Clonostachys species are a group of fungi with various morphological and ecological characteristics, which are widely distributed in a variety of environmental conditions, especially in soil. Because Clonostachys can control plant diseases through direct or indirect mechanisms including antagonism, mycoparasitism, growth promotion and the induction of plant resistance, the application of Clonostachys as a biocontrol agent has attracted much attention. In this review, we summarized the progress in phylogeny and taxonomy of this genus, and the interactions of Clonostachys-plant pathogens and Clonostachys-plants. Then, the application status of Clonostachys was summarized and its application prospect was also prospected. Screening strains with excellent biological control characteristics from Clonostachys fungi will promote their commercialization in agricultural applications.

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.

Asarum plants showing leaf blight symptoms were collected from Xinbin County, Fushun City, Liaoning Province, China. To investigate the causal agent of the disease, pathogenicity test was carried out with XXY-2, a representative fungal strain that were isolated from the diseased plant tissues, and the result showed that it is the pathogen causing asarum leaf blight. Based on morphological characters, strain XXY-2 was identified as Talaromyces brevis. According to the results of multigene-combined (rDNA-ITS+BenA+RPB2) phylogenetic analysis, strain XXY-2 was grouped into the same branch of T. brevis model strains DTO 307^T and CBS 141833^T, further confirming that it belongs to T. brevis. Indoor toxicity tests of 8 fungicides against strain XXY-2 showed that pyraclostrobin and fludioxonil had a better inhibitory effect on mycelial growth of the strain, with EC₅₀ values of 0.0096 and 0.0056 μg·mL^-1, respectively. This is the first report of T. brevis as a pathogen of asarum leaf blight, making a theoretical basis for integrated control of the disease.

Sho1 and Msb2 are respectively four-transmembrane membrane proteins and single-chain transmembrane protein. Resent research shows that they generally exist in fungi,and have conservative structures, including extracellular domain, transmembrane structure and cytoplasmic domain. Sho1 is located in the plasma membrane, and Msb2 is located in the plasma membraneand transported into the vacuole through endocytosis. Different domains of Sho1 and Msb2 bind to various signaling proteins, then participate in different pathways in the MAPK signaling pathway, so as to regulation of fungal growth and stress response. At present, the functions of Sho1 and Msb2 have been reported in Saccharomyces cerevisiae, Candida albicans, Aspergillus fumigatus, Verticillium dahliae, Fusarium oxysporum, F. graminearum, Ustilago maydis, Magnaporthe oryzae, Botrytis cinerea, Cryptococcus neoformans, and Histoplasma capsulatum, that mainly involved in filamentous growth, osmotic stress, oxidative stress, cell wall integrity, temperature response, and virulence regulation of fungi. However, their specific functions have fungal evolution specificity. This paper reviewed the structural characte-ristics of Sho1 and Msb2, summarized and analyzed the functions and action ways of Sho1 and Msb2 in different fungi, in order to provide reference for related research.

Peach latent mosaic viroid (PLMVd) is an important viroid infecting peach trees. PLMVd can cause various leaf symptoms including mosaic, yellowish and calico, etc. At present, the mechanism of PLMVd infection causing mosaic leaves is unknown. In this study, 86 full-length PLMVd sequences, in size of 336-338 nt, were isolated and cloned from the mosaic (M) and asymptomatic (N) leaves of nectarine trees collected in the field in China. By DnaSP 5.0 analysis, 31 haplotype (variant) sequences were obtained in the cloned sequences. The haplotype diversity (Hd) was relatively low as 0.79 for M isolates, while was high as 0.90 for N isolates. Compared with N isolates, sequence analysis showed that the sequence variation of M isolates mainly occurred in five regions of the whole sequence. MY1 haplotype sequence was dominant among those of M isolates, which clustered in phylogenetic group I with a few other variants and shared 89.4% identity with that of P1.148, a typical peach calico isolate. Through a comparative study of PLMVd cDNA infectious clones, gene synthesis and inoculation methods, the infectious PLMVd diploid cDNA clone construction and effective inoculation methods were established. The constructed MY1 diploid cDNA recombinant plasmid can infect the Prunus davidiana Franch systematically and exhibit typical mosaic symptoms after high-stressed stems slashing inoculation. The results will build a foundation for further study about the molecular mechanism of PLMVd inducing peach mosaic symptom.

