Alfalfa (Medicago sativa L.) is the most important pasture crop in China in terms of its planting area and status in animal husbandry. Verticillium wilt is a devastating disease worldwide, and China has listed it as an import plant quarantine object. The causal agent was previously known as Verticillium albo-atrum and renamed Verticillium alfalfae in 2011. However, on the list of quarantine diseases for the plants imported to China, the causal organism of alfalfa Verticillium wilt was still designated as V. albo-atrum. This undoubtedly brings much confusion to the quarantine work. In China, the disease was ever found in Zhangye City, Gansu Province, in 2016, and has now been widely distributed in the Hexi Corridor, the most important commercial alfalfa production area in China. It is vital to encourage relevant researchers to pay more attention to this dangerous disease so as to strengthen integrated control measures of the disease. This paper reviews research progress on Verticillium wilt of alfalfa, including the causal pathogen species, distribution, infection cycle and management measures, and suggests future research directions.

Chitin is an important component of fungal cell wall. It imparts strength and rigidity to fungal cell wall due to its crystalline nature. Chitin plays an important role in infection-related morphogenesis of phytopathogenic fungi, such as the infection structure and the infection hyphae. During the interaction between plants and plant pathogenic fungi, chitinases secreted by plants can degrade chitin to chitin oligomers. As a pathogen-associated molecular pattern (PAMP), chitin oligomer can be recognized by the membrane-located chitin receptors to stimulate plant immune responses. To successfully infect plants, plant pathogenic fungi have evolved a variety of strategies to inhibit the chitin-triggered plant immunity responses. Specifically, plant pathogenic fungi secrete many proteins such as effector proteins, polysaccharides or chitin deacetylases, chitinases and proteases to inhibit the plant defense responses. These proteins are secreted into the apoplast or inside the cell to destroy the plant immune system, which promotes the nutrient acquisition, colonization, growth, and development of the pathogenic fungi. This review summarizes the molecular mechanism of chitin recognition in plants and the main strategies to inhibit chitin-triggered plant immune responses of plant pathogenic fungi. We also discuss future research trends in this field.

To investigate the causal agent of samara brown spot occurred on Acer truncatum Bunge in Guiyang City, Guizhou Province, we collected diseased samara for pathogen isolation. YB26, a representative fungal strain causing the disease through pathogenicity test, was identified as Alternaria alternata based on combined results of morphological characteristics and multigene (rDNA-ITS, Alt a1 and GAPDH) phylogenetic analysis. Then the biological characteristics of A. alternata strain YB26 were determined by testing the mycelial growth rate under different carbon and nitrogen sources, temperatures, pH values, media and light conditions. The results showed that the suitable conditions for vegetative growth of YB26 were mannitol as carbon source, beef extract as nitrogen source, Sabouraud glucose agar (SDA) as culture medium, temperature of 28 ℃, pH value of 7, and incubation under darkness. Furthermore, the inhibitory effects of 7 fungicides against strain YB26 were tested, among which 25% pyrisoxazole had the best antifungal activity, with the EC₅₀ value of 0.8323 mg·L^-1. This is the first report of samara brown spot on A. truncatum caused by A. alternata. The results provide a basis for the diagnosis and control of the disease on A. truncatum.

Ligustrum japonicum leaf spot occurs universally in Wenhuilu campus of Yangzhou university, Yangzhou, Jiangsu, China every spring. The aim of this study was to identify the pathogen species, determine the biological characteristics, and screen out effective pesticides for the prevention and control of the disease.The multiple assays were conducted for the pathogen identification including tissue separation and single-spore purification, pathogenicity test both in vitro and vivo to fulfill Koch’s postulates, and morphological and phylogenetic analysis based on a combined ITS, GAPDH, RPB2 and TEF1 sequence dataset, the biological characterization,and the sensitivity test to the five fungicides. We obtained the purified fungal culture which was further identified as Alternaria alternata, a new pathogen causing leaf spot on L. japonicum. The effect of various carbon and nitrogen sources for growing of the representative isolate was investigated and A. alternata isolate was suitable for growing on the optimized medium supplied with sucrose, fructose, and potassium nitrate at 25 ℃, pH 9.0. In addition, 5 fungicides were assessed on the inhibitory effect against mycelial growth of A. alternata isolate in which azoxystrobin displayed the strongest inhibitory activity with EC₅₀ value of 0.080 6 μg·mL^-1, followed byprochloraz, pyraclostrobin and tebuconazole with EC₅₀ values of 2.272 2 μg·mL^-1, 3.934 9 μg·mL^-1 and 6.400 0 μg·mL^-1, respectively, while difenoconazole exhibited the least sensitivity at EC₅₀ value of 15.486 0 μg·mL^-1. These results indicated that these fungicides could be used for the prevention and control of L. japonicum leaf spot disease.

The diseased plants of Achyranthes bidentata showing typical symptoms of Fusarium wilt were collected from Jiaozuo, Henan Province, China. Tissue separation method was used to obtain potential pathogenic fungal isolates, and the pathogenicity of these isolates was determined by root-dipping inoculation method. Fusarium proliferatum was identified as the causal agent of the disease based on morphological characteristics, ITS sequence and polygenic analysis (EF1-α, Tub, RPB2 and PRO1/2). F. proliferatum isolates showed maximum radial growth at 28 ℃ and pH 7.0 on oatmeal agar medium under dark conditions. The pathogen could utilize multiple carbon and nitrogen sources, with the best carbon and nitrogen sources of sucrose and peptone, respectively. To our knowledge, this is the first report of F. proliferatum causing Fusarium wilt on A. bidentata. The results provide a scientific basis for diagnosis and control of Fusarium wilt of A. bidentata. Toxicity test of the six fungicides on F. proliferatum showed that these fungicides had certain inhibitory effects on the pathogen, and tebuconazole and fludioxonil exhibited relative higher inhibitory effects, with EC₅₀ values of 3.03 and 2.36 mg·L^-1, respectively.

