bacterial strain XP-1 was obtained from rice leaves by confronting incubation method, with an inhibition zone diameter of (56.1±0.1) mm against Xoc. XP-1 also exhibited good antagonistic activity against 5 common bacterial phytopathogens (Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, Ralstonia solanacearum, Pectobacterium carotovorum subsp. carotovorum, Xanthomonas fragariae and Xanthomonas campestris pv. campestris). Physiological and biochemical test showed that XP-1 strain can produce IAA and siderophore, and solubilize phosphate but cannot solubilize potassium and fix nitrogen. Through indoor seed soaking test and greenhouse pot experiment, it was showed that the diluted fermentation broth of XP-1 could promote seed germination and seedling growth of rice plants, and inhibit leaf lesion on 3 rice varieties, with an inhibition rate of 63.72%-94.47%. The beneficial endophytic XP-1 strain, which has a wide antimicrobial spectrum, was identified as Pantoea ananatis based on morphological characteristics, physiological and biochemical properties and molecular identification results. This study provides the foundation for further exploration of biological resources for rice bacterial leaf streak control.

Viruses in the genus Polerovirus of the family Solemoviridae exhibit a broad host range and can infect plants from many families, including Fabaceae, Solanaceae, Cucurbitaceae, Brassicaceae and others. They are responsible for significant economic losses globally and frequently co-infect with umbraviruses, which are members of the family Tombusviridae, leading to severe plant diseases. In order to explore the occurrence and distribution of poleroviruses in Yunnan, along with the potential outbreak risk associated with co-infection involving umbraviruses, a comprehensive disease survey was conducted in commercial crops including vegetables and fruits, as well as in the weeds surrounding these crops in Yunnan. Additionally, virus species were also detected and identified by RT-PCR. A total of 669 samples of 5 families, comprising 25 species of commercial crops and surrounding weeds, including vegetables, tobacco, potatoes, passion fruit and others, were collected from 7 states and cities in Yunnan Province, including Kunming, Yuxi, Baoshan, Dali, Chuxiong, Xishuangbanna and Honghe. Among the 11 commercial crops, 6 species of poleroviruses were found, which were the species potato leafroll virus, the species cucurbit aphid-borne yellows virus, the species suakwa aphid-borne yellows virus, the species pepper vein yellows virus 1, the species pepper vein yellows virus 3, and the species brassica yellows virus, respectively. Among them, PeVYV-3 had the highest average detection rate of 6.73% and was the dominant virus species in vegetables and fruits in Yunnan province. It was the first report in domestic and abroad that BrYV infected pea, PeVYV-3 infected eggplant, PeVYV-1 infected pea and broad bean, CABYV infected tobacco and pea. Moreover, the occurrence of SABYV in Yunnan Province was first reported. The host range of poleroviruses is gradually expanding, especially in various parts of Yunnan, indicating that the harm of poleroviruses to crops is gradually increasing. In addition, there is a risk of disease outbreaks with umbravirus co-infection. The research results contribute to a deeper understanding of the main types, distribution, and occurrence trends of poleroviruses in Yunnan, providing reference for comprehensive prevention and control of plant diseases caused by poleroviruses and their combined infection with umbraviruses.

Diseases caused by oomycetes pose a substantial risk to agricultural production, establishing this pathogen as a principal research and control focus within agroforestry. To explore the status quo and future direction of the field of oomycetes, we used the Web of Science as our data source and conducted a bibliometric analysis of oomycete-related literature from 1985 to 2023. Additionally, CiteSpace was employed to create a knowledge graph, providing a visual representation of the findings. The publication volume analysis indicates a predominant research presence in countries such as the United States, China and Germany. Notably, China has demonstrated remarkable growth over the last five years, ascending to global prominence in this field by 2022. In terms of institutional contributions, the US Department of Agriculture, Nanjing Agricultural University, and the University of California system emerge as leading entities, both in publication volume and the impactful nature of their research. The hotspot analysis delineates that the field predominantly investigates ten specific types, including the Pythium spp., Phytophthora infestans, Ph. capsici and so on. Key research themes include systemic acquired resistance, climate change impact, and antibacterial activities. Furthermore, cluster analysis of literature co-citation unveils several evolving significant research directions within the oomycete fields, represented by RXLR effectors, convergent evolution, and virulence factors. Moreover, a detailed examination of highly cited literature underscores the raising interest in factor pathogenic mechanisms of effector, prevention and control of disease, biological control and immune signal regulation . These works are beneficial for new researchers of oomycetes to quickly understand the current research status and cutting-edge hotspots in this field, and provide some reference for predicting potential research directions of oomycetes.