Watermelon planted in early spring is a characteristic fruit in hot area of Yunnan Province. Its viral diseases are more and more serious in recent years. To detect and identify the main viruses, the plants and fruits samples of watermelon were collected from Menghai county, Xishuangbanna state, and transmission electron microscope (TEM) observation, indirect enzyme-linked immunosorbent assay (ID-ELISA), RT-PCR amplification and analysis of viral genome sequences were carried out. The results showed that the viruses infecting watermelon were watermelon silver mottle virus (WSMoV) and cucumber mosaic virus (CMV). The detection rates of WSMoV and CMV using ID-ELISA were 70% and 20%, respectively, in leaf samples, and of complex infection was 15%. The detection rates of these two viruses by RT-PCR were 100% and 65%, respectively, and of complex infection was 65%. However, the complex infection rate of these two viruses detected by RT-PCR amplification could reach up to 100% in seeds. Phylogenetic analysis demonstrated that the genome sequences of WSMoV [21YV-40(GenBank accession no.:OP617563), 21YV-43(GenBank accession no.:OP867047)] isolated in this study were similar to the squence of WSMoV [Banna-2011 (GenBank accession no.:KM242056)] isolated from Yunnan watermelon in 2016, and the similarity was 99%. The genome sequences of CMV [CMVYN40(GenBank accession no.:OP617565), CMVYN46 (GenBank accession no.:OP617566)] isolated in this study were similar to the sequence of CMV [A27(GenBank accession no.:FN552545)] isolated from watermelon in Thailand, and the similarity was 98%. This study demonstrated that the early spring watermelon was mainly infected by WSMoV and CMV, and complex infection was also common. The complex infection of WSMoV and CMV to both the plant and the seed of watermelon was reported for the first time. This study supplied a basis for virus prevention in the early spring watermelon.

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.

Stripe (yellow) rust caused by Puccinia striiformis f. sp. tritici is a devastating disease on wheat, which seriously affects the security production of wheat. Correct severity assessment is essential for disease forecasting and adopting effective disease management measures to reduce wheat yield losses. To realize accurately assess the severity of wheat stripe rust, in this study, the methods for the severity assessment of wheat stripe rust were investigated based on image processing and an automatic grading system of wheat stripe rust severity was developed. Based on the acquired disease images of single leaves of wheat stripe rust, manual disease image segmentation operations and pixel statistics operations were performed successively with an image processing software, and the segmented leaf region and lesion region images and the pixel numbers of the corresponding whole leaf regions and lesion regions were obtained. According to the obtained pixel numbers, the actual percentages of lesion areas in the areas of the corresponding whole diseased leaves were calculated. Based on image processing technology, four image segmentation methods were utilized to implement automatic segmentation to obtain leaf region images and lesion region images. Then, the results obtained by using the four automatic segmentation methods were compared with those obtained by using the manual segmentation method via the image processing software, and the optimal automatic segmentation method was achieved. Subsequently, based on the percentages of lesion areas in the areas of the corresponding whole diseased leaves obtained by using the optimal automatic segmentation method, the severity of each diseased leaf was assessed according to the midpoint-of-two-adjacent-means-based actual percentage reference range and the 99% reference range of the actual percentages for each severity class of wheat stripe rust, respectively. The results showed that the assessment method based on the 99% reference range of the actual percentages for each severity class of wheat stripe rust was the optimal, with the average accuracy of 88.19%. Finally, by using the optimal automatic image segmentation method and the optimal severity assessment method, in combination with the PyQt5 library, Qt Designer, and PyUIC5 design tools, an automatic grading system of wheat stripe rust severity was developed with the Python language. This study provided a basis for the automatic assessment of wheat stripe rust severity based on image processing technology, and provided methods and ideas for the severity assessments of other plant diseases.