Three Broussonetia papyifera samples suspected to be infected by Begomovirus, with yellow mosaic leaves, were collected from Lianping county, Heyuan city, Guangdong province. Total DNA was extracted from suspected samples individually, and was used as template for PCR detection with degenerate Begomovirus pri-mers AV₄₉₄/CoPR. The PCR detection result showed that three suspected samples were infected by Begomovirus. The full genome sequence of virus isolated from Broussonetia papyifera in Guangdong (GS-2021) was obtained by RCA amplification, followed by enzyme digestion, cloning and sequencing. GS-2021 was a bipartite virus, including DNA-A and DNA-B components. The full sequence of DNA-A (GS-2021-A) was 2 777 nt in size, and encoded seven ORFs. The full sequence of DNA-B (GS-2021-B) was 2 742 nt in size, and encoded two ORFs. GS-2021 shared the higher similarity with all isolates of clerodendrum golden mosaic China virus (ClGMCNV). GS-2021-A shared a 93.0%-93.9% identity with DNA-A of all isolates of ClGMCNV, and the highest identity (93.9%) is with the Fujian Fz7 isolate (GenBank accession number: FJ011668). GS-2021-B shared an 86.3%-89.6% identity with DNA-B of all isolates of ClGMCNV, and the highest identify (89.6%) is with the Fujian Fz7 isolate (GenBank accession number: FJ011669). GS-2021 was closely related to five isolates of ClGMCNV from Fujian, Zhejiang, Jiangsu and the United States, which belonged to the same clade. In addition, GS-2021 clustered with Fz7 isolate from Fujian in a small clade, and had the closest relationship with it. Recombination analysis showed that there was no obvious gene recombination event in GS-2021. Based on the latest demarcation threshold for Begomovirus, GS-2021 was a new strain of ClGMCNV. In this study, Begomovirus was detected on Broussonetia papyifera for the first time. The full viral genome sequence of this virus was obtained and identified as a new strain of ClGMCNV. This result shows that Broussonetia papyifera is a newly discovered natural host for Begomovirus.

Citrullus lanatus is an important horticultural plant. Viral diseases on C. lanatus have become more and more serious in recent years. In order to identify the viruses that infect watermelons, the small RNA deep sequencing was used to analyze samples with mosaic and shrinking symptoms from Taigu District, Shanxi Province. RT-PCR and bioinformatics methods were used to analyze the pathogens. The results showed that the watermelon samples exhibiting mosaic and shrinking symptoms were infected by five viruses including cucurbit aphid-borne yellows virus (CABYV), cucurbit melo cryptic virus (CmCV), watermelon virus A (WVA), watermelon crinkle leaf-associated virus 2 (WCLaV2) and cucumber green mottle mosaic virus (CGMMV). The coat protein (CP) sequences of five viruses were amplified by RT-PCR, and further analyzed by sequence identity analysis and phylogenetic analysis. It was found that the nucleotide sequence of CABYV-SXJZ (GenBank No : OP957280) obtained in this study had the highest identity with that of CABYV-Inner Mongolia (GenBank No : EU262627), reaching 100%. The nucleotide sequence of watermelon WVA isolate WVA-SXJZ (GenBank No : OP957281) has the highest identity with that of watermelon WVA isolate WVA-Huizhou (GenBank No : MK292710) and watermelon WVA isolate WVA-KF15 (GenBank No : KY363796), which are also from China, reaching 93.6% and 99.9%, respectively. The nucleotide sequence of WCLaV2 isolate WCLaV2-SXJZ (GenBank No : OP957282) has the highest identity with that of WCLaV2 Brazilian watermelon isolate Ju-01 (GenBank No : LC636075), reaching 99.6%. The nucleotide sequence of CmCV isolate CmCV-SXJZ (GenBank No : OP957283) obtained from watermelon for the first time in this study has 99.9% identity to that of Chinese melon isolate CmCV-HLJ (GenBank No : MH479773). The nucleotide sequence of CGMMV isolate CGMMV-SXJZ (GenBank No : OP957284) obtained in this study has the highest identity with CGMMV isolate GDLZ (GenBank No : MK933286), CG038 (GenBank No : MH271443), CGMMV-pXT1 (GenBank No : KY753929), eWT (GenBank No : KY753928), C284R (GenBank No : KY753927), CGMMV-XG (GenBank No : KP868654), JD2 (GenBank No : KM873785) and Anhui (GenBank No: KT236095), reaching 99.8%.

