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.

To assess the resistance level of the wheat germplasms to stripe rust and the distribution of stripe rust resistance gene(s) in Gansu province, 62 wheat varieties (lines) were collected and evaluated with stripe rust. In the greenhouse tests, seedlings of the germplasms were challenged with the predominant Puccinia striiformis f. sp. tritici (Pst) races CYR31, CYR32, CYR33, and CYR34, respectively. In the field tests, the germplasms were evaluated for stripe rust resistance at the adult stage in three natural infection disease nurseries. Also, the stripe rust resistance gene(s) were detected by gene chip based on close linkage or functional markers. The results of seedling evaluation showed that among the 62 wheat germplasms, 61 (98.4%), 53 (85.5%), 45 (72.6%), and 32 (51.6%) showed resistance to Pst races CYR31, CYR32, CYR33, and CYR34, respectively. Combined with the results of disease resistance identification at the adult plant stage, 20 (32.87%) germplasms had all stages resistance (ASR), 21 (33.87%) showed adult plant resistance (APR), and 21 (33.87%) were susceptibility. Molecular detection results indicated that 5, 14, 4, 24, 6, 16, 4, 9, 4, 3, 42, and 12 germplasms carry the resistance genes Yr17, Yr26, Yr29, Yr30, YrAK58, Yr75, Yr78, Yr80, Yr82, YrSP, QYrqin.nwafu-2BL and QYr.nwafu-4BL, respectively. And 18, 14, 9, 2, and 1 germplasms carrying two to six stripe rust resistance genes simultaneously, accounting for 71.0%. This study lay a scientific basis for resistance breeding and the rational deployment of disease resistant varieties in Gansu Province.

The anthracnose of Camellia oleifera caused by Colletotrichum siamense seriously restricts the development of Camellia industry in Yunnan Province. In order to understand the response of plant during infection, an interaction system between C. siamense and Arabidopsis thaliana was established. In this study, at 3 day post inoculation (dpi), 5 dpi, and 7 dpi, the transcriptome was sequenced to generate a total of 9644, 11583 and 12050 differentially expressed genes (DGEs), respectively. All the altered genes with up- and down expression level were classified according to their molecular function. Majority of the genes related to jasmonic acid (JA) / ethylene (ET) signal pathway and some involved in salicylic acid (SA) pathway were up-regulated and the transcription factor family related to Arabidopsis hormone signal transduction pathway and resistance response were also induced to express, while the genes related to cellulose synthase were mainly down-regulated, moreover, the altered genes above were also validated through qRT-PCR. KEGG function annotation results of DGEs showed that up-regulated genes were mainly annotated into energy metabolism, signal transduction and environmental adaptation pathways, whereas down-regulated genes were mainly annotated into carbohydrate metabolism, lipid metabolism and translation pathways. The results of KEGG functional enrichment showed that the up-regulated genes were mainly enriched in plant pathogen interactions, oxidative phosphorylation and MAPK signaling pathway, and the down-regulated genes were mainly enriched in cutin, suberine and wax biosynthesis, DNA replication and pentose and glucuronate interconversions. In summary, our study explored the defense mechanism of A. thaliana in response to C. siamense infection through activation of the downstream resistance genes regulating JA/ET and SA signal transduction pathways, which provided a theoretical basis for subsequent resistance breeding and green prevention and control of anthracnose in C. oleifera.

The role of miRNAs in regulating resistance to Sclerotinia sclerotiorum in oilseed rape (Brassica napus) is largely unknown. In this study, functions and mechanisms of miR6030 in resistance to S. sclerotiorum were analyzed. The results showed that miR6030 was expressed differentially in various tissues, higher in roots and stems while lowest in flowers. Silencing and transient over-expression of miR6030 in oilseed rape plants demonstrated that miR6030 negatively regulates resistance to S. sclerotiorum. The degradome analysis and GUS staining assay revealed that miR6030 targets BnaCnng64090D and BnaA09g10520D, which encode CC-NBS-LRR (CNL) proteins and positively regulate resistance to S. sclerotiorum. All the results indicated that miR6030 negatively regulates resistance to S. sclerotiorum via cleaving transcripts of the two CNL protein-encoding genes BnaCnng64090D and BnaA09g10520D. This study provides some insights into functions of miR6030 and molecular mechanisms underlying the resistance to S. sclerotiorum and new strategy for molecular breeding for the resistance of Brassica napus to S. sclerotiorum.

In order to analyze the resistant genotypes and field application of different cultivars, tomato yellow leaf curl virus (TYLCV) resistance genes Ty-1,Ty-2, Ty-3 and Ty-3a were tested from 43 tomato cultivars through molecular marker technology. At the same time, field natural identification methods were used to verify the resistance level of different genotypes. Results based on the molecular detection showed that 31 tested cultivars contained Ty genes, which accounted for 72.09% of the total varieties; During detection of the resistant genes, Ty-1 has the highest detection rate of 65.12%, which showed that Ty-1 was the most widely used gene for tomato virus disease resistance breeding. 10 resistance genotypes were detected in all tested cultivars which contain 1-3 resistance genes respectively. The resistance performance from high to low was: Ty-1/ty-1+Ty-2/ty-2+Ty-3a/ty-3、Ty-1/Ty-1+Ty-2/ty-2+Ty-3a/ty-3a、Ty-1/Ty-1、Ty-1/ty-1+Ty-3/ty-3、 Ty-1/ty-1+Ty-3a/ty-3a、Ty-1/Ty-1+Ty-3a/ty-3a、Ty-3a/ty-3a、Ty-1/ty-1+Ty-2/ty-2、Ty-1/ty-1 and Ty-2/ty-2, respectively. Resistance of the materials showed medium resistance or susceptibility when it carried one resistant gene, whereas materials carrying two or more resistant genes had more stable resistant levels. The analysis of variance showed that the mate-rials which carried 3 resistance genes had significantly higher resistance than that of Ty-1 or Ty-2 heterozygous disease resistance, but there were no significant differences between the loci with 2 resistance genes and single gene locus. The results of identification showed that there were 6 varieties with high resistance, 9 varieties showed resistance, 9 varieties showed medium resistance and 13 varieties showed susceptibility to TYLCV. The incidence of TYLCV in the identification nurseries was 58.03%, and tomato chlorosis virus (ToCV) was 4.67%. The resistance was significantly reduced after the co-infection with TYLCV and ToCV. The phenomenon implied that complex infection of TYLCV and ToCV may have potential adverse effects on the resistance genes. The above research results provide a theoretical basis for the application of disease resistance genes.