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 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.

In this study, 155 isolates of Fusarium were isolated from the diseased roots of strawberry with the symptom of root rot, which were collected from thirteen provinces, municipalities, and autonomous regions across China from 2021 to 2022. The obtained 155 Fusarium isolates were identified to be eight species (namely F. acuminatum, F. asiaticum, F. commune, F. equiseti, F. fujikuroi, F. oxysporum, F. proliferatum, and F. solani) based on morphological characteristics and sequence analyses of internal transcribed spacer of ribosomal DNA (rDNA-ITS) and translation elongation factor-1 alpha (TEF-1α), with F. oxysporum (108 isolates, 69.68%) being predominant. Results of pathogenicity test confirmed that thirty-one representative isolates belonging to these eight species of Fusarium could induce the symptom of root rot on strawberry roots, showing that they were pathogenic on strawberry roots. The average disease incidence (98.62%) and disease index (79.87) of strawberry roots caused by F. oxysporum were higher than those of the seven other species of Fusarium. To the best of our knowledge, this is the first report of F. asiaticum, F. commune, F. fujikuroi, and F. proliferatum causing strawberry root rot in China.

Myb transcription factors play important roles in the regulation of various biological processes in plants. However, the molecular mechanism underlying their roles in regulating late blight resistance remains elusive. Here, we report the cloning of NbMybl, a Myb-like gene from Nicotiana benthamiana, which has an open reading frame of 753 bp and encodes a protein of 250 aa. NbMybl contains a Myb-like DNA-binding domain. Real-time quantitative PCR (qPCR) revealed that NbMybl was induced by infection with Phytophthora infestans. Subcellular localization analysis showed that NbMybl is located in both the nucleus and the cytoplasm. Silencing of NbMybl by virus-induced gene silencing (VIGS) significantly increased the susceptibility of plants to P. infestans. Transcriptome profiling by RNA sequencing identified 8468 differentially expressed genes (DEGs) with fold change ≥ 2 and FDR < 0.01 between NbMybl silenced and non-silenced control lines in response to P. infestans infection, and the result of RNA-seq was further validated by qPCR with 10 randomly selected DEGs. KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis revealed that a total of 373 DEGs were involved in plant-pathogen interaction, 308 DEGs and 216 DEGs were involved in MAPK signaling pathway and plant hormone signal transduction, respectively. We speculated that these DEGs might be closely related to the reduced resistance of NbMybl-silenced N. benthamiana lines to P. infestans. Our study provides valuable insights into the molecular mechanisms of NbMybl in regulating resistance to P. infestans.

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.

Fungal disease is an important factor restricting the high and stable yield of soybean. In order to clarify the taxonomic status of pathogenic isolates SoyITS1 and SoyITS12 isolated from the diseased soybean roots with the symptoms of root rot, the two isolates were identified on the basis of morphological traits and sequence analyses of translation elongation factor 1-α (EF1-α) and RNA polymerase II beta subunit (RPB2). The results showed that the colonies of isolates SoyITS1 and SoyITS12 were milky white when they were cultured on PDA medium. After 7 d of culture on CLA medium, the conidia were falciform with blunt apical cells and slightly crooked base cells, with 3 - 4 septa, the size of which was (20 - 40) μm× (3.5 - 6.8) μm (n = 50). BLAST sequence comparison showed that the consistency between strains SoyITS1 and SoyITS12 and Fusarium falciforme was 86.7% - 98.8%. In the two monogenic and polygenic phylogenetic trees, SoyITS1 and SoyITS12 strain was clustered in the same evolutionary branch as F. falciforme. Strain SoyITS1 and SoyITS12 were identified as F. falciforme based on morphological characteristics, homology analysis and phylogenetic tree analysis.