Lotus is the most important aquatic vegetable in China and has the largest cultivation area. With the expansion of cultivation and the simplification of agricultural practices, various lotus diseases have been becoming more serious, among which lotus rhizome rot disease is the most harmful and the most difficult to control. At present, there are few research reports on the pathogenesis of Fusarium spp. causing lotus rhizome rot disease around the world. From the microscopic and ultra-microscopic levels, this study revealed the changes to the rhizome and its vascular tissues during Fusarium infection. The observation of paraffin-embedded tissue sections showed that with the development of the disease, necrotic cells stained by toluidine blue appeared around the vascular bundles, and the closer to the bundles, the more numerous necrotic cells and the more densely distributed. In order to further reveal the influence of pathogen infection on vascular bundles, brightfield optical and scanning electron microscopy were used to observe the lotus fibers in the diseased lotus rhizomes. The results showed that the smooth and compact lotus fibers became rough and dispersed with the disease tending to be more severe, and a large number of galls-like protrusions and other possible metabolic attachments were attached to the surface. These changes to the vascular bundles are likely to reduce the water and nutrient transportation, and finally the aboveground parts of the plant exhibited the symptoms of water loss and wilting. The results of this study revealed the cellular biological mechanism of the disease symptom development, and provided a basis of histology for the breeding of resistant varieties in the future.

Tomato mottle mosaic virus (ToMMV), a member of the genus Tobamovirus, showed stronger pathogenicity than tobacco mosaic virus (TMV) and tomato mosaic virus (ToMV) in most solanaceae crops. To figure out the cytopathological changes of tobacco plants that were infected by ToMMV, we constructed a full-length infectious cDNA clone of ToMMV, and carried out transmission electron microscopy observation. The results showed that the rod-shaped virions of ToMMV were 220-310 nm in length and 16-18 nm in diameter. ToMMV virions were also observed in the seeds of ToMMV-infected Nicotiana tabacum var. Xanthi nc. ToMMV virions were dispersed or angularly-layered in cytoplasm or vacuoles. Multivesicular bodies, small vesicles, myeloid bodies, mitochondrial cristae were observed to be reduced or disappeared in both N. tabacum var. Xanthi nc and N. rustica infected with ToMMV. In addition, broken chloroplast membranes and large amount of small peripheral vesicles protruding into the disintegrated chloroplasts were observed in the infected N. tabacum var. Xanthi nc showing mosaic and distortion symptoms, while large amount of small vesicles were observed in the cells of infected N. tabacum var. Xanthi nc showing leaf narrowing. However, chloroplasts changes were less frequent in N. rustica with systemic necrosis symptoms. In this study, the construction of ToMMV infectious clone and the observation of cytopathological changes in tobacco plants infected with ToMMV, provided important bases for the further study of the pathogenesis of ToMMV and its interaction with the host.

Lasiodiplodia theobromae is an important plant pathogenic fungus, infecting more than 500 species of woody plants and causing serious damages worldwide. The secreted proteins of pathogenic fungi play important roles in pathogen invasion, expansion, and colonization in plants. Although there are more reports on the involvement of classical secreted proteins in fungal pathogenicity, the roles of non-classical secreted proteins in the pathogenesis of plant pathogenic fungi have rarely been investigated. In this study, 238 candidate non-classical secreted protein-coding genes were obtained by bioinformatic prediction based on the whole genome sequence of L. theobromae. Gene functional prediction and GO enrichment analysis showed that these genes are enriched in the carbon-sulfur lyase activity pathway. The annotation results based on PHI-base showed that 15 non-classical protein-coding genes might be related to the pathogenicity of L. theobromae. Predication of subcellular location using ApoplastP showed that 4 of them were located in plant apoplast and 11 were located in plant proplastids. Reverse transcription quantitative PCR (RT-qPCR) analysis results further verified that the transcriptional expression levels of the above candidate non-classical secreted protein-coding genes were significantly changed after treatment with grapevine branch tissues, indicating that these non-classical secreted proteins may play important roles in grapevine-L. theobromae interaction. The results lay a foundation for further understanding of the pathogenic mechanism of non-classical secreted proteins of L. theobromae.

The potato early blight caused by Alternaria solani is an important disease in potato production, which seriously affects the yield and quality of potatoes. To reveal the interaction mechanism between A. solani and its host plant potato, we screened the effector candidates produced by A. solani during its interaction with potato plant using RNA transcriptome sequencing technology and biological software (signalp-4.1, tmhmm-2.0c, phobius101 and ProtComp v3) combined with characteristics analysis of effector proteins. As a result, 137 differentially expressed candidate proteins were obtained, and four (Gene03396, Gene06670, Gene02858 and Gene06508)of them were selected for further analysis. Based on the result of RNA-seq analysis, Gene03396, Gene06670 and Gene02858 had an up-regulated expression pattern at three time points (3, 4 and 5 dpi) compared with that at 0 dpi, whereas Gene06508 had a downregulated expression pattern. The four proteins do not have a common motif according to the MEME analysis result. Transient overexpression of the target effector candidate genes in tobacco showed that Gene03396 and Gene02858 directly induced tobacco cell necrosis, and Gene06670 inhibited programmed cell death (PCD) induced by BCL2-associated X, indicating that effector candidates function by stimulating plant immunity or inhibiting host defense response. The subcellular localization results revealed that Gene03396 was located on the cell membrane, while Gene06670 and Gene02858 may be located in the intercellular space. These results provide a basis for further identifying the effector proteins of A. solani and revealing the underlying pathogenic mechanism of the pathogen.