Southern corn rust caused by Puccinia polysora Underw., is a fulminant and airborne disease, which can cause serious losses during epidemic years. Many studies at home and abroad have shown that the physiological races of P. polysora were very abundant, and the epidemic of plant diseases was mainly caused by the dominant races of P. polysora, but there were few research reports on the physiological races of P. polysora in China, so it brings many difficulties to the prediction and prevention of this disease, and has become a bottleneck in corn production. Based on the current research on the resistance genes and resistant inbred lines of southern corn rust in China, this study selected inbred lines containing known resistance genes and backbone inbred lines in maize production as differrential to be identified. Isolates of southern corn rust collected from different regions were used to identify these inbred lines resistance at the seeding in greenhouses, and the virulence frequency (VF) of different inbred lines. Then the inbred lines with the ability to identify different pathotype were selected to construct a set of differrential, and the pathotypes of southern corn rust in China was studied. 14 pathotypes were identified. Among them, pathotype 1, which can only infect Huangzaosi, with the highest frequency of 0.58, was the dominant pathotype of P. polysora in China, which could be found from 7 provinces such as Hainan, Guangxi, Guangdong, shandong, etc. in 2016 and 2017. This pathotype, which can be determined as a new physiological race of southern corn rust pathogen in China. This is the first physiological race of P. polysora identified in China, temporarily named as Nanzhong1(NZ1).

Rice blast fungus has diverse polymorphism in paddy fields. To clarify the role of genetic recombination on biodiversity of Magnaporthe oryzae population in paddy fields, 336 single-spore isolates of M. oryzae were collected from five main rice-producing regions of Liaoning Province, and their difference on mating type distribution and fertility capacity were analyzed. The PCR amplification on mating type genes showed that all 336 isolates belonged to the same mating type, MAT1-2. The confrontation cultivations of all isolates with a standard strain P9 having an opposite mating type (MAT1-1) showed that the average proportion of fertile strains was 37.5% and the average number of perithecia of each cross was 38.8. Moreover, the fertility capacities of the isolates from the five main rice-producing regions were significantly varied. Taken together, these findings suggest that sexual reproduction of M. oryzae population in Liaoning Province is rare or probably non-existent though they retain certain fertility capacities, and the biodiversity of M. oryzae population in paddy fields may be attributed by other factors.

Late blight caused by Phytophthora infestans seriously affects the yield and quality of tomato. Previous research found that tomato plants contain age-related resistance (ARR) to P. infestans, but the underlying mechanisms are still unclear. Here, we used tomato variety ‘Micro Tom’ as the tested material and found that younger (4-week-old) plants are more resistant while older (8-week-old) plants are more susceptible to late blight. Through RNA sequencing and real-time quantitative PCR (qPCR) analysis, we observed that the transcription levels of genes involved in jasmonic acid (JA) synthesis, such as AOS1, AOS2 and AOC, are higher in 4-week-old plants than those in 8-week-old plants. We further examined the levels of several phytohormones and found that the concentration of JA in 4-week-old plants is significantly higher than that in 8-week-old plants. Transient expression of AOS1, AOS2 or AOC in tobacco leaves made them more resistant to late blight, suggesting that these JA biosynthetic genes can enhance tomato resistance to late blight. Tomato plants sprayed with MeJA were more resistant whereas tomato plants sprayed with JA synthesis inhibitor DIECA were more susceptible to late blight, suggesting that JA positively regulates tomato resistance to late blight. Thus, we provide evidence supporting a model in which genes involved in JA synthesis play important roles in the age-related resistance to late blight in tomato. Our results lay an important basis for using ARR to control tomato late blight.

Fusarium crown rot, mainly caused by Fusarium pseudograminearum, is a destructive disease in wheat production. To establish a rapid and reliable detection method for F. peasudeograminearum, the specific PCR primer pair (Fpg-F1/R2) was designed based on the RPB sequence, and real-time fluorescence quantitative PCR (qPCR) was used to validate the efficiency of the primer. The results showed that the primer pair had high specificity and sensitivity of 100 pg of DNA. Furthermore, the qPCR system for early and rapid detection of F. peasudeograminearum had an amplification efficiency of 87.5% and correlation coefficient of 0.99, and the pathologic threshold of F. pseudograminearum in soil was determined by using this detection system. It was found that F. pseudograminearum could cause Fusarium crown rot when the DNA concentration of F. pseudograminearum in field soil exceeded 213 pg·g-1. Hence, the qPCR-based method we developed for F. pseudograminearum detection has the advantages of high specificity and sensitivity, and can be used for rapid and early detection of F. pseudograminearum even in field soils.

