Understanding of temperature effect on the occurrence of wheat Fusarium crown rot can provide the basis information for the disease development and the ecological control measures.In this study,we evaluated various temperatures on mycelial growth,macroconidia germination,wheat infection and spreading of Fusarium pseudograminearum.The results showed that four local strains of F.pseudograminearum were able to grow at 4℃-30℃,while the optimal temperature was 28℃.The macroconidia could germinate at 4℃-35℃ while 12℃-30℃ was the better temperature range for germination.The suitable temperature range was 17℃-28℃ for F.pseudograminearum infection to wheat.For extension of infectious hyphae in wheat plant,the suitable temperature range was 22℃-30℃.Furthermore,the effect of temperature on the occurrence of Fusarium crown rot by isolate was assessed by temperature cultivation test and field inoculation test at different growth stages of two wheat cultivars.The results showed that the incidence and disease index of Fusarium crown rot inoculated at sowing and standing stages were higher than that of overwintering seedling stage,which indicated that the temperature at the former stages might be more suitable than that at the latter stage for wheat infection of F.pseudograminearum and occurrence of Fusarium crown rot.

To evaluate effect of methyl jasmonate (MeJA) on the resistance to alfalfa root rot caused by Fusarium oxysporum, an [L₉ (3⁴)] orthogonal matrix experiment was performed, including alfalfa varieties, MeJA concentration and days from MeJA treatment to inoculation, and each factor had three levels to determine the incidence and related physiological parameter. These results showed that the incidence and the disease index of Gannong No.3, Longmu 803 and Zhongmu No.1 were decreased after exogenous MeJA treatment. MeJA treatment also enhanced the activity of superoxide dismutase and phenylalanine ammonia layase, but there was a slight influence on peroxidase. The weight of fresh and dry shoot had increased significantly after MeJA treatment, while the content of soluble protein of treatment groups was decreased markedly. Variance analysis and range analysis indicated that the efficiency of MeJA was affected by alfalfa varieties, MeJA concentration and days from MeJA treatment to inoculation, and MeJA concentration was the most important factor. Finally, the optimal inhibition conditions was Gannong No. 3, MeJA 0.1 mg·mL^-1, inoculation and treatment simultaneously.

The tea leaf disease, which led to a large loss of production and decrease of quality, was found in the tea region in Huishui county, Guizhou province. Some strains were isolated from the diseased samples, and the representative strains fulfilled Koch’s postulate. Then the isolates were further identified as Lasiodiplodia theobromae based on morphological characters and phylogenetic analysis with internal transcribed spacer (ITS) and elongation factor 1-α (EF-1α) regions. The results showed that the pathogen of the leaf disease occurred in Huishui county, Guizhou province was L. theobromae.

The aim of this study is to identify and characterize the species of Streptomyces causing potato scab in Yunnan province. Two hundreds Streptomyces strains were isolated from scab tubers obtained from 13 potato main planting areas in Yunnan Province in 2013, and 67 of them were pathogenic on potato in the greenhouse test. The pathogenic isolates were identified according to pathogenicity test, 16S rDNA sequence analysis, and morphological and biochemical characterization. Results revealed 10 pathogenic Streptomyces species in Yunnan Province, including S. caviscabies, S. anulatus, S. scabies, S. turgidiscabies, S. acidiscabies, S. europaeiscabiei, S. luridiscabiei, S. enissocaesilis, S. griseus and S. aureofaciens. Among them, S. enissocaesilis and S. anulatus are dominant species. S. caviscabies, S. anulatus and S. luridiscabiei are newly discovered pathogens in China. Our study suggests that the Streptomyces species causing potato scab have a rich diversity in Yunnan Province.