Poplar leaf rust is serious harm to the tree health and planting resistance cultivar is an effective way to control the disease. The breakdown of resistance owing to the variation of pathogen, it is urgent for exploring new resistance resources. Plant nonhost resistance, characterized by broad-spectrum and durability, provides a new resolution for resistance breeding. In the present study, the histology observation and the expression pattern of defense-related genes of wheat leaves inoculated with Melampsora larici-populina (Mlp), the casual agent of popular leaf rust, were analyzed. The results demonstrated that although Mlp urediniospores normally germinated on wheat leaves, only 3.7% recognized the stomata, and a very few of them were able to develop sub-stomatal vesicle-like (SSVL) structure and infection hypha. The immediately induction of H₂O₂ and callose at the infection site arrested the further infection of the rust fungi. In addition, no cell death was observed, suggested that the defense reaction of wheat against Mlp belongs to type I nonhost resistance. Two genes involved in jasmonic acid synthesis, LOX1 and AOS1, as well as PR1a, the downstream pathogenesis related gene of JA pathway, were all induced by Mlp infection, highlighted an important role of JA pathway in wheat nonhost resistance to Mlp. This study provided groundwork for further elucidation of the molecular mechanism of wheat nonhost resis-tance to poplar leaf rust.

Barley spot blotch, caused by the facultative B. sorokiniana, is an important foliar disease on barley, being widely prevalent in most barley-growing regions in the world. It is most destructive especially in the regions with warm and moist climates, consequently bringing about serious yield losses.Presently, spot blotch is the first important fungal epidemic disease in the spring barley-growing regions in northeastern China.The disease usually occurs in mid- and late-growth stages of barley. Growing resistant varietiesis, therefore,the most cost-effective measure for the disease control. In this study, two highly virulent dominant B.sorokiniana isolates Z12028 and Z15525 derived from northeastern China were selected to identify spot blotch resistance in barley germplasm accessions at the seedling and adult plant stages. Only one accession 2013F₆1903 was found to be highly resistant to Z12028 at the seedling stage, and no immune one accession to B. sorokiniana was detected. Nine accessions, such as ZDM00009,ZDM00013,ZDM00094,ZDM08888,ZDM01414,ND14049,ND B112,Newdale, and kenpimai 9 among the tested germplasm accessions, were found to be of allstage resistance to the both highly virulent isolates; fourteen accessions (4.3%)like ZDM00074,Bowman and Stander were resistant only at the seedling stage but susceptible at the adult plant stage, and another 72 accessions(28.3%) of adult plant resistance to spot blotch. Barley accessions of adult plant resistance accounted for 28.1% and 29.5% to Z12028 and Z15525, respectively. As a result, the percentage of adult plant resistant accessions to spot blotch was significantly higher than that of those with all stage resistance. The results of this study provided valuable resistant resources for exploiting new spot blotch resistance genes.

The root rot caused by Fusarium and Ilyonectria is the most serious disease in American ginseng. The prevention of this disease mainly relies on the utilization of fungicides. However, it is unknown whether it could be controlled by calcium fertilizer. In order to reduce the use of pesticides and find possible physiological and ecological mechanisms of calcium in root rot disease control, a pot experiment was conducted to investigate the effects of calcium application and inoculation. During the cultivation of ginseng, different amounts of calcium oxide (0、0.5、1.5、4.5 g·kg^-1 ) was applied to the soil. The root biomass, disease incidence, root nutrient content, soil physicochemical properties and soil microbial community were measured. The results showed that low calcium additions increased root rot disease index, however, high calcium additions decreased root rot disease index. Compared to the control, adding 4.5 g·kg^-1 calcium oxide decreased root rot disease index of I. mors-panacis by 87.69% (P < 0.05), meanwhile, the root rot disease index of F. solani was reduced by 66.67% (P>0.05). The calcium content in American ginseng roots from the two inoculation groups were increased by 101.28% and 61.50% (P<0.05), respectively. Nitrogen and phosphorus content in the roots were positively correlated with the root rot disease index of F. solani. On the other hand, the structure and composition of soil microbial communities inoculated with two pathogens differed significantly. The calcium treatment mainly affected the diversity and composition of fungal community, while having little effect on the bacterial commun-ity. Additionally, treatment with 4.5 g·kg^-1 calcium oxide inhibited the relative abundance of Didymella and Phoma. Overall, the potential mechanism for the reduction of root rot disease in American ginseng by more than 65% through the application of high-dose calcium is related to increased calcium content in roots, reduced nitrogen and phosphorus content in roots, and decreased the relative abundance of potential pathogens in soil. This study provides a theoretical basis for reducing root rot disease of American ginseng through rational application of calcium fertilizer.

In order to obtain high-quality and sufficient protoplasts of Botrytis cinerea that can be used for genetic transformation, effects of multiple parameters including mycelial age, combinations of lytic enzymes, types of osmotic stabilizers, enzymatic hydrolysis temperature, and time of enzyme digestion on protoplasts preparation were studied. The optimal lytic enzyme was determined to be the combination of driselase, snailase, and lysing enzyme at an active ingredient of 1%, 0.1% and 1%, respectively, and the mycelial age, composition and concentration of osmotic stabilizer, enzyme digestion temperature, and enzyme digestion time were as follows: mycelia of JA-6 was cultivated on PDA at 25 °C for 36 h, osmotic stabilizer contained 0.6 mol·L^-1 KCl and 50 mmol·L^-1 CaCl₂, and enzyme digestion time was 3 h at 120 r·min^-1 at 28 °C. Enzymatic hydrolysis of 5 g·mL^-1 of B. cinerea mycelium can yield 1.06×10⁷ protoplasts·mL^-1 under above optimal protoplast preparation conditions. No significant differences of the colony morphology, growth rate, conidial production and pathogenicity were observed between the regenerated strain and the wild-type strain. The GFP (green fluorescent protein) gene was subsequently transformed into B. cinerea JA-6 by PEG mediated transformation. The fluorescence signal of the transformants can be stably inherited. The established protoplast preparation method in the present research would meet the requirements of genetic transformation of B. cinerea for further study.