Lectin receptor-like kinase (LecRLK) is an important class of receptor-like protein kinases in plants that plays vital roles in plant response to various biotic and abiotic stresses. In this study, by analyzing the transcriptome data of wheat plants infected by Puccinia striiformis f. sp. tritici (Pst), we obtained a wheat lectin-like receptor kinase gene TaLecRLK1 that was significantly up-regulated during the wheat-Pst incompatible interaction. TaLecRLK1 contains a N-terminal signal peptide, an extracellular B-lectin domain, a PAN_AP domain, a transmembrane domain and an intracellular Pkinase-Tyr domain. Quantitative real-time PCR verified that TaLecRLK1 expression was induced in the early stage of wheat resistance to avirulent Pst infection. TaLecRLK1-GFP was located on the cell cytoplasmic membrane of Nicotiana benthamiana and wheat protoplasts. Virus induced gene silencing (VIGS) of TaLecRLK1 by barley stripe mosaic virus (BSMV) weakened wheat resistance to stripe rust, leading to sporadic production of uredinospores on TaLecRLK1-silencing wheat leaves challenged with Pst CYR23 that is avirulent on the control plants. Histological observation revealed longer infection hyphae in TaLecRLK1-silencing plants, along with decreased reactive oxygen species (ROS) accumulation per infection site compared with that in the control plants. In addition, the expression of defense-related genes TaPR1, TaPR2 and TaPR5 were decreased in TaLecRLK1-silencing plants, while the expression of TaCAT and TaSOD responsible for ROS scavenge were rapidly induced. These results indicate that TaLecRLK1 functions as positive regulator of wheat resistance to Pst.

To identify the virulence frequency and genetic diversity of Blumeria graminis f. sp. Tritici population, 34 wheat Cultivars (lines) with known Powdery mildew resistance genes and 5 pairs of ISSR markers were used in the study of virulence frequency and genetic diversity of isolates in Shaanxi Province respectively. The genetic diversity of 160 isolates from 15 towns in 6 cities, including Weinan, Xi′an, Xianyang, Baoji, Hanzhong and Ankang, Shaanxi Province, were collected in 2016. Results showed that the virulence frequencies of the resistance genes Pm1, Pm2, Pm3b, Pm3c, Pm3e, Pm3f, Pm6, Pm7, Pm8, Pm19 and Pm1+2+19 were 60%-100%, which meaned the Pm genes have lost resistance and value in production. While the virulence frequencies of Pm4b, Pm24, Pm2+6, Pm2+Mld, Pm2+6+?, Pm4b+Mli, Pm"Era", Pm"XBD" and Pm21 were less than 20%, which indicated the Pm genes have good resistance and value in wheat breeding. The analysis of 93 strains shows that the genetic distances were between 0.020 4-0.103 7, and the lowest value was between Baoji and Weinan, while the highest value was between Hanzhong and Xianyang. The genetic variation between populations accounted for 12.82% of the total variation, and the genetic variation within the population accounted for 87.12%, indicating that the genetic variation mainly come from within the population. Mantel Test illustrated that the genetic distance of wheat powdery mildew had little correlation with geographic distance.

In order to clarify the rice blast resistance and resistance genotypes of rice varieties that have been mainly planted in Jilin Province in recent years, a set of 25 standard strains of Magnaporthe oryzae with the identified avirulence genes were used for spray and wound inoculation. The results demonstrated that 68 rice varie-ties exhibited significant differences in blast resistance, and 44 varieties displayed moderate or high resistance, accounting for 64.7% of tested varieties. Postulation of blast resistance genes together with gene-specific molecular marker identification demonstrated that Pita, Pia, Pish, Pita2, Pib and Pi9 were the major blast resistance genes in Jilin Province. The number of blast resistance genes contained in the variety is positively correlated with blast resistance. Based on the results, none of these varieties contains Pi2, Pikh, Pikm, Pi11 or Pi12 genes. This study not only evaluated blast resistance and revealed blast resistance gene compositions of main rice varieties in Jilin Province but also clarified the contribution to blast resistance of major blast resistance genes and gene pyramiding in rice-growing region of Jilin. The results provide important references for breeding of broad-spectrum and durable blast resistance varieties and rational deployment of resistant varieties for the management of rice blast disease.

