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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Fusarium sacchari is one of the major pathogenic fungus that cause sugarcane pokkah boeng. In order to explore the function of metalloproteinase effector proteins in F. sacchari, we used the genomic data of F. sacchari to predict the secretory metalloproteinase proteins, and successfully amplified a zinc-type metalloproteinase effector protein gene Fs03538. The results showed that Fs03538 contained a typical ZnMc super family domain, and the 1-18 amino acid sequences at the N-terminal of the protein contain specific signal sequences. Subcellular localization showed that Fs03538 could be localized in the nucleus of Nicotiana benthamiana; qRT-PCR analysis showed that the expression level of Fs03538 was induced and reached the highest peak at 12 h post F. sacchari infection. Agrobacterium tumefaciens mediated transient expression system confirmed that Fs03538 could inhibit the necrosis of tobacco cells induced by mouse Bcl-2-associated X protein (BAX). As compared with the wild type F. sacchari strain CNO-1, the Fs03538 knock-out mutant showed no significant difference on mycelial growth and conidia production, but the pathogenicity on sugarcane was significantly decreased. Taken together, the results of the study suggest that Fs03538 is an important virulence factor of F. sacchari, which highly expressed at the time of infection and could inhibit the host immune responses by entering the host cell nucleus.

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.

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.

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.

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.

Rice is an important grain crop in the world. Although some genes that confer resistance to rice blast and bacterial blight, two important diseases threatening rice production, have been identified in rice plants, the corresponding resistance gene resources remain scarce. In this study, we found that the transcription factor OsEIL4 is involved in regulating rice resistance to these two rice diseases. Quantitative real-time PCR (qPCR) assays showed that the expression of OsEIL4 was markedly induced upon Magnaporthe oryzae (M. oryzae) or Xanthomonas oryzae pv. oryzae (Xoo) infection. Moreover, compared with wild-type rice plants, Oseil4 (CRISPR/Cas9-based OsEIL4 knockout) and OsEIL4-RNAi rice lines were more susceptible, while OsEIL4-OX (overexpression) plants were more resistant to M. oryzae and Xoo. Further qPCR analysis of the transcript levels of the marker genes of ethylene pathway and defense-related genes OsPR1a and OsPR5 exhibited that they were downregulated in Oseil4 lines but upregulated in OsEIL4-OX lines, suggesting that OsEIL4, which functions as a positive regulator in ethylene pathway, mediates rice resistance by modulating PR genes expression. Subcellular localization and yeast-one-hybrid assay results confirmed that OsEIL4 has transcriptional activity, indicating that it may regulate rice disease resistance by exercising transcriptional regulatory function. This study explores a gene resource with broad-spectrum resistance, providing a new possibility for molecular breeding of rice disease resistance.

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.

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.

In order to explore the influence of Polygonatum sibiricum rotation on the soil microbial community of Panax notoginseng, evaluate the restoration ability of crop rotation and natural restoration. The influence of Polygonatum sibiricum rotation on the microbial structure and microflora change of soil continuous cropping with Panax notoginseng was studied. The results showed that seedling rate was 88.33%, significantly higher than the incidence rate of fallow treatment, which was less than 20%, but the difference was not significant. The diversity of soil fungi and bacteria was significantly reduced (P<0.01). The results showed that crop rotation could signi-ficantly affect the β diversity of soil fungi and bacteria in Panax notoginseng (P<0.001), and could significantly increase the relative abundance of Ascomycota and reduce the relative abundance of Basidiomycota and Triguta. Firmicutes, Budlesomonas, Chloritans, Acinetobacter, Bacteroidetes, etc. LEfSe results showed that after the rotation of the pathogens, Fusarium, Ilyonectria, and other fungi. Rhizosphere soil microbial fungi mainly saprophytic, pathological and mixed nutrition mode, after the rotation treatment, plant pathogen fungi abundance, pathogenic bacteria of decline, associated with the disease, at the same time after rotation bacterial L-valine biosynthesis pathway, L-isoleucine biosynthesis I (from threonine) pathway, L-isoleucine biosynthesis II, Aerobic respiration I (cytochrome C) pathway is significantly lower. The rotation of Polygonatum sibiricum can improve soil microorganisms and it’s potential to alleviate the obstacles of Panax notoginseng.