In the researches of chemical control of plant diseases, the mechanism of action of fungicides and pathogen resistance to fungicides are the focus of attention, while the mechanisms of how pathogenic bacteria response to mitigate chemical stress is often ignored. The transcriptome sequencing technology was used to study the stress response mechanism of Fusarium graminearum to succinate dehydrogenase inhibitor (SDHIs) fungicides in this study. The results showed that 1 180 up-regulated and 937 down-regulated differentially expressed genes were identified in the pathogen treated with pydiflumetofen and benzovindiflupyr compared to the control. Complex II on mitochondrial electron transfer chain is the target of SDHIs fungicides. Therefore, the genes rela-ted to mitochondrial electron transfer chain were focused in this study. The results showed that F. graminearum responded to the stress of SDHIs fungicides by upregulating the expression of genes such as Succinate dehydrogenase, Ubiquinol-cytochrome C reductase, Fumarylacetoacetate hydrolase (FAH), ABC and MFS transpor-ters, and downregulating the expression of genes in the SWI / SNF complex and other genes. FgFAH gene was induced to express after being treated with SDHIs fungicides. The sensitivity of FgFAH gene-knockout mutant to SDHIs fungicide was increased compared to wild type, indicating that this gene may mediated the stress response of F. graminearum to SDHIs fungicide. The results of this study will provide a research basis for studying stress response mechanism of pathogen to chemical agents and research ideas for developing sensitizers of fungicides in the future.

Virus disease is a main constraint that influences sweet potato yield and quality. The most important viruses for sweet potato are the sweet potato chlorotic stunt virus (SPCSV) of the genus Crinivirus and sweet potato feathery mottle virus (SPFMV) of the genus Potyvirus. SPCSV-infected sweet potato storage roots incline to develop severe viral disease at the seedling stage. However, the effect of whitefly (Bemisia tabaci) in sweet potato fields on the proportion of SPCSV-viruliferous storage roots and viral disease occurrence remains largely unknown. Here, we report that the amount of whitefly and the rate of SPCSV-viruliferous whiteflies in sweet potato fields were closely related to the viruliferous rate of storage roots. When there was a high number of viruliferous whiteflies in sweet potato fields, a high rate of viruliferous storage roots were triggered, even though virus-free sweet potato cuttings that would not induce severe symptoms in above ground plants had been planted. The SPCSV infection rate and double infection of storage roots with SPCSV and SPFMV presented significant positive correlations with the virus-like symptom rate in sprouts generated from the storage roots. The symptom rate in sprouts can be predicted by the viruliferous rate of storage roots.

In order to clarify the variation of virus content of wheat yellow mosaic virus (WYMV) in various disease grade and tissue parts, wheat samples with typical incidence levels of 0, 1, 2 and 3 were collected from fields with uniform incidence of wheat yellow mosaic disease. Healthy wheat samples from virus-free fields were used as blank control. The absolute quantification of the content of wheat yellow mosaic virus in roots, stems and leaves was carried out by real-time fluorescent quantitative PCR (RT-qPCR). The results showed that the content of WYMV in wheat roots was significantly higher than that in leaves (P<0.05), and the virus content in wheat roots of grade 0 was 13.97 times higher than that in leaves. In wheat tissues of different disease grade, the virus content in roots, stems and leaves increased significantly with the aggravation of disease grade (P<0.05). The virus content in roots increased rapidly and then slowed down. From grade 0 to grade 1, the virus content in roots increased by 3.95×10⁶ copies·μL^-1L. However, from grade 1 to grade 3, the virus increase was only 1.45×10⁶copies·μL^-1. The virus content in stems and leaves showed a trend of uniform increase, and there was a strong positive correlation between the virus content in stems and the disease grade (R²=0.996 7). This study confirmed that the root is the key tissue site of WYMV virus infection in wheat. At the same time, it was found that the content of WYMV in the roots of diseased grade 0 wheat was much higher than that in the control group. The content of WYMV in the stem correlates closely with viral symptoms. The higher the content of stem virus, the more obvious the symptom of wheat.

Pepper (Capsicum annuum L.), belonging to the Solanaceae family, is an economically important vegetable crop in China. In April 2021, severe downy mildew-like symptoms were observed on pepper in Ningxiang County, Changsha City, Hunan Province. The diseased pepper plants exhibited large, interveinal chlorotic lesions on the adaxial surface of the leaves, which coalesced and turned necrotic as disease progressed. Meanwhile, white to gray mycelia could be seen on the abaxial side. Based on morphological characteristics, rDNA-ITS and cox2 sequence analysis, and the result of pathogenicity test, the pathogen was identified as Peronospora capsici. This is the first report of downy mildew caused by P. capsici on pepper in Hunan Province, China, and the sequence information of P. capsici was for the first time deposited in the NCBI nucleotide database.

In May of 2021, a leaf spot disease of the herbal medicine Dysosma versipellis was observed,and it occured seriously in Shiyan of Hubei Province. Diseased leaves of D. versipellis were collected, pathogen was isolated by tissue cultural-method, and its pathogenicity was confirmed according to the Koch's postulates. Based on the morphological characteristics and phylogenetic analysis by combination of ITS region and EF1-α gene sequences, pathogen was identified as Alternaria alternata. This is the first report leaf spot of Dysosma versipellis caused by A. alternata in China.