The objectives of this study were to evaluate the resistances of main commercial wheat cultivars to Fusarium crown rot (FCR) caused by Fusarium pseudograminearum in the Huanghuai winter wheat region by drip method at seedling stage and the mixed sowing method at adult stage and analyze the correlation of resistances between seedling and adult-plant stages. Fusarium mycotoxin accumulation in stems and kernels were also detected by Ultimate 3000-Q Exactive-Orbitrap in every cultivar. The results of the resistance to FCR showed that at seedling stage, 4 cultivars were resistant, accounting for 20% out of the 20 tested cultivars, such as ‘Bainong 207'; 7 cultivars were moderately resistant, accounting for 35%, such as ‘Zhengmai 7698'; 4 cultivars were susceptible, accounting for 20%, such as ‘Zhoumai 18'; 5 wheat cultivars were highly susceptible, accounting for 25%, such as ‘Aikang 58'. At adult-plant stage, ‘Zhoumai 18' and ‘Zhongmai 895' were resistant, accounting for 10%; 8 cultivars were moderately resistant, accounting for 40%, such as ‘Jimai 23'; 10 cultivars were susceptible, accounting for 50%, such as ‘Aikang 58'. There was no significant correlation between see-dling resistance and adult-plant resistance (P > 0.05). The results of toxin analysis showed that no toxin was detected in kernels of all the 20 wheat cultivars. Deoxynivalenol (DON, 4.03-17.65 mg·kg^-1) , zearalenone (ZEN, 0.09-1.28 mg·kg^-1) and the masked mycotoxin deoxynivalenol 3-glucoside (D3G, 1.93-16.82 mg·kg^-1) were all detected in stems, with different contents in different cultivars. At both seedling and adult-plant stages, ‘Zhengmai 7698' and ‘Aikang 58' were selected as the representative of moderately resistant and susceptible cultivars, respectively. This results provided basis for resistance evaluation of wheat to crown rot, and breeding and utilization of resistant cultivars.

To clarify the genetic structure of Sporisorium reilianum population in Shanxi province, 118 S. reilianum strains collected from 6 areas were analyzed by Simple Sequence Repeat (SSR) marker. A total of 30 alleles were detected using 12 pairs of primers. The mean number of alleles (Na), effective number of alleles (Ne), Shannon's information index (I) and allele richness (AR) were 2.5, 1.768 6, 0.614 4 and 2.175, respectively. The mean observed heterozygosity (Ho, 0.163 2) was lower than the expected (He, 0.396 5), and the inbreeding coefficient was positive (Fis, 0.522 1). The results indicate a few alleles in the S. reilianum population, which was relatively uniform in Shanxi Province. Due to the heterozygote deficiency, the geographical populations significantly deviated from Hardy-Weinberg. The genetic differentiations of the six geographical populations were all at the medium level (FST = 0.050 - 0.055), and genes of the populations exchanged frequently (Nm =1.563-121.109). Analysis of molecular variance (AMOVA) further showed that the genetic variation mainly occurred within the populations(94.80%), while only 5.2% among populations. The UPGMA dendrogram analysis separated the tested populations into two genetically differentiated subgroups: the first subgroup included two populations (Jincheng and Changzhi) from southeast Shanxi, the second subgroup made up of four populations from central and northern Shanxi. This result was in agreement with structure-based analysis. Collectively, we inferred that the populations of S. reilianum in Shanxi province may come from two ancestral subpopulations, and the genetic components of most strains are single. Our findings provide a theoretical basis for the integrated control of corn head smut.

Black point disease, caused by the dominant pathogen Bipolaris sorokiniana, is a severe wheat grain disease. In order to analyze the genetic characters and detect the resistance loci for black point, the resistant genotype Shannong4143 and susceptible genotype Wanyuanbai1 and their recombinant inbred line (RIL) population at F₇ were planted at three experimental locations in 2018-2019 wheat growing season. Resistance identification was carried out using the method of spraying spore suspension of B. sorokiniana and bagging for moisture. The genetic analysis was carried out by mixed inheritance model of major genes plus polygenes. The extreme resistant and susceptible inbred lines were selected to build a mixed pool. Combining 660K SNP arrays, the resistant loci were detected by bulked segregate analysis (BSA). The results showed that: the resistance of wheat to black point caused by B. sorokiniana was in accordance with the "additive - epistatic inheritance model of 4 major genes", and heritability of the major gene was 0.88-0.95. Thirty-six loci were detected by BSA, which were located on 14 chromosomes of 1A, 2B (6), 2D (2), 3A, 3B (2), 3D, 4A (6), 4D, 5A (4), 5B (6), 5D (3), 7A, 7B and 7D, respectively. A total of 13, 15, and 8 loci were from the A, B, and D genomes, respectively. Among the 36 loci detected, 18 loci were new loci for resistance to black point. The results of this study laid a foundation for the fine mapping of resistance loci to black point and development of molecular markers in the breeding for resistant cultivars to black point.

Rice and Magnaporthe oryzae (M. oryzae) constitutes an ideal pathosystem for studying host-pathogen interaction in cereals crops. Luoping County, southwest China's Yunnan Province, is a main rice-producing area and one of the major hotspots of rice blast disease. In the field, the composition of M. oryzae population is complex and the information flow is strong. The isolation of single spore strains and the study of avirulence genes are the important basis for revealing the mechanism of virulence variation of M. oryzae and the comprehensive control of rice blast disease. In this study, we isolated 120 single spore strains from the field samples collec-ted from Luoping in 2017. The morphology, sporulation capacity, presence/absence (P/A) polymorphisms of seven avirulence (Avr) genes, and the relationship between avirulence gene variation and pathogenicity of these strains were studied systematically. Our results showed that the culture characteristics and sporulation ability were diversity among strains. The P/A frequency of seven Avr genes in 120 field strains was different, in which ACE1, Pwl2, and Avr-Pizt had the highest frequency of 100%, Avr-Pia had the lowest frequency of 5%, and Avr-Pita1, Avr-Pik, Avr-Pii were 99%, 99%, and 89%, respectively. Importantly, thirty-three M. oryzae isolates containing three Avr-Pik allele copies were identified for the first time. The rice monogenic lines were susceptible to the strains with the corresponding Avr genes complete deletion or functional variation. This result indicated that pathogen could shed off or modify its Avr gene to dodge past the resistance mechanism of the host plant thus making it susceptible. Our findings not only enrich the genetic resources of M. oryzae, lay an important foundation for studying the mechanisms of rice-M. oryzae interaction, but also provide valuable information for controlling rice blast disease.