The basal stem rot disease of belladonna (Atropa belladonna) occurred severely in the experimental farm of Shijiazhuang Academy of Agriculture and Forestry Sciences in May 2022. In order to effectively control the disease, identification, biological characteristics of the pathogen as well as disease control were carried out. The pathogen isolates causing belladonna basal stem rot disease was identified as Pythium aphanidermatum based on the morphological characteristics, rDNA-ITS sequence analysis and Koch's postulates testing. To our knowledge, the new disease is the first report in China. The optimum temperatures of mycelium growth, sporangium production and oospore formation were 35 ℃, 25-35 ℃ and 35 ℃, the optimum pH values were 7.0-9.0, 7.0-8.0 and 10.0, respectively. In addition, the optimum light condition and growth medium for culturing P. aphanidermatum were determined. The most suitable carbon sources of mycelium growth and sporangium production were soluble starch and glucose, and the most suitable nitrogen sources were ammonium nitrate and urea. Toxicity of nine chemical fungicides and one biological fungicide on mycelium growth of P. aphanidermatum were evaluated in the laboratory condition. The results showed that 35% metalaxyl-M FS, 250 g·L^-1 azoxystrobin SC, 98% hymexazol SP and 100 g·L^-1cyazofamid SC had strong inhibition abilities against the pathogen with EC₅₀ of 1.619, 2.069, 37.463 and 49.484 μg·mL^-1, respectively. All the work mentioned above provided a basic knowledge for rational control of belladonna basal stem rot.

Rhodococcus fascians is a gram-positive actinomycete that can cause plant diseases with a very wide host range. The pathogenic strains of Rhodococcus fascians make abnormal plant tissues form, such as leaf gall, cluster, flat stem, which affects plant growth and causes serious economic losses. As the identification and classification of the genus Rhodococcus were complex and is often confused with other plant diseases with similar symptoms, resulting in few studies being carried out. This review outlines the classification status, biological characteristics, pathogenic mechanisms, disease symptoms, isolation and identification methods, transmission routes of infection and prevention and control measures of R. fascians. It is expected to provide a reference for related research and precise prevention and control of leafy gall disease caused by R. fascians.

Potato Early Blight (PEB) is an important disease of the foliage of potatoes during the growing season and is widespread in all major potato producing areas worldwide. At present, there are no specific agents and potato varieties resistant to the disease completely. In this study, we identified the main cultivar ‘Cooperation-88’ (C88) in Yunnan Province was resistant to the potato early blight caused by Alternaria solani inoculated on leaves in comparison with the susceptible variety ‘Désirée’ by AUDPC. High-throughput RNA-seq in ‘Cooperation-88’ after infection at the early (A. so_e, 0-72 h), middle (A. so_m, 73-120 h) and late (A. so_l, >120 h) stages was performed on Illumina HiSeq PE150 platform. Transcriptome analysis revealed a total of 13 083 genes expressed differentially at A. so_e, of which 7 438 were up-regulated and 5 645 were down-regulated. At A. so_m, a total of 12 121 genes was differentially expressed, of which 3 299 were up-regulated and 8 822 were down-regulated. At A. so_l, a total of 10 530 genes was differentially expressed, of which 1 686 were up-regulated and 8 844 were down-regulated. A set of 2 720 identical genes was found in all the three periods, while 4 997 genes specific to A. so_e, 3 975 genes specific to A. so_m and 3 230 genes specific to A. so_l. Based on gene ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and qRT-PCR validation along with the results of electron microscopic observations, it was speculated that the increased synthesis of pectin lyase and cellulose synthetase was involved in cell wall remodeling of ‘C88’ in the early stage of A. solani infection. The expression levels of glutathione S-transferase and cytochrome P450 were significantly up-regulated in ‘C88’ at mid-infestation, which were involved in the detoxification pathway. Late synthesis of large amounts of antioxidants to stimulate defence mechanisms. In the three periods, high expression levels of transcription factors, such as bHLH, ZIP, MYB, ERF, etc, associated with disease resistance and extensive involvement in the ubiquitination pathway. Overall, our findings could provide a theoretical basis for research on the early blight resistance in potato and accelerate the resistance breeding.

The application of molecular marker assisted breeding is limited in rice, which due to unclear resistance gene composition in most rice parent materials and the highly homology of allelic genes. In this study, we designed the functional nucleotide polymorphism markers for Pikp-1, Pikh-1, Pik-1, Pikm-1 and Pi1-1 at the specific polymorphism sites, respectively. Those sites were screened by the allelic genes alignment and then picked out the most specific sites by blasting with 155 rice genomes at Rice Resource Center. Based on those markers, we examined 24 monogenic lines and 109 rice parent lines which using for rice breeding in Sichun basin, and finally identified Pik-1, Pikh-1, Pikp-1, Pi1-1, and Pikm-1 gene from 0, 1, 5, 14, and 20 rice parent lines. Among them, the Pi1 gene was identified by sequencing in ‘Mianhui 365’, which verified the functional markers can distinguish those allelic genes at Pik site, effectively and accurately. It identified a number of rice parent resources with definite resistance gene composition at Pik site and provided reliable molecular markers for Pik-1, Pikh-1, Pikp-1, Pi1-1, and Pikm-1 gene.