In order to improve the efficiency and reliability of bacterial wilt resistance screening in peanut, a novel water culture inoculation system was developed. Resistant peanut variety ‘Zhonghua21’ and susceptible ‘Zhonghua12’ were inoculated with mixed suspension of three Ralstonia solanacearum isolates under (28 ± 2) ℃, and 16 h light/8 h dark conditions. The minimum concentration for distinguishing the resistant and susceptible peanut lines was 1×10⁷ CFU·mL^-1. The optimal time for scoring the resistance was 12 d after inoculation. 36 peanut accessions were inoculated by the mixed bacterial suspension in water culture, in which 25 ones were resistant and 11 ones were susceptible. The same set of peanut accessions was also tested for their resistance to bacterial wilt in natural disease nursery, from which 27 ones were resistant and nine were susceptible. The consistency of these accessions for resistance to bacterial wilt both in water culture and in natural disease nursery was more than 80%. Therefore, the established method was quick, simple and high throughput for identifying resistance to bacterial wilt in peanut.

Small RNA (sRNA) triggered RNA silencing plays significant roles in viral resistance response by plants. Analysis of virus-derived sRNA profiles in plants is an efficient method for virus identification and de novo assembly of viral genomes.In this study,suspected virus-infected Hibiscus tiliaceus samples collected from Nanning were used for sRNA library construction and subsequent deep sequencing.After the assembly of total sRNAs,H. tiliaceus leaves were found to be infected by hibiscus chlorotic mottle virus (HCMV).The library gene-rated about 11.77 million sRNA reads,of which 15 093 can be mapped onto viral genomes.Using de novo assembly and GenBank Virus RefSeq database blast,a candidate virus covers 18.8% of the full length genome nucleotide sequence of a badnavirus, which has the highest similarity to hibiscus bacilliform virus isolate GD-1 (HBV-GD1).To confirm the existence of HCMV in the samples,a fragment of about 1 400 nucleotides encoding Reverse transcriptase /RNase H was obtained by PCR,and confirmed by Sanger sequencing.This is the first report about using sRNA deep sequencing technology to identify the Hibiscus tiliaceus infecting virus, and this provides important information for further study on the molecular characteristics of HCMV and virus-host interactions.

During a survey in 2022, cucumber displayed yellowing and chlorotic symptoms on leaves in Qingzhou and Shouguang, Shandong Province. In order to investigate the virus species, eight samples were collec-ted, and total RNA was extracted from each sample. Three high quality RNA samples were mixed together for the next-generation sequencing (NGS). The NGS clean data were assembled into large contigs and then compared with the GenBank Virus RefSeq database using BLASTn software. The BLAST results were verified with reverse transcription-polymerase chain reaction (RT-PCR), confirming that the cucumber samples were infected by five species of virus, including watermelon silver mottle virus, cucumber mosaic virus, cucurbit aphid-borne yellows virus, zucchini yellow mosaic virus and watermelon mosaic virus. After cloning the full-length of S RNA (GenBank No. OQ184866), we found that the N gene of WSMoV was 828 nt in length,encoding 275 aa, sharing 92%-98% sequence identity with other WSMoV isolates. Further phylogenetic analysis showed that the N gene formed an independent cluster and was mostly related to the cucumber isolate. This is the first report that watermelon silver mottle virus infects cucumber in Shangdong Province.

To clarify the taxonomic status of the phytoplasma causing willow witches’-broom in Gansu Pro-vince, this study used nested PCR technique to clone the 16S rDNA gene using total DNA collected from different regions and species of willow witches’-broom samples as templates, and nine 1 250 bp target fragments were obtained using P1/P7 and R16F2n/R16R2; the sequences of the above genes were compared by homology, The results showed that the 16S rDNA gene of willow witches’-broom phytoplasma strain had the highest homology with Willow proliferation phytoplasma (Willow proliferation) in Inner Mongolia, both above 99.1%; the phylogenetic tree was constructed and found that the 16S rDNA gene of willow witches’-broom clustered with members of 16SrVI-A subgroup. The phylogenetic tree was constructed, and the 16S rDNA gene of willow witches’-broom clustered with members of the 16SrVI-A subgroup; and the virtual RFLP analysis reported that the highest sequence similarity with the one obtained in this study was the reference pattern of the 16SrVI-A subgroup, with a similarity coefficient around 0.98, so the willow witches’-broom phytoplasma in Gansu Province could be classified into the 16SrVI-A subgroup. Meanwhile, the phytoplasma resources were preserved by grafting and identified as vector insects based on amplification of the 16S rDNA gene in the willow shoulder reticulata.

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.

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.

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.

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.

To understand the occurrence and genetic evolution of sweet potato chorotic fleck virus (SPCFV) in Shandong province, China, 131 sweet potato samples were collected for the detection of SPCFV in 2019 and 2020, and two complete sets of genome sequences were amplified and analyzed. The SPCFV detection rate in 2019 and 2020 was 7.1% and 5.6%, respectively. All positive samples were co-infected with SPCFV and other sweet potato viruses. The two complete sets of genome sequences (CFV-SD1, CFV-SD2) were obtained by RACE and RT-PCR, with a total length of 9 105 bp and a nucleotide similarity with the reported isolates was 72.9% to 89.5%. Phylogenetic analysis of genome sequences revealed that all SPCFV isolates clustered into two groups based on the CP genes of six Shandong isolates and that all Shandong isolates belong to the Asian group (Asian isolates 1). Amino acid preference analysis showed that the first 35 amino acids in the N-terminal region of the SPCFV CP protein exhibited variation. This study indicated that Shandong province has become a frequent occurrence area of SPCFV and the virus population was diverse. The results provide a theoretical basis for the effective prevention and control of SPCFV.