In order to clarify the species and pathogenicity of black rot strains in central cabbage productive areas of China, and provide a basis for optimizing the identification methods of disease resistance, screening resistant varieties and rational distribution of resistant varieties, black rot disease leaves were collected from 10 provinces. After isolation, purification and molecular identification, 26 typical strains from central cabbage productive areas in 10 different provinces were obtained. 5 cabbage resistant and susceptible varieties were selected as the test hosts. The suspension of the black rot strain was an inoculum and the pathogenicity was determined by a spray inoculation method. The results showed that there were significant differences in the pathogenicity of black rot strains from different provinces. The most pathogenic strainis YU and the average disease index is 38.31. The weakest strain is SH and the disease index is 17.03. The most virulent cabbage black rot strain from different altitudes is G1500, the average disease index is 37.93; the weakest is G800, the average disease index is 19.80. According to the identification of host anti-infective reaction, 26 black rot strains can be preliminarily classified into 12 types of pathogenic types. It was found that there were significant pathogenic differentiation among cabbage black rot strains from different regions, and there were significant differences in the pathogenicity to cabbage varieties. Among them, strain YU led to strongest pathogenicity, and can be used as the main pathogenic strain for the identification of disease resistance of cabbage, which guides the breeding of resistant varieties.

Spot blotch, caused by the fungal pathogen Bipolaris sorokiniana (Sacc.) Shoemaker, is one of the important foliar diseases on barley, which can cause serious yield losses in the barley-growing regions worldwide. In this study, three Bs isolates (Z 12010, Z 12014, and Z 13010) with different patterns of pathogenicity were used to test the spot blotch resistance of 61 barley germplasm accessions collected from China and other countries at the seedling stage. The adult-plant resistance to spot blotch in this set of barley germplasms was evaluated by inoculating isolate Z 12014 in the field. There was no barley accession showing immune reaction to spot blotch. Significant difference in the seedling resistance were found among the accessions against the three pathogenic isolates. Twelve accessions, Varunda, Legacy, Tradition, 09GW-01, 09GW-07, 08PJ-36, 09PJ-39, Kenpimai 7, Kenpimai 10, Zhudamai 3, S-4, and Zhongsimai 1, were moderately or highly resistant to the three isolates examined. Seven barley accessions were resistant to isolate Z 12014 at the adult-plant stage, of which 6 accessions, Legacy, Mengpimai 3, 09PJ-39, Kenpimai 9, Kenpimai 11, and Longpimai 3, showed all-stage resistance, and variety 10-3 was susceptible at the seedling stage but resistant at the adult-plant stage to isolate Z 12014.

Tibetan semi-wild wheat (Triticum aestivum ssp. tibetanum Shao), Yunnan hulled wheat (T. aestivum ssp. yunnanense King) and Xinjiang rice wheat (T. petropavlovskyi Udacz et Migusch) are unique germplasm resources and have specific geographical distribution in China. Morphological characteristics of them are obviously different from common wheat (T. aestivum L.). Besides, disease resistance and tolerance can be used for improvement of modern wheat variety under biotic and abiotic stress. In this study, 213 accessions of Chinese endemic wheat (including 117 Tibetan semi-wild wheat, 78 Yunnan hulled wheat and 18 Xinjiang rice wheat) were inoculated with mixed races of wheat stripe rust to evaluate the resistance during seedling and adult stage, respectively. Meanwhile, molecular markers linked to twelve known resistance genes were used to detect the resistance genes. The results showed that 18 accessions were resistant at seedling stage, as well as 89 accessions displayed stable resistance at adult stage. Moreover, these resistant accessions mainly derived from Yunnan hulled wheat. By integrating all information of the pedigree of these accessions, resistance to stripe rust races, and molecular detection, it showed that only 2 accessions carried Yr18 and the 213 accessions were not detected to carry Yr5, Yr9, Yr10, Yr15, Yr17, Yr24/Yr26, Yr30, Yr41, Yr48, Yr65 and Yr67. These results indicated that the resistant accessions may contain other known or new resistance genes. The results will provide the information for further effective utilization of stripe rust resistance germplasms of Chinese endemic wheat subspecies and discovery of their resistance genes.