In 2022, a study investigating viral diseases in three watermelon planting plots was conducted in Jiyuan, revealing an average incidence rate of approximately 97%. Twenty samples, comprising 14 watermelon samples, 4 melon samples, 1 pumpkin sample and 1 pigweed (Amaranthaceae retroflexus L.), were collected from the field. Three watermelon samples and one Amaranthaceae weed sample underwent small RNA sequencing, separately, and virus detect identified seven viruses from the four small RNA sequencing data sets. Subsequently, RT-PCR using primer pairs specific for 16 watermelon-infecting viruses identified the same seven viruses in all 20 samples. Watermelon mosaic virus (WMV) and zucchini yellow mosaic virus (ZYMV) had detection rates of 100% and 85%, respectively, making them the two most prevalent viruses in watermelon fields. WMV was also identified in pigweed, which could serve as an intermediate host of WMV in the field. The full genome sequences of four WMV isolates were derived from four data sets of small RNA sequencing. Comparing the identity and conducting a phylogenetic analysis based on the full genome sequences of WMV revealed that WMV isolates from Jiyuan have very high genetic diversity, suggesting that there could be multiple initial infection sources of WMV in the region. This study identified the causal agents of viral diseases in watermelon in Jiyuan; established a theoretical foundation for developing prevention and control strategies and conducting epidemiological research on viral diseases in watermelon in the region.

Citrus bacterial canker caused by Xanthomonas citri subsp. citri (Xcci) is an important bacterial disea-se of citrus plants. Our previous work revealed that the homologous of XAC3126 (Accession no. AAM37971.1) of Xcci strain 306, which was predicted to be a single-domain response regulator, might be involved in the bacterial virulence in Xcci Guangxi wild-type strain N8. To investigate the biological functions of this gene (named embR), a deletion mutant was constructed with strain N8 as the starting strain. Simultaneously, a complemented strain was constructed using a recombinant plasmid harboring this innate gene. Phenotypic analysis revealed that the embR deletion mutant ΔembR showed obviously reduced virulence on the host plant Citrus reticulata Blanco 'Orah' compared with the wild-type strain, while the complemented strain exhibited similar virulence with that of the wild-type strain. Additionally, the ΔembR mutant displayed an obvious reduction in extracellular polysaccharide (EPS) production, cell motility and cell aggregation. Reverse transcription quantitative real-time PCR (RT-qPCR) revealed that the transcript level of a set of genes involved in EPS production and cell motility in the ΔembR mutant was decreased compared with that in the wild-type strain. These combined data indicate that the embR gene is required for multiple cellular processes including virulence in Xcci and modulates the expression of a series of virulence factor-related genes.

The occurrence of Fusarium crown rot (FCR) caused by Fusarium pseudograminearum has been becoming increasingly serious in China, which has posed a severe threat to wheat yield and quality. The SEY1 belongs to the RHD3 (Root Hair Defective 3) family and encodes a dynamin-like GTPase protein participating in endoplasmic reticulum (ER) fusion. The ER is involved in the synthesis of deoxynivalenol (DON) in different pathogenic fungi, while its function in F. pseudograminearum has not been reported. In this study, subcellular localization of GFP-tagged Sey1 (FpSey1) protein in F. pseudograminearum was observed, and the results showed that FpSey1 was localized in the ER. The FpSEY1 deletion mutant (ΔFpSey1) was generated through PEG-mediated protoplast transformation and verified by Southern blot analysis, and complemented strains were obtained as well. Compared with the wild-type strain, the ΔFpSey1 mutant exhibited significant reduction in vegetative growth, conidiation, relative expression of DON biosynthesis related genes (TRI1, TRI5, TRI10) , and the virulence on wheat coleoptiles and barley leaves. In addition, the ΔFpSey1 mutant is more sensitive to salt stress, hydrogen peroxide (H₂O₂), but more tolerant to dithiothreitol (DTT) than the wild-type and complemented strains. These results indicate that FpSey1 localized in the ER plays important roles in the growth and infection of F. pseudograminearum.