In order to identify the Fusariumspp.within the wiltedsoybean lines at the agricultural station of Institute of Plant Protection, Chinese Academy of Agricultural Sciences in Langfang, Hebei province, which has a high density of soybean cyst nematode Heterodera glycines in the soybean field, 335 fungal strains were obtained from 362 wilt soybean lines. 279 strains were screened by PCR using the Fusarium-universal primer pairs F1 and F2, which accounted for 83.3% of all the strains.Combining the molecular techniques including Fusarium species-specific primers and sequencing and morphology of the colony and conidia, 189 F. oxysporum strains were identified with the highest percentage at 56.4%, while 67 F. solani strains were isolated with the second highest percentage at 20.0%. Sixteen F. graminearum strains were obtained with a percentage at 4.8%. Another four Fusarium species including F. equiseti, F. proliferaum, F. avenaceum and F. chlamydosporum were also identified at low frequency with 3, 2, 1 and 1 strains, respectively. Pathogenicity assay showed that about 92.8% F. oxysporum strains had differential virulence. Theresults of this study showed that F. oxysporum was the predominant pathogen in the soybean field. Our findings not only provide scientific evidence for the control of soybean wilt disease, but also lay a foundation for the studies of the disease complex caused by H. glycines and F. oxysporum.

This study was aimed at understanding the phylogenesis of Sugarcane mosaic virus (SCMV). The complete genomes of two SCMV isolates obtained at Fuzhou, designated as FZ-C1 and FZ-C2, respectively, were cloned in this study. Based on the genome sequences of the new SCMV isolates and published 18 SCMV isolates, the genetic diversity and population structure of SCMV were analyzed using MEGA 4.1 and Simplot softwares. Results showed that the genome of FZ-C1 contains 9 570 nucleotides, while FZ-C2 contains 9 573 nucleotides. Both FZ-C1 and FZ-C2 have a single open reading frame of 9 189 nt in length and encode a polyprotein containing 3 063 amino acids. FZ-C1 and FZ-C2 shared high similarity with SCMV-A at both nucleotide and amino acid level, as well as the restriction sites. Phylogenetic analysis showed that SCMV strains could be divi-ded into three groups: SSG I, Ⅱ and Ⅲ. Strains in SSG I were mainly isolated from Zea mays, while SSG Ⅱ and SSG Ⅲ were from sugarcane, especially the SSG Ⅲ that were primarily isolated from chewing cane. Two FZ isolates were grouped into the SSG Ⅱ. Our work enriched the whole genome sequence information of SCMV and shed light on the phylogenesis of SCMV.

In order to clarify the current Fusarium species and the dominant species causing tomato Fusarium wilt in Tongshan, Qintong and Shuyang. 12 soil samples were collected from tomato rhizosphere and the pathogens were isolated. Fusarium species were identified on the basis of morphological characteristics and ITS sequences, and their pathogenicity was also tested. Three Fusarium species, namely F. oxysporum, F. solani and F. verticillioides, were classified with the numbers of 111, 32 and 7, respectively. The result of analysis of the Fusarium species distribution in different regions indicated that Fusarium oxysporum was the dominant species in Tongshan, Qintong and Shuyang with frequencies of 66%, 72% and 84%, respectively.

Huazhan is a new native restorer line bred in China and widely used in recent years. Its hybrid rice combinations showed good resistance against rice blast. In the present study, 62 blast isolates collected from South China were used for inoculating the restorer lines of Huazhan, Minghui63 and Guanghui998. The inoculation tests revealed that Huazhan was a broad resistant restorer line whose resistance spectrum (RS) was 95.2%. To identify the rice blast resistance gene(s) of Huazhan,we constructed a F₂ population derived from Lijiangxintuanheigu (LTH, as a female parent) and Huazhan (as a male parent) for genetic analysis. The blast isolate GD00-193a which had a broad virulence to rice cultivars from South China was used to inoculate all of the F₁ and 1 000 F₂ individuals of LTH/Huazhan. The genetic assay indicated that Huazhan carried a dominant resis-tance gene, since all of the F₁ plants were resistant and the segregation of resistant and susceptible progenies fitted a 3R∶1S ratio in the F₂ population. The resistance gene was mapped in the Pi2/Pi9/Pi50 region on chromosome 6 through bulked segregant analysis (BSA) and recessive class analysis (RCA) using 300 microsatellite markers equally distributed on 12 rice chromosomes. The result of further Pi2 alleles sequencing showed that Huazhan carried the Pi2 gene. The present study will provide the basis for the application of Huazhan in hybrid rice breeding and the variety distribution and rotation of its combinations.