Watermelon mosaic virus (WMV; genus Potyvirus) is an important viral pathogen infecting cucurbit crops in China. Breeding and planting resistant varieties are the most economical and effective strategy to control viral disease. In this study, WMV but not papaya ringspot virus (PRSV) was detected on fruits of zucchini exhibiting ringspot symptoms by RT-PCR and virus specific antibodies. Zucchini cultivar ‘LvYuanDongBao' plants inoculated with WMV infectious clone pCamWMV-GFP showed ringspots on fruits, suggesting WMV is an important pathogen causing ringspot symptoms on zucchini fruits. In total, 46 samples collected from watermelon, cucumber, melons, zucchini and pumpkin plants in Tai'an, Shandong, were tested by WMV specific antibody using Plate Trapped Antibody-Enzyme Linked Immuno Sorbent Assay (PTA-ELISA). Results showed that 33 samples were WMV positive (71.74%). Zucchini fruits displaying ringspot symptoms from Xuezhuang were all WMV positive. Resistance to WMV in 81 cucurbit crops germplasm resources from Shandong Province was identified. Results showed that zucchini cultivars ‘Wanshengfengbao' and ‘Shengfengjinzhu' were moderately resistant to WMV; watermelon cultivars ‘Lvbaoxinxiu' and ‘Langchao 1' were moderately resistant to WMV; melon cultivar ‘Huangpimian melon' was resistant to WMV; cucumber cultivar ‘Xingjun beibei' were moderately resistant to WMV; pumpkin cultivar ‘Aiwei 80 pumpkin' was highly resistant, and five cultivars including ‘Miben pumpkin', ‘traditional Miben pumpkin', ‘Qiye early pumpkin', ‘Linglong 2' and ‘Green beibei mini pumpkin' showed resistance to WMV. All tested bottle gourd cultivars were susceptible or highly susceptible to WMV. These results will be helpful to control WMV by utilizing resistance of different cucurbit crops.

In order to clarify the genetic diversity of Pratylenchus neglectus populations in China, the genetic structure and genetic differentiation of 9 geographical populations were analyzed using the mtCOI gene as the marker. The results showed that a total of 101 mtCOI sequences were obtained from 9 populations, 28 variable nucleotide sites were discovered, and 14 haplotypes were formed. The haplotype H1 was the most common one shared by 59 individuals from 7 populations, which was speculated might be the ancestral haplotype. All the geographical populations showed the moderate genetic diversity at the species level (H_T = 0.706±0.131), and the cluster analysis showed that they could be divided into two groups, as the Group Ⅰ and Group Ⅱ. The AMOVA analysis revealed that the genetic differentiation at the whole level of P. neglectus populations was mainly derived from the inter-populations. The Mantel test showed that the genetic distance among P. neglectus populations was positively correlated with their geographical distance, although there was no significant correlation between the genetic differentiation and the geographical distance among different populations. Both the neutrality test and the mismatch distribution test revealed that the historical dynamics of P. neglectus populations at the whole level as well as at the two-groups level were relatively stable.

To determine the distribution of Trichotylenchus changlingensis in different geographical populations, in 2018, nematodes were isolated and identified from the rhizosphere soil of maize in 118 regions of Heilongjiang, Jilin, Liaoning, Hebei, Inner Mongolia and Gansu provinces (autonomous regions). The results showed that the nematodes were isolated from 20 soil samples in 6 provinces (autonomous regions) with isolation frequency of 17.0%. Sixteen highly polymorphic and reproducible ISSR primers were screened out and were used to amplify the 20 T. changlingensis isolates. A total of 93 polymorphic bands were obtained with a polymorphism ratio of 93.55%. The genetic differentiation coefficient (Gst) was 0.4771, indicating that the inter-group component accounted for 47.71% of the total variation,while the inner-group component accounted for 52.29%. The gene flow (Nm) was 0.5479 indicating that there was a less gene flow among different geographical populations. But there was genetic differentiation of some extent among groups. UPGMA cluster analysis showed that the T. changlingensis was rich in genetic diversity and there was no significant correlation between genetic distance and geographical distance.

In order to clarify the pathogen of maize gray leaf spot disease in the Huanghuaihai summer maize region, samples were gathered from 76 counties suspected to have this disease in Hebei, Henan, Shandong, Anhui and Tianjin in 2017. Isolates were obtained by tissue separation and single spore isolation and were identified by morphological and molecular methods. ISSR clustering analysis performed on 37 isolates from Huanghuaihai region, Shaanxi, Liaoning and Heilongjiang. The results showed that Cercospora zeae-maydis was the pathogen of maize gray leaf spot disease in Huanghuaihai region, and the variation of C. zeae-maydis had geographical population characteristics. Moreover, artificial inoculation identification of maize main cultivars in Huanghuaihai summer maize region showed that four of the six main cultivars (Zhengdan 958, Denghai 605, Xianyu 335, and Xundan 20) exhibited low resistances to gray leaf spot, so this disease had a large risk of occurrence and prevalence in this region. This study provided a theoretical basis for comprehensive prevention and control of gray leaf spot disease in Huanghuaihai summer maize region.

Stripe rust is one of the most serious diseases affecting wheat yield. The most effective way to control stripe rust is using the molecule method to find the quantitative trait loci (QTL). To explore trueand main QTLs for stripe rust resistance, a total of 342QTLs from different genetic mappingpopulations in wheat were carried out by meta-analysis technique and constructed the consistency map depending on wheat Yr genes and QTL genetic maps and DArT4.0 genetic maps as reference maps. The results showed that 194 QTLs overlapped the same marker intervals with the reference map. Among these QTLs, 74 and 46 QTLs were related to disease severity (DS) and infection type (IT), respectively. The other QTLs were involved in area under the disease progress curve (AUDPC, 19QTLS), DS and IT (28 QTLs), DS and AUDPC (6 QTLs), IT and AUDPC (15QTLs), and the other index (6 QTLs). The QTL consistency map of wheat stripe rust resistance was constructed. The MQTLs showed non-uniform distribution and some MQTLs were clustered on wheat chromosomes. Meanwhile, comparing the MQTL clusters with the officially named Yr genes, it showed that some clusters and Yrgeneswere located at the same chromosome regions. It indicated that these chromosomal regions maybe the hotspot regions for stripe rust genes. So, the linkage map of the meta quantitative trait loci on stripe rust resistance in wheat might provide theoretical idea for fine mapping and cloning of QTL controlling stripe rust in wheat.