Root-knot disease, caused by Meloidogyne incognita, seriously threatens the production of many crop plants. To further explore biocontrol resources for this disease, two bacterial strains showing nematicidal activity were isolated from vegetable rhizopsheric soil in Yangzhou City, China. These two strains, named HJ03 and HJ04, were identified as Bacillus amyloliquefaciens and B. safensis, respectively, based on their morphologi-cal characteristics, biochemical properties, and phylogenetic analysis results. The corrected mortalities of HJ03 and HJ04 cell suspensions against second-stage juveniles (J2s) of M. incognita after 24 h of treatment were 77.3% and 79.3%, respectively, while those for culture filtrates of the two strains were 75.9% and 80.1%. No significant difference in corrected mortalities was observed between treatments with cell suspension and culture filtrate. Cell suspensions of HJ03 and HJ04 cultured for 24 h showed good nematicidal activity, and extended culture time did not significantly increase nematicidal activity. Cell suspensions (OD₆₀₀=1.2) of HJ03 and HJ04 diluted to 1:2 resulted in mortalities of 77.7% and 78.6%, respectively, similar to those caused by their mother solutions, but showed significantly decreased mortalities when diluted to 1:5. The biocontrol mechanisms of HJ03 and HJ04 against M. incognita were revealed as follows: HJ03 and HJ04 can inhibit egg hatching of M. incognita, with inhibition rates of 71.1% and 64.0%, respectively, compared to LB medium-treated control; significantly inhibit the chemotaxis of J2s. The number of J2s in tomato rhizosphere (1 cm) treated with HJ03 and HJ04 was reduced by 90.9% and 87.6%, respectively, compared with that of control; dramatically inhibit nematode infection, with inhibition rates of 85.4% and 85.2%, respectively, after treated with HJ03 and HJ04 for one week; inhibit gall formation, with gall indexes of 1.1 and 1.6 for HJ03 and HJ04, respectively, at 40 d after treatment, whereas 3.3 for control; inhibit the formation of egg masses, with inhibition rates of 75.7% and 73.1% for HJ03 and HJ04, respectively, at 60 d after treatment; reduce the size of M. incognita-induced giant cells. In addition, HJ03 and HJ04 can promote seed germination and seedling growth of tomato. This study enriches the biocontrol resources against root-knot disease and lays a basis for further development of biocontrol agents.

In recent years, apple diaporthe neck and root rot has become one of the most important limiting factors for the development of apple production in Yunnan Province. In this study, the typical disease samples were collected and the fungal isolate M2g7-1 was obtained by tissue separation approach. The purified culture M2g7-1 was preliminary determined belonging to Diaporthe spp. based on the morphological features of colony, pycnidia, cirrus, two forms of conidia. The pathogenicity of M2g7-1 was further validated on apple young branches to fulfill the Koch's law. The taxonomic of pathogen M2g7-1 has been further determined with combining molecular phylogenetics. The phylogenetic tree was created with the data set of sequences from the internal transcribed spacer (ITS) of ribosomal DNA, the histone H3 (HIS) gene, the translation elongation factor 1-alpha (TEF) gene, and the beta-tubulin (TUB) gene. Based on morphological and molecular biology analysis, the pathogen M2g7-1 was finally identified as Diaporthe eres. This is the first report of D. eres as the pathogen of apple diaporthe neck and root rot. The research results provide a theoretical basis for the epidemic research and comprehensive control of this disease.

Leucine-rich repeat receptor-like protein kinases (LRR-RLKs), a typical type of receptor-like kinase in plant, play important roles in response to pathogen infection. To clarify basic characteristics of the LRR-RLK family members in foxtail millet and their roles in resistance to infection by Sclerospora graminicola, members of this gene family in foxtail millet were identified, and their evolutionary pattern, sequence characteristics, gene structure, promoter sequence and expression pattern were analyzed by bioinformatics method. Meanwhile, the transcriptome data of resistant and susceptible foxtail millet varieties infected with S. graminicola were obtained at 3 different growth stages, and the co-expression modules of resistance gene and the core genes were identified via the weighted gene co-expression network analysis (WGCNA). The results showed that the LRR-RLK genes were distributed on overall 9 chromosomes of foxtail millet. A phylogenetic analysis was conducted on LRR-RLK genes from foxtail millet and Arabidopsis, and the result indicated that they were mainly divided into 4 categories. Structural analysis displayed that their kinase domains were relatively conservative. The promoter regions of these LRR-RLK genes contained multiple cis-acting elements related to defense and stress responses as well as meristem expression, indicating their involvement in multiple biological processes. A co-expression network of resistance-related genes was developed by using WGCNA. Of 44 gene co-expression modules that were identified, 3 (Turquoise, Blue and Yellow) were specific modules associated with resistance to S. graminicola, from which 12 core genes were identified. Functional annotation showed that these genes were involved in plant disease resistance. Further RT-qPCR analysis of the 6 core genes (Seita.9G413000, Seita.9G296000, Seita.9G557200, Seita.9G493600, Seita.3G241700 and Seita.9G163200) confirmed that they were induced in response to S. graminicola infection, indicating that these core genes may play important roles in resistance to the pathogen infection. The results provide a valuable reference for further revealing the molecular mechanism underlying the resistance of foxtail millet to S. graminicola.