Anthracnose is a common worldwide fungal disease in soybean production, seriously affecting the commercial value of soybean pods as well as seed yield and vigour. In this study, four fungal strains (XZ-1-XZ-4) were isolated from the stalk of a diseased soybean plant within soybean-producing regions of Xuzhou City, Jiangsu Province, using tissue isolation and single spore purification methods. According to morphological chara-cteristics and ITS-TUB2-based phylogenetic analysis results, XZ-1 and XZ-2 were identified as Colletotrichum truncatum, XZ-3 and XZ-4 were identified as Fusarium proliferatum and Fusarium equiseti, respectively. Pathogenicity test results showed that all the four fungi were pathogenic, indicating a complex infection of soybean plants by Colletotrichum and Fusarium phytopathogens in the field. Furthermore, the resistance of 56 soybean varieties/lines to C. truncatum strain XZ-1 was evaluated by using two different inoculation methods (i.e., inoculation of fresh soybean pod with mycelial suspension, inoculation of etiolated hypocotyl with mycelial plug). It was showed that disease indexes obtained by the two inoculation methods were slightly different, but the resistance grades were almost the same, with a match rate of 92.9%. Of these 56 soybean varieties/lines tested, 3 were identified as resistant and 19 moderately resistant; No highly resistant varieties were found, and only 39.3% of the varieties were resistant to soybean anthracnose. This study combines the results of the above two inoculation methods to rapidly and accurately identify the resistance level of soybean varieties (lines) to anthracnose, laying a foundation for screening and utilizing resistant soybean germplasms, and for identifying anthracnose-resistant genes in soybean.

PilZ domain-containing proteins are the largest known receptors of second messenger c-di-GMP in bacteria, but the functions and underlying mechanisms have not been reported in Pseudomonas syringae pv. actinidiae (Psa). To reveal the contribution and regulation mechanism of PilZ domain-containing proteins to the pathogenicity of Psa and to provide new ideas for controlling kiwifruit bacterial canker. Firstly, genome analysis and sequence alignment of Psa M228 were performed to identify the PilZ domain-containing proteins of Psa and analyze the conserved c-di-GMP binding motif. Then, homologous recombination was used to construct deletion mutants, and the pathogenicity, motility and growth between mutants and wild type were determined by leaf discs vacuum infiltration, soft agar plate assays and growth curve measurment, respectively. The transcripts of pathogenicity- and motility-relative genes in WT and ΔPsa_2195 mutant were measured by qRT-PCR. The results show that there are eight PilZ domain-containing proteins in Psa M228, among them PSA_2195 and PSA_1975 have neither a conserved RxxxR motif nor a (D/N)xSxxG binding motif that binds to c-di-GMP. The pathogenicity of ΔPsa_1116, ΔPsa_2195, ΔPsa_2203, ΔPsa_762, ΔPsa_4490 and ΔPsa_4763 were significantly reduced. Deletion of PSA_1116 and PSA_2195, PSA_3989, PSA_762 affected swimming motility and swarming motility, respectively. The growth curve of all mutants are no significant difference with wild type M228. Among all PilZ domain proteins, PSA_2195 regulates the transcription of flagella genes flgA, filE and T3SS genes. Taking together, our research revealed the function of eight PilZ domain-containing proteins in regulating pathogenicity and motility of Psa and the simple molecular mechanisms of PSA_2195.

In this study, the fungal strain LD-11 was isolated from the infected plant of Lonicera caerulea (cv Lanjingling) collected in the horticulture experimental station of Northeast Agricultural University, Harbin, Heilongjiang Province. The strain was identified as Epicoccum nigrum by morphology, rDNA-ITS, LSU, TUB, RPB2 gene sequence amplification and phylogenetic tree construction. The experimental results showed that E. nigrum LD-11 could grow on PDA, OA and MEA medium. The optimal culture medium was OA, and the optimal culture conditions were growth temperature of 25 ℃, pH 6, carbon source is starch and nitrogen source is yeast extract, and full light conditions were conducive to mycelial growth. This study is the first time to isolate and identify E. nigrum, the pathogen of leaf spot disease in L. caerulea, which will provide an important source of pathogenic fungi for future research on control of plant disease.