For clarifying the resistance level of wheat cultivars or lines developed in Heilongjiang to Puccinia graminis f. sp. tritici (Pgt) and finding out the stem rust resistance genes utilization in them, the seedling stem rust resistance of 83 major wheat cultivars or lines collected from Heilongjiang were evaluated with predominant Chinese Pgt races 21C3CTHQM, 34MKGQM and 34C3RTGQM in this study. Besides, molecular markers closely linked with genes Sr2, Sr24, Sr25, Sr26, Sr31, and Sr38 were used for molecular identification. Resistance genes possibly carried in the cultivars were analyzed based on the results of molecular identification, seedling reaction types as well as cultivar pedigrees. The results showed that all tested wheat cultivars or lines were resistant to the three tested races. Among them, 57, 53 and 60 of the 83 cultivars were immune or nearly immune to 21C3CTHQM, 34MKGQM and 34C3RTGQM, namely accounting for 68.68%, 63.85% and 72.29% of the total cultivars, respectively. The rest others remained moderately or highly resistant to the tested races. With molecular marker analysis, 12 of 83 wheat cultivars or lines possibly carry gene Sr2, Sr25 tested in Kehan 3, and Sr31 and Sr38 in 6 and 19 wheat cultivars respectively. Both genes Sr24 and Sr26 were not detected in any tested cultivar. Therefore, wheat cultivars developed in Heilongjiang Province was relatively highly resistant to stem rust. Most of them carry resistance gene Sr2, and/or Sr31 and Sr38 being resistant to all Chinese Pgt races, and/or possible other unknown resistance genes. These highly resistant wheat cultivars can be used as effective resistance resources for future wheat breeding.

Sclerotinia sclerotiorum is a worldwide pathogenic fungus causing serious diseases on many economically important crops. Studying on the genetic diversity of S. sclerotiorum isolates from different eco-geographical regions is crucially important for understanding the evolution of this fungal pathogen and disease control. In this study, DNA polymorphism of 66 S. sclerotiorum isolates derived from 17 different regions in Sichuan pro-vince were detected using sequence-related amplified polymorphism (SRAP) markers. A total of 129 scorable fragments were identified with 10 SRAP primer combinations, among which 123 were polymorphic loci (95.35%). UPMGA (Unweighted Pair Group Method with Arithmetic Mean) indicated that the dendrogram consisted of five groups (Ⅰ, Ⅱ, Ⅲ, Ⅳ and Ⅴ) at the genetic similarity coefficient of 0.70, which included 60, 2, 2, 1 and 1 isolates, respectively. Moreover, the group Ⅰ contained three sub-groups (I-1, I-2, I-3) at the genetic similarity coefficient of 0.74, which included 21, 37 and 2 isolates, respectively. This study showed a rich SRAP polymorphism among the populations of S. sclerotiorum in Sichuan province, but genetic diversity had no significant correlation with geographical location.

Glomerella leaf spot of apple (GLSA) is mainly caused by Colletotrichum gloeosporioides, which has become a major apple leaf disease and threatens apple growth. A mutant strain A3083 that lost pathogenicity was obtained by screening the T-DNA insertional mutant library. Southern blot analysis indicated that A3083 contains a single copy of T-DNA. The T-DNA right flanking sequence of A3083 obtained by hiTAIL-PCR was aligned with the whole genome of C. gloeosporioides, which showed that the T-DNA is located in the coding region of a predicted gene CGGC5_9603. This gene was designated as CgNVF1, which is 2 252 bp in length, contains 2 introns and encodes 709 amino acids. Fluorescent signal showed that the fused protein CgNVF1-eGFP is distributed to the cytoplasm and expressed in all of the mycelium, conidium and appressorium. Phenotypic analysis of the CgNVF1 knockout mutant and the complementation strain indicated CgNVF1 is required for appressorium formation and pathogenicity in C. gloeosporioides.

Survey for occurrence of potato Verticillium wilt (PVW), collection of the diseased samples and pathogen isolation were carried out in 245 potato production fields distributed in 53 counties of 7 provinces in China from 2013 to 2016. Molecular and biological methods was employed for the classification of the pathogens and the pathogenicity differentiation of Verticillium dahliae causing PVW was evaluated in greenhouse. Results indicated that PVW was found throughout the 6 provinces in northern China covering Inner Mongolia, Hebei, Gansu, Heilongjiang, Shanxi and Ningxia, but not in Yunnan province. The pathogen causing PVW was identified as V. dahliae (Vd) and V. albo-atrum (Vaa), and V. dahliae was the major pathogen with isolation proportion of 75.5%. The diseased fields over the 6 provinces in northern China could be divided into 3 different types including Vd-only, Vaa-only and Mixed pathogens field based on the distribution of the pathogens. The Vd-only pathogen field was only found in Gansu, the Mixed pathogens field only in Ningxia, Vd-only and Mixed pathogens field in Shanxi, and 3 types diseased fields were found in Inner Mongolia, Hebei and Heilongjiang province. All kinds of pathogens in the Mixed pathogens field belonged to individual infection. Clustering analysis of the pathogen’s pathogenicity was carried out by using 82 isolates of V. dahliae from Gansu, Hebei and Inner Mongolia. The result showed that all tested pathogen isolates could be clustered into at least 3 groups, and the AUDPC mean corresponding to the different cluster groups showed significant differences at P<0.05. In addition, the isolates could be divided into 3 pathogenic types of strong, weak and moderate, while the 95% confidence intervals were calculated correspondingly. Among them, the proportion of strong pathogenic isolates in 3 provinces was 3.33%, 21.74% and 10.34%, respectively.