After annotating the genome of Xanthomonas oryzae pv. oryzae strain PXO99A-GX, we found an atypical chemoreceptor gene PXO_01024, which encodes a protein with two transmembrane domains (TMD) and a methyl-accepting domain (MA) but without the ligand-binding domain (LBD). To understand the biological function of PXO_01024, we constructed the PXO_01024 deletion mutant DM01024 and its complemented strain CDM01024 by homologous double exchange method. Deletion of PXO_01024 resulted in the reduced formation of biofilm and almost loss of bacterial swimming, while in CDM01024 the swimming motility and biofilm formation ability were restored to wild-type levels. The virulence of DM01024 was not significantly different from that of the wild-type strain when inoculation of wounded host plants was performed. However, when unwounded plants were inoculated with the spraying inoculation method, the disease index caused by DM01024 was significantly reduced compared with that caused by the wild-type strain and complemented strain CDM01024, indicating that PXO_01024 played a role in early infection of Xoo. The chemotaxis of these strains was subsequently detected by capillary method, and the results showed that DM01024 showed significantly reduced chemotaxis to methionine, alanine, leucine, glycine, asparagine, phenylalanine, isoleucine, glucose, maltose, xylose, fructose, succinic acid, and tartaric acid compared with the wild-type strain. This study demonstrated that the atypical chemotactic receptor gene PXO_01024 is associated with chemotaxis, swimming motility, and early infection of Xoo.

Powdery mildew is a common disease on Coreopsis lanceolata, which affects the growth and deve-lopment of the plant and reduces its ornamental value. From 2022 to 2023, powdery mildew occurred seriously on Coreopsis lanceolate in Beijing. In this study, typical morphological characteristics of the pathogenic isolates were analyzed, and a phylogenetic tree was constructed based on the ITS sequence. The results showed that the isolates were identified as Podospaera fusca. This is the first report of Coreopsis lanceolata powdery mildew in Beijing, which will contribute to the control of powdery mildew on Coreopsis lanceolata.

To investigate the incidence and population genetic diversity of tomato zonate spot virus (TZSV) on tobacco in Yunnan, 560 samples of tobacco plants exhibiting symptoms of spot wilt were collected from various tobacco regions in this province. A pair of specific primers from the nucleocapsid protein (NP) gene were used to screen the samples. NP gene of the selected TZSV-positive samples was cloned, sequenced, and employed for phylogenetic, analyses, assessment of genetic diversity and determination of population differentiation. The results of RT-PCR showed that 262 out of the 560 samples were found to be infected with TZSV, with a mean positive detection rate of 46.8%. A significant recombination signal within the genome of the DX_LJHP_65 isolate was identified through recombination analysis. Phylogenetic analysis showed that 129 TZSV isolates can be divided into 6 groups, which tended to cluster according to their geographical origin, suggesting that the evolution of TZSV exhibits a pronounced geographical specificity. The mismatch distribution analysis results for the TZSV population in Yunnan indicated a multimodal distribution, suggesting that it has not undergone recent demographic expansion. The analysis of genetic differentiation among populations revealed a significant difference in gene exchange patterns. Specifically, the frequency of gene flow between the DX and DDB populations and other populations is found to be very low. On the other hand, there was frequent gene exchange observed between the remaining populations. This study is the first report on the genetic variation of TZSV isolate populations in various tobacco regions of Yunnan. It offers crucial insights that serve as a valuable reference for the prevention and control of TZSV.

The nucleic acid sequence encoding the CI protein of potato virus Y (PVY) had multiple regions similar to prokaryotic promoter elements. It was possible to translate toxic proteins in prokaryotic cells, so it was difficult to construct vectors. According to the codon bias of prokaryotes, the CI sequence was modified without changing the amino acid sequence. The expression vector containing CI open reading frame (ORF) was successfully constructed, and CI protein was successfully expressed through the eukaryotic cell-free protein expression system. Six cell lines were prepared by immunizing Balb/c mice with purified protein using hybridoma technology. Indirect ELISA and western blot showed that the prepared CI monoclonal antibody 4B7_2D6(IgG1) had high sensitivity and specificity. The successful expression of CI protein provides a prerequisite for the purification of CI protein and the subsequent study of the structure and function of CI protein, which is of great significance for further exploring the interaction mechanism between CI and plant proteins.

A cosmetic defect on fruits of citrus Orah ((Citrus tangerina × C. sinensis) × C. tangerina) and Shatangju (Citrus reticulata Blanco cv. Shatangju) outbreaks in Southern China recently. As necrosis of outer layer cells in the green pericarp of fruits, the symptoms looked like ringworm or tinea, the name of “white scaled blotch” was given. However, as the etiology of the disease has not been determined, the strategy for prevention and control of this disease was confusion. In this study, field investigation was token and samples were collected from more than 10 orchards in the Guangxi and Guangdong provinces during 2020 to 2022. The pathogen was isolated on the infected pericarp, and its pathogenicity was confirmed with Koch’s postulates. Based on morphology and phylogenetic analysis of thecombined sequence data of LSU, ITS and rpb2, the pathogen was identified as Zasmidium fructicola. The determination of etiology lays a foundation for the study of epidemiology and to guide prevention and control of this disease.