From 2021 to 2022, jasmine plants with virus-like symptoms of mosaic, yellowing, chlorosis, ringspot and mosaic were observed in Yuanjiang county, Yuxi city and Chenggong district, Kunming city in Yunnan Province, and a total of 95 symptomatic jasmine samples were collected. RT-PCR detection was performed using the virus universal primers of genera Begomovirus, Luteovirus, Polerovirus, Potexvirus, Potyvirus, Tobamovirus and Umbravirus, and the specific primers of cucumber mosaic virus (CMV), jasmine mosaic-associated virus (JMaV), jasmine virus C (JaVC), jasmine virus H (JaVH), jasmine virus T (JaVT) and tobacco streak virus (TSV) for the diseased jasmine samples. The results showed that the diseased jasmine samples collected in Yuanjiang county of Yuxi city and Chenggong district of Kunming city were infected with JaVT, JaVH, JMaV, JaVC and CMV with the detection rates of 60.00%, 57.89%, 15.79%, 13.68% and 6.32%, respectively. JaVT and JaVH were the dominant viruses infecting jasmine in Yunnan. All the five viruses occurred in Yuanjiang and Chenggong, and the dominant viruses in these two regions were JaVH and JaVT. Meanwhile, the virus detection rate in Chenggong was lower than that in Yuanjiang. Viruses mostly cause damage to jasmine in the form of mixed infection, with 11 types of co-infection in the 5 jasmine viruses. JaVC and CMV are usually co-infected with viruses such as JaVH and JaVT. The co-infection of JaVH+JaVT had the highest detection rate at 26.31%. This study was the first to detect CMV infection in jasmine. To gain deeper insights into the molecular variation and phylogenetic relationship between the CMV jasmine isolate (CMV-YYJMLH) obtained from Yunnan Pro-vince and other CMV isolates found in different regions and host plants, the cp gene sequence of CMV-YYJMLH isolate (GenBank accession number: OQ870529) was compared and analyzed with those of 35 other CMV isolates documented in the GenBank. The results showed that isolate YYJMLH shared 77.17%-99.09% nucleotide (nt) sequence identity with other CMV isolates, among them, isolate YYJMLH had the highest nt sequence identity of 99.09% with the CMV pepper isolate (GenBank accession number: MT786689) from Yunnan province. A phylogenetic tree was constructed using the cp gene sequences of different CMV isolates, and results showed that the CMV-YYJMLH jasmine isolate belonged to CMV subgroup I, and the YYJMLH isolate had the closest genetic relationship with the CMV pepper isolate (GenBank accession number: MTT86689). To our knowledge, this is the first report of CMV naturally infecting jasmine worldwide and the first record of JaVT in Yunnan province.

Citrus is one of the most important fruits in China and is cultivated extensively in southern China. Fusarium fujikuroi has been reported to cause diseases on various plants excluding citrus worldwide. In this study, by using tissue separation method, 23 Fusarium-like isolates were isolated from diseased citrus leaves from eight different citrus planting areas in Hubei province. STJ-4 was selected as a representative isolate for further analysis, which included analyses of morphological characteristics, partial sequences of ITS, EF-1α, and RPB1 genes, phylogenetic trees based on the three genes and pathogenicity. Results showed that the STJ-4 isolate was identified as F. fujikuroi, which is the first report of F. fujikuroi causing leaf rot disease on citrus. Our study is important for developing the prevention strategies against F. fujikuroi in the future.

To study the species and genetic variation of yam viruses in Henan province, 188 yam samples suspected of viral diseases were analyzed by high-throughput sequencing and RT-PCR. The results showed that five viruses were detected from yam samples: Japanese yam mosaic virus (JYMV), youcai mosaic virus (YoMV), yam latent virus (YLV), broad bean wilt virus 2 (BBWV 2) and yam yellow spot mosaic virus (YYSMV). The detection rates of JYMV, YoMV, YYSMV, BBWV 2 and YLV were 94.15 %, 87.23 %, 68.09 %, 42.02% and 29.79 %, respectively. 98.94% of the yam samples had complex infection. In this study, there were 20 complex infection types in 188 samples, among which JYMV + YYSMV + YoMV was the main complex infection type, and the detection rate was 26.60 %. Molecular variation analysis showed that YoMV and JYMV were more highly conserved, followed by YYSMV, YLV and BBWV 2, which showed more variation. Phylogenetic tree analyses indicated that the isolates obtained in this study were closely related to those from the same region. At the same time, HTS analysis results showed that other unclassified virus species were detected on yam, so it is necessary to conduct a comprehensive and systematic study on the types of yam viruses in Henan Province.