Twig blight disease is one of the main diseases on bayberry (Myrica rubra Sieb.& Zucc). We deve-loped an effective method to detect and quantify the pathogens Pestalotiopsis versicolor and P. microspora by using conventional PCR and SYBR Green real-time PCR. A primer set, Pvm1L/Pvm1R, was designed based on a conserved sequence of the internal transcribed spacer (ITS1-5.8S rDNA-ITS2) region of the ribosomal DNA gene of P. versicolor (JN861773) and P. microspora (JN861776). The 188 bp DNA fragments were amplified from 30 isolates of P. versicolor and 30 isolates of P. microspora, and no product was amplified from isolates of 11 other fungal genera. Conventional PCR was able to detect the pathogens on symptomatic and artificially infected bayberry plants at 21 days after inoculation, and the detection limit was 0.6×10⁵ copies of the Pestalotiopsis DNA. In addition, the Pvm1L/Pvm1R primer set were successfully adapted to SYBR Green real-time PCR, which had a limit 100 times lower (0.6×10³) than that by conventional PCR and was able to detect the pathogens in symptomless, artificially inoculated, and naturally infected plants. The conventional and SYBR Green real-time PCR developed in this study were simple, fast, sensitive, and specific, and can be used to detect Pestalotiopsis spp. from infected bayberry in the field.

Fourty-three isolates of Colletotrichum spp. were isolated from diseased Hevea brasiliensis collected from 4 different counties in Hainan Province, China. The isolates were identified and the sensitivity of these isolates to carbendazim and prochloraz was determined by mycelium growth rate method. The results indicated that 23 isolates were C. gloesporioides and 20 isolates were C. acutatum. The EC₅₀ values of 43 isolates ranged from (0.332 3-7.425 6) and (0.009 1-0.113 3) mg·L^-1, respectively, with an average value of (1.714 1±1.684 7) and (0.036 8±0.023 8) mg·L^-1, respectively. The average EC₅₀ value of C. acutatum to carbendazim was significantly higher than C. gloesporioides, with an average value of (2.922 7±1.556 3) and (0.663 2±0.194 4) mg·L^-1, respectively. There were no significant difference between the average EC₅₀ value of C. acutatum and C. gloesporioides to prochloraz, with an average value of (0.038 3±0.015 2) and (0.035 5±0.020 1) mg·L^-1, respectively. There was no significant correlation between the EC₅₀ values of the tested isolates to carbendazim and prochloraz, which indicated that these two fungicides can be alternative use in disease control.

Kenaf leaf curl disease is a new disease occurred in Haikou, Hainan Province of China. The symptoms of the infected plants exhibits leaf curling upwards, vein swelling and vein dark green. PCR analysis indicates that the symptomatic plants were infected by begomoviruses and sequence analysis indicates that the isolate HN08 only contains the DNA-A component.The full length of DNA-A was 2 738 nucleotides. Multiple sequence alignment showed that the DNA-A of HN08 had more than 89.0% sequence identity with that of all other isolates of Cotton leaf curl Multan virus (CLCuMuV) deposited in GenBank, and more than 99.0% sequence identity with that of all isolates from China. The virus was also accompanied by betasatellite molecular,which was determined to be 1 346 nucleotides. Pairwise comparison indicated that the betasatellite molecular of HN08 had more than 83.0% sequence identity with that of Cotton leaf curl Multan betasatellite (CLCuMuB), and shared the highest sequence identity (99.7%) with that of isolate Fz1 from Fujian. The infectious clones of HN08 DNA-A and its betasatellite molecular, pGreenⅡ049-1.6A and pGreenⅡ049-2.0β were constructed, and were agro-inoculated into Hibiscus cannabinus plants. At 30 dpi, the new leaves of the H. cannabinus plants inoculated with the recombination of pGreenⅡ049-1.6A and pGreenⅡ049-2.0β displayed leaf curl symptoms. At 60 dpi, most of the leaves of the inoculated H. cannabinus plants showed severe leaf curl symptoms, similar to that observed in the fields. However, neither the plants inoculated with pGreenⅡ049-1.6A or pGreenⅡ049-2.0β showed visible symptoms. The results of PCR and Southern blot detection confirmed these symptoms caused by co-infection of HN08 DNA-A and its betasatellite molecular. Taken together, Kenaf leaf curl disease in Hainan province was caused by co-infection of CLCuMuV and its betasatellite (CLCuMuB). This is the first report of CLCuMuV on H. cannabinus .