In 2021, typical leaf samples of Rosa chinensis black spot disease were collected from the South Tropical Garden in Kunming, Yunnan Province, China, and a strains were obtained by tissue isolation method. According to Koch's rule, morphological characteristics and phylogenetic analysis of ITS, TEF1 and TUB gene sequences, the pathogen was identified as Gnomoniopsis rosae. This is the first report that G. rosae caused R. chinensis black spot disease in China.

Meloidogyne enterolobii, which is highly pathogenic to a wide range of host plants and spreads rapidly, can cause devastating damage to many crops. To deeply analyze the pathogenic mechanism of this nematode, here we take T106, a gene specifically induced in tomato roots in response to M. enterolobii infection based on previous transcriptome data, as our target. We silenced T106 in tomato plants via TRV virus-induced gene silencing technology, and then inoculated tomato seedlings with M. enterolobii to observe the difference in nematode and giant cell development in root system between T106-silenced and T106-unsilenced plants. The results showed that the silencing vector we constructed could effectively silence T106 gene in tomato plants, with a silencing efficiency of 85%; compared with T106-unsilenced control plants, there was no significant decrease in the percentage of root knots in T106-silenced plants, but the development of M. enterolobii in root knots was inhibited, and the number of eggs produced by M. enterolobii was reduced by 79.3%; meanwhile, the area occupied by giant cells was also decreased. In summary, T106 might be a susceptible gene targeted by M. enterolobii. Exploration of such susceptible genes in plants is vital for finding new ways to control root-knot nematodes including M. enterolobii.

In recent years, wheat scab, corn stalk rot and ear rot caused by Fusarium graminearum have led to substantial losses in crop yields. To investigate the genetic diversity and identify pathogenicity-related genes of F. graminearum, we performed population genetic diversity analysis and selective elimination analysis on 93 F. graminearum strains with released genome-wide resequencing data, using single nucleotide polymorphism (SNP) technology. The resequencing data of these F. graminearum strains were meticulously processed by using the Genome Analysis Toolkit 4 (GATK4), yielding a collection of 3,817,652 SNP markers. Based on these markers, a phylogenetic tree was constructed, and principal component analysis (PCA) and population structure analysis were conducted, effectively partitioning the 93 F. graminearum into 3 distinct groups. The selection elimination analysis of group 1 and group 2 revealed that group 1 exhibited a more pronounced response to selection pressure. A total of 70 regions were identified as candidate sites within the top 5% intersection region of population polymorphism (θπ) and population differentiation index (Fst). Furthermore, 76 protein-coding genes were identified in F. graminearum by leveraging the genomic location information. The results of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that these 76 candidate genes are mainly involved in metabolic pathways. Among them, eight genes (FGSG_05447, FGSG_05610, FGSG_10272, FGSG_10313, FGSG_01353, FGSG_05545, FGSG_10858 and FGSG_12745) are closely related to the pathogenicity of F. graminearum through further gene expression analysis. The result lays a basis for clarifying the pathogenic mechanism of F. graminearum and breeding F. graminearum-resistant wheat and maize varieties.

Rhus chinensis ,also known as Chinese gallnut tree is an important economic tree species in China. In recent years, anthracnose symptoms were found on the branches and rachises of Rhus chinensis at several planting located in Wufeng Tujia Autonomous County, Hubei Province. Initially the brown spots were discovered on the infected tree. As the spots gradually expanded, irregular in shape, multiple spots could be united together into a big one, and the color of the spots gradually turned dark brown to black. Finally, the diseased branches broke off, the leaves and the galls on branches became wilt. Ten isolates were obtained from branches samples and eight of them were identified as Colletotrichum nymphaeae by morphology and multilocus phylogenies from combined datasets of ITS, Tublin, Actin, Gadph, Chs. The assay of Koch’s postulates confirmed that C. nymphaeae was the causal agent of Rhus chinensis anthracnose. To our knowledge, this is the first report of C. nymphaeae causing Rhus chinensis anthracnose in China.

Gray mold disease caused by Botrytis cinerea leads to severe crop yield reduction, and the secreted proteins play significant roles in the fungal infection. However, the functional mechanisms of these secreted proteins in B. cinerea remain largely unknown. In this study, a secreted protein, BcSGP1, from the secretome of B. cinerea during infection stages was identified. The expression level of BcSGP1 was upregulated during infection stages. Deletion of BcSGP1 caused reduction in pathogenicity, but not in growth rate, conidial production, or stress resistance. Transient expression of BcSGP1 in Nicotiana benthamiana leaves using agroinfiltration induced necrosis, and this necrosis-inducing activity depended on the plant receptor-like kinase BAK1, but not the SOBIR1. Furthermore, BcSGP1 could induce resistance against B. cinerea in N. benthamiana leaves. These results suggest that BcSGP1 is a pathogenesis-related secreted protein and involved in inducing plant resistance during the interaction between B. cinerea and plants. This study enhances our understanding of the pathogenic mechanisms of B. cinerea, providing a theoretical basis and genetic resources for effective control of gray mold disease.