Brown rot, caused by Monilinia spp., is a serious threat to both stone fruit and pome fruit, greatly affecting the long-distance transportation and exportation of fruits. Based on genomic and transcriptomic analysis of infection of Monilinia fructicola on peach fruit, it was detected that the expression patterns of MfHMG5 and MfHMG6 genes in early stages of infection were similar, and both down-regulated significantly at 1 h after inoculation and then gradually increased. In order to investigate the biological functions of these two genes, the knockout and overexpression transformants of MfHMG5, and knockout and complemented transformants of MfHMG6 were obtained and the corresponding phenotypes were investigated. It was found that the knockout and overexpression of MfHMG5 gene decreased the growth rate and sporulation ability, but did not affect the pathogenicity of M. fructicola. Knock out of MfHMG6 gene reduced the growth rate, virulence and sporulation ability of M. fructicola, and led to the increased expression of MfHMG5 gene. These results indicated that HMG-box family genes MfHMG5 and MfHMG6 were involved in regulating the growth and pathogenesis of M. fructicola.

Foxtail millet (Setaria italica (L.) Beauv.), a novel model species in C₄ gramineae crops, plays a principal role in food security in Africa and Asia and in the adjustment of the crop planting structure in China. It is sensitive to continuous cropping, which is a serious constraint to the production and the quality. Root rot di-sease is typical for the diseased foxtail millet in continuous cropping fields. In this study, a fungus was obtained from the rotten root millet samples and grouped according to their colony morphology, namely, YDSi-1, YDSi-2 and YDSi-3. According to pathogenic tests fulfilling the Koch’s postulate, YDSi-3 showed a strong pathogenicity for root rot of foxtail millet. Based on morphological and molecular identification, YDSi-3 was identified as Fusarium oxysporum. This is the first report of F. oxysporum causing root rot of foxtail millet in China, and will provide a theoretical basis and technical support for the control on the continuous cropping of foxtail millet in the future.

Fusarium solani, known for its extensive host range, is the causal agent of the destructive root rot disease in agriculture production. Secreted proteins play important roles in the infection of host plants by phytopathogenic fungi. To identify the secreted proteins and effectors in F. solani, we performed an in-depth analysis of the F. solani genome in this study. Among the total 17654 genomic proteins, 1032 proteins were predicted to be the candidate secreted proteins by using SignalP, TMHMM, WoLF PSORT and PredGPI softwares, accounting for 5.85% of the total proteins in F. solani. Among them, 258 proteins were predicated to be carbohydrate-active enzymes (CAZymes) by using the dbCAN3 software, with the glycoside hydrolase family being the most abundant. Furthermore, 185 secreted proteins were predicated to be candidate effectors, with 183 sequences being annotated in the PHI database. By employing a virus-based transient expression system, we investigated the effect of the 5 candidate effectors annotated for increased virulence on BAX-triggered programmed cell death, and the result showed that the two effectors (XP_046140852.1 and XP_046131041.1) could suppress BAX-triggered programmed cell death in N. benthamiana. These findings provide not only an important reference for further analysis of the pathogenic molecular mechanism of F. solani but also a theoretical basis for understanding the interactions between F. solani and host plants.

Anthracnose is one of the most important fungal diseases that pose significant threat to the production of Yunnan red pear cultivar ‘Caiyunhong’. The disease mainly causes fruit rot, resulting in a disease incidence of more than 35% in normal conditions. The causal agent was identified as Colletotrichum fructicola based on the morphological characteristics, phylogenetic relationship inferred from ITS, ACT, TUB and CHS sequences, and the result of pathogenicity test. This is the first report of C. Fructicola causing anthracnose on ‘Caiyunhong’ fruit in China, which provides a theoretical basis for effective prevention and control of the disease.