Two species of spiral nematode were intercepted from the rhizosphere of Acer palmatum Thumb. imported from the Netherlands, which were identified as Helicotylenchus microcephalus Sher and Rotylenchus robustus (Thorne) Loof & Oostenbrink, respectively, based on both morphological and molecular characteristics. There are no reports on these two species in the Netherlands. It was also the first record on the damage of two nematodes on A. palmatum. The 50:1 population proportion of two nematodes indicated that H. microcephalus was the predominant ones. Finally, the obviously pathological symptoms were observed on the roots of A. palmatum.

Eight populations of Ditylenchus destructor were isolated from three tuber crops (Solanum tuberosum, Dioscorea esculenta and Dioscorea polystachya) in Shanxi Province. Morphology characteristics of D. destructor populations were observed and measured, and then the morphological data were analyzed by SPSS and PCA software. Nematode universal primers were used for PCR amplification and sequencing of rDNA-ITS. Similarity distance and sequence alignment were analyzed by Geneious Prime 2019.2.3 and DNAMAN 9.0 software, respectively. Analysis of variance of molecular variance (AMOVA) was constructed by Arlequin 3.5 software. The phylogenetic tree and haplotype network diagram were constructed by MrBayes 3.2.7 and PopART 4.8.4 software, respectively. The results showed that seven populations of D. destructor (YH277, YH279, tg38, XF01, CZ15, TY15 and tg49) are belong to type A, and their hosts are D. esculenta, S. tuberosum, and D. polystachya. Nevertheless, the PX04 population is belongs to type C and the host is S. tuberosum. The morphology of PX04 population is significantly different from the other seven populations, with the PX04 population having a slightly pointed tail. PCA analysis result also suggested that PX04 population was obviously separated from the other seven populations. The result of haplotype network structure was constructed using 77 ITS sequences of D. destructor isolated from D. esculenta, D. polystachya and S. tuberosum. The results showed that two shared haplotypes and 26 unique haplotypes. Among them, the frequency of the H1 was the highest among the three tuber crops, which suggests that it might be an ancestral haplotype; Among 26 unique haplotypes, the highest number of exclusive haplotypes and the most abundant haplotype and nucleotide diversities were found in the population of D. destructor parasitized the S. tuberosum, with a haplotype diversity index (Hd) of 0.841 and the inter-population nucleotide diversity index (Pi) of 0.005 02. The result of AMOVA analysis showed that the genetic differences of the D. destructor in Shanxi Province were mainly from inter-populations, and there was a sizeable genetic differentiation between type A and C of D. destructor.

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.

Caspase is known to be involved in modulating apoptosis in mammals,controlling the occurrence and development of various diseases. In present study, the null mutant ΔFgCas4 and complemented strain ΔFgCas4-C of the caspase gene FgCas4 were obtained by gene disruption and complementation respectively in Fusarium graminearum. We observed that the FgCas4 deletion mutant (ΔFgCas4) did not affect the growth rate, colony morphology, conidiation, virulence and DON production. However, the deletion mutant ΔFgCas4 exhibited more hyphal branching and percentage of conidia with 3 septa increased by 8.7% compared to wild type PH-1 and complemented strain ΔFgCas4-C. External environmental stress assays showed that the gene disrupt mutant ΔFgCas4 became more sensitive to tested fungicides and metal ions. In addition, the lack of FgCas4 led to dramatically increased lipid droplet biosynthesis as well as increased resistance to osmotic stress agents. Subcellular localization showed that the caspase FgCas4 localized in vacuoles. On the other, the loss of FgCas4 resulted in earlier process of autophagy. Taken together, our study provides evidences that the caspase FgCas4 of Fusarium graminearum plays important roles in asexual reproduction, various environmental stress responses and auto-phagy regulation.

The bacterial wilt caused by Ralstonia solanacearum has brought a serious threat to tomato production. Coronatine (COR), structurally similar to JA-Ile (JA-isoleucine), is a compound produced by Pseudomonas syringae. In this study, we observed that pre-treatment of tomato seedlings with COR alleviated the symptoms caused by R. solanacearum. To investigate how COR affects tomato resistance to R. solanacearum, transcriptome sequencing of tomato seedlings inoculated with the pathogen 24 h after COR treatment was carried out. Analysis of RNA-seq data showed that COR treatment induced a total of 2122 differentially expressed genes (DEGs), including 998 up-regulated genes and 1124 down-regulated genes. DEGs annotation and pathway enrichment were conducted using GO database and KEGG database, and the results showed that COR affected the expression of genes related to plant-pathogen interaction pathway and plant hormone signaling pathways. Meanwhile, COR induced the up-regulation of genes involved in the jasmonic acid synthesis pathway and inhibited the expression of photosynthesis-related genes. Our results provide a theoretical basis for revealing the role of COR in plant-microbe interaction.