Villosiclava virens can infect rice plants and cause rice false smut. At present, it is still controversial whether V. virens overwinters in the form of sclerotia or chlamydospores. In both 2021 and 2022, rice false smut was obviously observed in the rice fields in Xiaoshan District, Hangzhou City, Zhejiang Province. To clarify the overwintering form of V. virens in these fields, the survival of sclerotia and chlamydospores was continuously monitored from October 2021 to November 2022. The results showed that among all soil samples collected for 5 times (9 randomly selected sites in both rice-planting fields and ridges for each time), chlamydospores could be observed by microscope in at least 1 site for each sampling time except for ridge sites for 2 sampling times (January and May of 2022); V. virens could be detected by nested PCR in at least 1 sampling site from both rice-planting fields and field ridges; the survival periods of chlamydospores preserved at 23 ℃ and 4 ℃ were about 7 and 13 months, respectively; chlamydospores in soil samples still had the ability to germinate after storage for 6 months at 4 ℃. From October 2021 to October 2022, no sclerotium was found in our sampling fields and collected soil samples. Only a few sclerotia were found on rice false smut balls on November 9th, 2022. However, the sclerotium-bearing rate of rice false smut balls was only 3.14%. Taken together, it was concluded that V. virens overwintered by the form of chlamydospores in soils of the sampling rice fields in 2021, which became the main primary infection source in 2022 and caused rice false smut.

Viral diseases in cucumber in Qudi are more and more serious in recent years. To detect and identify the main viruses, the plant samples of cucumber were collected from Qudi town, Jiyang district, and next-gene-ration sequencing technology (NGS), RT-PCR amplification and analysis of viral genome sequences were carried out. The results showed that the viruses infecting cucumber in the spring were cucumber green mottle mosaic virus (CGMMV) and watermelon silver mottle virus (WSMoV). Besides CGMMV and WSMoV, cucumber plants in the autumn were also infected with zucchini yellow mosaic virus (ZYMV). The detection rates of CGMMV, WSMoV and ZYMV by RT-PCR were 68.2%, 45.5% and 50.0%, respectively, and the detection rate of complex infection was 50%. Genetic sequence analysis revealed that the coat protein (CP) gene sequence of CGMMV [JY2-6 (GenBank accession number: OR591512) isolated in this study was similar to the sequence of CGMMV [SDRZ (GenBank accession number: KX185151)] isolated from cucumber in Rizhao, and the identity was 100%. The nucleocapsid (N) gene sequence of WSMoV [JY2-4 (GenBank accession number: OR591517) isolated in this study was similar to the sequence of WSMoV [W6412 (GenBank accession number: AM113765)] isolated from watermelon in Thailand, and the identity was 99.1%. The CP gene sequence of ZYMV [JY2-7 (GenBank accession number: OR591522) isolated in this study was similar to the sequence of ZYMV [Yaz.Ashk.S.Z (GenBank accession number: KX495623)] isolated from cucumber in Iran, and the identity was 97%. This study demonstrated that the cucumber in Qudi was mainly infected by CGMMV, WSMoV and ZYMV, and complex infection was also common. This study provided a basis for virus prevention of cucumber in Qudi.

To identify the pathogen causing anthracnose disease on quinoa plants and investigate its biological characteristics, we collected diseased quinoa plants with typical anthracnose symptoms and conducted pathogen isolation and purification experiments. A representative strain LMTJ was obtained and determined as the pathogen of quinoa anthracnose by completing Koch′s postulates. Combined with morphological characteristics and the result of multi-gene phylogenetic analyses (ACT, CHS-1, GAPDH, ITS and TUB2), the pathogen was identified as Colletotrichum spinaciae. The suitable culture condition for mycelial growth of C. spinaciae LMTJ strain is that with starch as carbon source, peptone as nitrogen source, temperature at 20~25 ℃ and pH value of 6.0~7.0, while for sporulation is with sucrose as carbon source, sodium nitrate as nitrogen source, temperature at 20~25 ℃ and pH value of 6.0. To screen effective fungicides for the prevention and control of quinoa anthracnose, the toxicity of 5 fungicides to C. spinaciae LMTJ strain was tested. The results showed that all the tested fungicides could inhibit mycelial growth of LMTJ, of which 92.8% iprodione exhibited the strongest inhibitory effect, with EC₅₀ of 2.7654 mg·L^-1. The results provide scientific basis for the diagnosis and control of quinoa anthracnose.