Root-knot nematodes (RKN), Meloidogyne spp., are important phytopathogenic nematodes. Fosthiazate and avermectin are two chemical nematicides commonly used in controlling RKN disease. In this study, the efficiency of mixed application of Purpureocillium lilacinum and low-dosage nematicides to control RKN disease was evaluated in the laboratory and field conditions. Mycelium extension and spore germination of P. lilcacinum was not impaired after mixing with low-dosage fosthiazate (100 μg·mL^-1). Then the lethal rate of second-stage juvenile of RKN was compared after treated by P. lilacinum, fosthiazate and mixture of both compounds. The results showed that mixed-application of P. lilacinum and low-dose fosthiazate led to a significantly higher lethal rate of RKN than P. lilacinum or fosthiazate was used alone. After mixing with P. lilacinum granule, the concentrations of nematicides were reduced by 25% (avermectin) or 50% (fosthiazate) without impairing their RKN control efficiency. These results suggested that mixed-application of nematicides and the biocontrol fungus P. lilacinum could be an efficient approach to reduce the amount of chemical nematicides in controlling RKN disease. In addition, low-dose nematicides could be used to increase the stability and efficiency of P. lilacinum to control RKN. In summary, this study shows an efficient alternative strategy to control nematode with less chemical nematicides.

This article reports the new taxonomy system (2019) approved by the International Committee on Taxonomy of Viruses (ICTV) in March 2020, which fully adopted a 15-rank taxonomic structure, namely: realm, subrealm, kingdom, subkingdom, phylum, subphylum, class, subclass, order, suborder, family, subfamily, genus, subgenus, species. Viruses whose hosts are plants include plant viruses and subviral infection factors (satellite virus, satellite and viroid). There are 1 608 species of plant viruses, belonging to 2 realms, 3 kingdoms, 8 phyla, 13 classes, 16 orders, 31 families, 8 subfamilies, 132 genera and 3 subgenera. Subviral infection factors include 33 species of viroids belonging to 2 families and 8 genera, 6 species of satellite viruses belonging to 4 genera, and 142 species of satellites belonging to 2 families, 2 subfamilies and 13 genera.

To investigate the genetic diversity and phylogenic relationship of Broad bean wilt virus 2 (BBWV2) in Pseudostellaria heterophylla, RT-PCR was performed to detect 6 diseased leaf samples collected from 5 different geographical origins, and 13 clones of the coat protein (CP) genes were generated for sequence analysis. Results indicated that all sequences were 1 345 bp in length, sharing 81.0%-99.0％ identities at nucleotide level and 93.5%-99.3％ identities at the amino acid level. The nucleotide polymorphism for these sequences was up to 0.084 00. 280 polymorphic sites were identified, and most of them were geographic region-specific sites. There were 278 mutations, including 29 synonymous changes and 249 non-synonymous changes. The data showed high genetic differentiation and low gene flow among different isolates. Genetic drift could be the major cause of genetic differentiation. The phylogenetic tree revealed that all the CP genes obtained in this study could be clustered in relation to the areas where they are collected. Isolate of JS, GZ, HN and FJ belonged to subgroup I-a,whereas isolate SD belonged to subgroup II-c, indicating a long genetic distance among them. Our results suggested that BBWV2 from P. heterophylla showed a high genetic variation. Viral gene mutation could be a major evolutionary force to drive the occurrence of its genetic diversity, and geographical factor was closely related with its high nucleotide diversity.