Verticillium wilt caused by Verticillium dahlia is one of the most important diseases on cotton and eggplants in China, which causes a significant reduction in yield of both crops. In order to reveal the population genetic variation and the cross-pathogenicity between V. dahliae isolates collected from cotton and eggplants , a V. dahliae population of 63 isolates from cotton and 10 isolates from eggplants in Jiangsu province was characte-rized in terms of the cultural morphology, genetic and phytopathogenic characterizations. According to the quantity of microsclerotia of the colonial morphology on PDA, the isolates were divided into three cultural types and the sclerotia type was the main group accounted for 83.6%. The pathotype, mating type and containing avirulence gene Ave1 were analyzed by PCR. The results showed that the defoliating pathotype was the dominant group accounted for 86.3%, but 100% of 10 isolates from eggplants in Jiangsu province were genotyped as nondefoliating. All of isolates from Jiangsu province were genotyped as MAT1-2, and there was no avirulence gene Ave1 in their genomes. The cross-pathogenicity of 6 isolates from cotton and 4 isolates from eggplants was determined by artificial inoculation on seedlings of cotton and eggplant. All 10 isolates could infect both hosts, and the pathogenicity varied not only among the different isolates to the same host but also on different hosts with the same isolate. These results will lay foundations for in-depth study of the genetic population structure of V. dahlia and for development of the disease control measures.

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.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is the most devastating wheat disease in China. Wheat growing region of Sichuan Province plays a key role for stripe rust spread and epidemic in China. To evaluate the resistant level and detect the stripe rust resistance gene(s) of commercial wheat cultivars and advanced lines in Sichuan Province, 100 wheat cultivars (lines) collected from Sichuan Province were inoculated with Chinese Pst races G22-83, CYR32 and CYR33 at the seedling stage, and the genomic DNA of these cultivars (lines) were tested with the closely linked markers of all-stage resistance genes Yr5, Yr9, Yr10, Yr15, Yr26 and adult-plant resistance gene Yr18. The disease evaluation results indicated that 58%, 63% and 43% wheat cultivars (lines) showed resistance to CYR32, CYR33 and G22-83 in the seedling tests, respectively. Among these, 28 cultivars (lines) were resistant to all three Pst races. Molecular detection suggested that the resistance genes Yr9, Yr10, Yr15 and Yr26 were found in 24%, 9%, 5% and 26% cultivars (lines), respectively. There was no indication of Yr5 and Yr18 in any cultivar (lines).

Rice kernel smut pathogen attacking primarily male sterile lines, is the main pathogenic factor that affects the yield and quality of hybrid rice seed reproduction in southern of China. In order to excavate rice varieties resistant to kernel smut, and provide resistant rice sterile materials for breeding, seventy-eight male sterile rice lines from Hubei, Fujian and Sichuan were evaluated at the heading period by inoculating with Tilletia horrida during 2014-2016. The results showed that the most of the seventy-eight lines were susceptible, but four of them were resistant to rice kernel smut pathogen. Among them, 4766A was the first cultivar highly resistant to rice kernel smut in China.

The objective of this study was to evaluate the pathogenicity of Fusarium acuminatum isolates to various alfalfa varieties. Fourteen varieties of alfalfa were inoculated with 15 F. acuminatum isolates obtained from alfalfa roots collected at 4 locations. The relative root length, relative seedling height, relative germination rate and disease index were assayed at 14 days after inoculation. The results indicated that the root length of alfalfa seedlings was significantly reduced by all of the 15 isolates (P<0.05). Overall, the pathogenicity of each isolate varied among the 15 isolates. The isolate from ‘WL-323HQ’ exhibited the strongest pathogenicity, while the isolate from ‘WL-525HQ’ (planted in experimental area of Neihuang County of Anyang City) showed the weakest pathogenicity. The isolates from ‘WL-525HQ’ (planted in experimental area in Zhengzhou City), ‘Legacy’ , ‘Affinity’ and ‘Millionaire’ showed strong pathogenicity, while the isolates from ‘Aohan’, ‘Farmers’, ‘WL-323ML’ and ‘Dingdian’ showed weak pathogenicity. The disease resistance of the 14 alfalfa varieties also varied, among of them, ‘Amerimultileaf’ showed the strongest resistance. ‘Amerileaf721’, ‘Victoria’, ‘Powerplant’ and ‘Legacy’ exhibited high-level resistance. ‘Sandy’, ‘Phabulous’, ‘Hunter river’ and ‘Alfaking’ showed low-level resistance. ‘Vernal’ had the weakest resistance.

Wheat stripe rust were monitored using hyper-spectrometer and UAV aerial photography in the field, respectively. The relationships among disease index and hyperspectral canopy reflectance parameters or UAV digital image parameters were analyzed. The results showed that there were significantly correlations between disease index and the hyperspectral parameters (DVI, NDVI, GNDVI) or UAV digital image color feature parameters (R, G, B). In general, the correlations between hyperspectral parameters and disease index were higher than those between UAV digital image parameters and the disease index. Furthermore, hyperspectral parameters DVI, NDVI, GNDVI were negatively and significantly correlated with UAV digital image parameters R, G, B. We constructed the estimation models of wheat stripe rust based on hyperspectral parameter GNDVI and UAV digital image parameter R, respectively, both the models fitted well, and the model based on GNDVI performed better than the model based on R, however, UAV digital images have the advantages of undertaking fast detection in large area, so in practice, we can choose one methods or one of the parameters to estimate the occurrence and epidemic of wheat stripe rust in the field as needed.