Bacteria from the genus of Pectobacterium are the important plant pathogens causing significant economic losses worldwide, and the emergence of antibiotic-resistant strains further exacerbates the challenges in Pectobacterium-caused disease prevention and control.This study used Pectobacteriums isolated from different host plants as materials and used plate analysis to obtain streptomycin-resistant strains formed in the wild. Clarify its taxonomic status through genome sequencing and comparative genome research, and streptomycin resistance genes were predicted. The results shown that among the eight strains isolated from different hosts, NJAU2 obtained from Yunnan yellow-flowered calla lily disease strains is highly resistant to streptomycin. NJAU2 genome was 5 062 459 bp in length, with G+C content of 51.83% and N50 length of 306 378 bp, containing 4 568 protein-coding genes. NJAU2 clusters on the same branch as the type strain P. aroidearum SCRI 109^T and the reported strain P. aroidearum PC1 based on the Multi-Locus Sequence Analysis results of 8 housekeeping genes (fliA, fusA, glyA, gyrB, purA, rpoA, rpoS, secY). This result is consistent with the phylogenetic relationship constructed based on the 16S rRNA gene sequence. Furthermore, the Average Nucleotide Identity (ANI) and DNA-DNA Hybridization (isDDH) analysis with various Pectobacterium strains also support this classification. Therefore, the naturally occurring streptomycin-resistant strain NJAU2 is classified as a new species within the Pectobacterium genus: Pectobacterium aroidearum, and named Pectobacterium aroidearum NJAU2. P. aroidearum NJAU2 carrying sets of genes encoding proteins for streptomycin-resistanc in its genome. Comparison with the Comprehensive Antibiotic Resistance Database (CARD) identified 328 genes belonging seven types of drug resistance mechanisms. Moreover, in NJAU2 genome, 15 genes were annotated encoding aminoglycoside antibiotic resistance, including rpsL and gidB that are related to streptomycin resistance. The discovery of P. aroidearum NJAU2 provides new material for research in the direction of streptomycin resistance in Pectobacterium spp..

Cucumber seedling damping-off caused by Pythium aphidermatum is one of the main soil-borne diseases seriously affecting the survival of cucumber seedlings. With the expansion of eggplant cultivation area in greenhouse, the occurrence and damages of the disease are increasing year by year. In this study, a bacterial strain ZF514, capable of producing volatile substance with antagonistic effect against P. aphidermatum, was isolated from rhizosphere soil of healthy cucumber plants in Hangzhou, China. According to morphological cha-racteristics, physiological and biochemical properties, and multi-gene (16S rDNA-gyrA-rpoB) phylogenetic analysis, strain ZF514 was identified as Bacillus velezensis. Strain ZF514 also exhibited significant antagonistic effects on the 5 common phytopathogenic fungi by dual culture on two-section of a Petri dish. The results of pot experiments showed that simulated fumigation treatment of soil with strain ZF514 significantly reduced disease incidence of cucumber seedling damping-off, and the control effect reached 63.69%. In summary, the volatile substance-producing B. velezensis strain ZF514 has potential to be explored as an environment-friendly microbial fumigant against soil-borne diseases.

Colletotrichum higginsianum is the major pathogen of anthracnose in cruciferous plants, which can severely damage the production of Chinese flowering cabbage (Brassica parachinensis) in south China. Scytalone dehydratase (Scd) is a key enzyme in the biosynthesis of DHN-melanin that can affect pathogenicity by mediated DHN-melanin biosynthesis in many plant pathogenic fungi. In this study, we identified a conserved scytalone dehydratase ChScd in C. higginsianum. The expression of gene ChSCD was analysed by using RT-qPCR technology, and it was found that the expression level of this gene was significantly up-regulated during the melanization of the hyphae and appressoria of C. higginsianum. Meanwhile, in order to analyse the biological function of the gene ChSCD, the Agrobacterium tumefaciens-mediated transformation technology was used to construct knockout and complementation mutant strains of the gene ChSCD. The results showed that the knockout of gene ChSCD blocked the biosynthesis of DHN-melanin in C. higginsianum, resulting in the loss of the melanization ability in both hyphae and appressoria, and leading to the significantly reduced in tolerance to cell wall interfering substances and oxidative stresses, the appressorium formation rate, turgor pressure, and pathogenicity of the ChscdΔ mutants. In summary, ChScd plays a crucial role in the biosynthesis of DHN melanin in C. higginsianum, which in turn affects the stress resistance, the formation rate of appressorium, turgor pressure, and the pathogenicity of the pathogen.