Oidium heveae is an incompatible pathogen of Arabidopsis Col-0, and triggers disease resistance in Arabidopsis in an EDS1 (ENHANCED DISEASE SUSCEPTIBILITY 1) and PAD4 (PHYTOALEXIN DEFICIENT 4) dependent manner, suggesting that TIR-NB-LRR (TOLL INTERLEUKIN 1 RECEPTOR, NUCLEOTIDE-BINDING, LEUCINE-RICH REPEAT) genes may involve in the disease resistance against O. heveae. In this study, the differentially expressed TIR-NB-LRR genes targeting O. heveae were screened, and the expression of WRR4C (WHITE RUST RESISTANCE 4C) gene was found to up-regulated induced by O. heveae. Through inoculation assay, O. heveae was observed to develop dense hyphal network and a few conidia in two wrr4c single mutants, and triggered significantly decreased defense responses including cell death, callose deposition and PR1 (Pathogenesis Related 1) gene expression, indicating that WRR4C positively regulated the disease resistance of Arabidopsis against the powdery mildew of Hevea brasiliensis. However, WRR4C gene did not participate in the cell pre-penetration resistance to O. heveae, and the expression of WRR4C reached to the highest level at 48 hours post inoculation, suggesting that WRR4C genes was mainly involved in the cell post-penetration resistance of Arabidopsis to O. heveae. In addition, we found WRR4C also positively regulated the disease resistance against Erysiphe polygoni in Arabidopsis.

To master pathogenic characteristics of Pyricularia oryzae is the premise and foundation of screening germplasm, breeding resistance, and deploying rice varieties resistant to blast. In this study, total 166 isolates of rice blast fungi were collected from Japonica rice planting area in Jilin Province, northeast China, and were inoculated to 7 Chinese differential varieties (CDVs) and monogenetic differential varieties (MDVs) which harbored 23 resistance genes in greenhouse condition, then pathogenicity was clarified in accordance with compatibility reaction. Those isolates were categorized into 7 groups and 44 races according to the CDVs' phenotypes, in which the dominant Chinese race group was ZA at the frequency of 45.18%, and the dominant races were ZA17(19.28%) and ZG1(9.64%), respectively. No dominant race types with U-i-k-z-ta criteria were demonstrated according to the MDVs' phenotype data, but the sub-groups data were prominent, and the higher sub-groups with frequency were U73(47.0%), i5(31.9%), and i7(31.9%), respectively. Based on the MDVs data, the higher frequency of the avirulence genes, Avr-Pi12(74.69%), Avr-Pi9(72.28%), Avr-Pi19(68.67%), and Avr-Pi20(68.07%), which indicate that broad spectrum genes were Pi12(t), Pi9(t), Pi19(t), Pi20(t), respectively. The information of the types of dominant avirulence genes not only presents the pathogenicity of blast fungus, but also reflects the types of genes with varieties of broad spectrum resistance in MDVs, so it would be benefit for breeding resistant to rice blast.

In 2021 and 2022, the resistance level of 16 major rice varieties to Fusarium head blight (FHB) in Jiangsu Province was evaluated under artificial and natural infection conditions. Meanwhile, the accumulation level of trichothecenes, including nivalenol, deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, and fusarenone X, was also detected in these rice varieties. The results showed that 9 rice varieties, including 4 japonica varieties and 5 indica varieties, were moderately resistant to FHB under artificial infection conditions, and the resistance of different rice varieties to FHB in 2021 was consistent with that in 2022, with indica varieties showing significantly higher resistance to FHB than japonica varieties (P<0.05). However, under natural infection in the field, the resistance of different rice varieties to FHB was quite different between 2021 and 2022, and the result was also different from that obtained under artificial infection conditions. In addition, the resistance of indica rice varieties to FHB was also higher than that of japonica varieties. Moreover, the accumulation level of trichothecenes was different among various rice varieties, and there was a significantly positive correlation between trichothecene content and disease index (P<0.01). Our results reveal the resistance of main rice varieties to FHB in Jiangsu Province, making the basis for evaluation of resistance level of rice varieties against FHB and breeding and deployment of FHB-resistant rice varieties.

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.

Microbial communities within plant root systems play significant roles in host growth and development, nutrient absorption, and disease resistance. To investigate the correlation between changes in the wheat root microbiome and the occurrence of wheat yellow mosaic, and consequently seek biological control methods for wheat yellow mosaic, this study collected wheat root samples that are healthy (H), moderately infected (M), and severely infected (S). The bacterial community structures within the wheat roots under varying degrees of infection and their environmental driving mechanisms were studied. Results revealed that as the degree of infection increased, the richness of bacterial communities within the wheat roots showed a declining trend. Bacterial community structures significantly differentiated among varying degrees of infection and were related to changes in the nutrient content of rhizosphere soil. Specifically, the genera Curtobacterium, Rhizobium, Mesorhizobium, Sphingomonas, and Luteibacter were enriched in infected wheat roots, and their relative abundance was positively correlated with the nitrate nitrogen (NO^-₃-N), available phosphorus (AP), organic carbon (SOC), total phosphorus (TP), total potassium (TK), and plant carbon (PC) content in the rhizosphere soil, but negatively correlated with ammonium nitrogen (NH⁺₄-N) and magnesium (Mg) content. The genus Pantoea was enriched in healthy wheat roots, and its relative abundance was positively correlated with plant nitrogen (PN) content. These findings indicate that changes in the bacterial community structure within wheat roots are related to the occurrence of wheat yellow mosaic and the increase in nutrient content in the rhizosphere soil.