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense race 1 (Foc1), is one of the most important diseases that causes the greatest reductions in banana yield worldwide. Secreted proteins can act as pathogenicity factors and play important roles in the Foc-banana interactions. In this study, a refined Foc1 secretome was predicted by combining several bioinformatic approaches, including SignalP, WoLF PSORT, TargetP, TMHMM and big-PI Predictor. Among the 15438 protein sequences of Foc1, a total of 988 classically secreted proteins are predicted, representing 6.40% of the total proteins. The characteristics of these proteins showed that the length of amino acids was concentrated between 101 to 500 (71.26%), the length of the signal peptides was concentrated between 17 to 20 amino acids (61.94%), signal peptide cleavage sites mainly belongs to SPase I-cleaved signal peptides (92.91%). Among the 988 classically secreted proteins, 281 carbohydrate-active enzymes were also predicted, in which glycoside hydrolases superfamily was the most numerous. In addition, 378 effector candidates were predicated with amino acid length ≤ 400 and cysteine residues ≥ 4. Quantitative PCR analysis showed that the expression of seven genes encoding the effector candidates increased significantly at transcriptional level induced by banana root extract, which further showing that these effector candidates predicted from secretomes are true effectors by experimental validation. To our best knowledge, it is the first attempt to predict Foc1 secretome and effectors on genome-wide scale, which will help to understand the mechanism of the Foc-banana interactions.

Metabolomics, genomics, transcriptomics and proteomics compose systems biology. Metabolomics is a bridge to link genes, proteins, and phenotype and thus far, it is gradually applied in the field of phytopathology. In this review, we summarized recent applications of metabolomics in different aspects of phytopathology, such as etiology, disease diagnosis, plant-microbe interaction, disease resistance of plant, noninfectious disease and modes-of-action of fungicides. It will hopefully offer reference for gaining deep insight of occurrence regularity of plant disease, immune defense of plants, and suppression mechanism of exogenous agrochemicals to pathogens through application of metabolomics. In addition, by discovering biomarkers and metabolic pathways, metabolomics will offer important reference for understanding of proteins function.

Sugarcane mosaic disease is the most serious viral disease in sugarcane growing area of China. The use of resistant varieties is the most economic and effective method to control this disease. Sugarcane streak mosaic virus (SCSMV) and Sorghum mosaic virus (SrMV) are the two predominant pathogens of mosaic disease in the cane-growing regions of China. In 2015 and 2016, double resistance to SCSMV and SrMV was identified and evaluated in 71 new elite sugarcane varieties/clones bred from China Sugarcane system by stem inoculation followed by RT-PCR detection. The results showed that out of 71 new elite sugarcane varieties/clones, 24 (33.8%) were highly to moderately resistant , and 47 (66.2%) were susceptible to highly susceptible to SCSMV; Wherease, 27 (38.03%) were highly to moderately resistant , and 44 (61.97%) were susceptible to highly susceptible to SrMV. Fifteen new elite sugarcane varieties/clones (21.13%) were highly resistant to resistant to SCSMV and SrMV. The resistant ones/varieties were Funong 30, Funong 36, Minting 01-77, Guitang 02-467, Liucheng 05-129, Yuegan 34, Yuegan 40, Yuetang 55, Yuetang 96-86, Yuetang 00-318, Ganzhe 02-70, Yunzhe 03-258, Yunzhe 04-241, Yunzhe 05-51 and Yunzhe 06-80. Of these, five new elite sugarcane varieties/clones (Yuegan 34, Yuetang 55, Yunzhe 03-258, Yunzhe 05-51, Yunzhe 06-80) were the highly resistant to SCSMV and SrMV, accounting for 7.04% of the total varieties/clones. The results in the present study have determined the resistance of 71 new elite sugarcane varieties/clones to the two main pathogens of mosaic disease, screened out 15 new elite sugarcane varieties/clones resistant to SCSMV and SrMV. These results will provide a basis for the source of resistance in production and effective control of sugarcane mosaic disease.