Strawberry gray mold caused by Botrytis cinerea Pers. is an important infectious disease, which can cause fruit rot of strawberry and gives a great threat to fruit yields and post-harvest fruits of strawberry. To study the epidemics of strawberry gray mold in greenhouse and to investigate the corresponding influence factors, the number of airborne conidia of B. cinerea, the rate of petals infected by the fungus and the number of new diseased fruits were dynamically monitored in the growing seasons of 2013 to 2014 and 2014 to 2015, respectively. Combining with meteorological factors recorded in the greenhouse, all collected data were analyzed. The results showed that the airborne conidia concentration of B. cinerea was high from 5:00 to 18:00, especially during 11:00 to 14:00 in one day. The analysis results based on the obtained data in the two growing seasons of strawberry demonstrated that the hourly number of trapped conidia had highly significant positive correlation with temperature and light intensity (P≤0.01), and had highly significant negative correlation with relative humidity (P≤0.01). The number of new diseased fruits had highly significant positive correlation with both the number of trapped conidia (r=0.872, P≤0.01) and the infection rate of the fresh petals (r=0.807, P≤0.01) on the seventh day before the corresponding fruit survey, indicating that this number of trapped conidia and this infection rate could be used as references to predict strawberry gray mold seven days in advance. The results of this study are helpful to understand the occurrence and influence factors of strawberry gray mold in greenhouse, and have provided some basis for the prevention and control of this disease.

Xanthomonas oryzae pv. oryzicola depends on Type III secretion system (T3SS) to cause disease in host plant rice. T3SS is encoded by hrp (hypersensitive response and pathogenicity), hrc (hrp conserved) and hpa (hrp associated) genes. Mutations of essential hrp or hrc genes usually abolish the bacterial ability to cause pathogenicity in host rice and hypersensitive response (HR) in non-host tobacco. The hrpD5 gene is the fifth gene with unknown function located in the hrpD operon of the hrp gene cluster. In this work, we constructed a deletion mutant of hrpD5 in Xoc strain RS105 (named as RΔhrpD5). Inoculation assays showed that RΔhrpD5 was not able to cause pathogenicity in host rice and failed to trigger HR in non-host tobacco. The lost functions were partially restored in the complementary strain CRΔhrpD5 which had reduced virulence on the susceptible rice and caused delayed HR on non-host tobacco compared to the wild type. Transcriptional analysis showed that mutation of hrpD5 affected the expression of downstream genes hrpD6, hrpE and hpaB in the hrpD operon and genes hrpF and hrpB1 in the HrpX operon, and led to decreased level of hrpX mRNA, but didn′t affect the promoter activity of hrpX. The yeast two-hybrid analysis revealed that HrpD5 interacted with the N terminal of HrpF. These results indicate that hrpD5 not only is essential for the pathogenicity of Xoc, but also regulates the expression of hrpX, the major hrp regulatory gene. Further functional investigation of HrpD5 may provide some clues to elucidate the roles of T3SS in pathogenicity of Xoc.

RsmA belongs to a conserved family of RNA binding proteins (CrsA/RsmA family) functioning as a global post transcriptional regulator and has been demonstrated to regulate carbon metabolism, biofilm formation, motility, and the expression of pathogenicity genes. Homology search showed that there was a rsmA gene in Xoc strain RS105, which shares a 100% identity with rsmA_Xoc gene of a Xoo strain PXO99A. However, its function in Xoc remains unclear. In this work, we constructed a deletion mutant of rsmA gene in Xoc RS105 strain named as RΔrsmA. Inoculation assays showed that RΔrsmA can cause pathogenicity on host rice, and trigger a hypersensitive response on non host tobacco, which exhibits a different phenotype from that of the rsmA_Xoo mutant. However, compared with the wild type strain, significantly reduced virulence symptoms on susceptible rice were observed in the RΔrsmA mutant, and bacterial growths in nutrient rich and poor medium were also weakened. In addition, the RΔrsmA mutant showed weaker ability of swimming motility on semisolid medium, increased biofilm, decreased level of extracellular polysaccharide, but was enhanced in secreting extracellular proteases when compared with the wild type strain. These results indicate that rsmA is essential for the virulence of Xoc and there are some differences in functions of RsmA as virulence regulators in Xoo and Xoc. Therefore, identification of downstream genes regulated by rsmA may provide clues to elucidate the different roles in pathogenicity in the two pathovar strains of Xanthomonas oryzae.

To investigate the pathogenicity differentiation levels of Xanthomonas oryzae pv. oryzicola (Xoc), six differential cultivars, IRBB5, IRBB14, IR24, IRBB4, IRBB21 and Jingang 30,were used to identify 129 Xoc strains isolated from six rice growing areas in Jiangxi Province. These Xoc strains were classified into nine pathotypes from C1 to C9 according to their pathogenicity, whereas, only C5 and C7 showed strong interaction with differential cultivars IRBB4 and IRBB21, respectively. In addition, the predominant Xoc pathotypes in different rice growing areas showed diversity. Also, three typical Xoc strains were used to inoculate 124 indica rice varieties and 252 Dongxiang wild rice varieties during the booting stage, the results indicated that among 124 indica rice varieties, 8.06% varieties exhibited moderate resistance to the C2 strain 5 16 and 14.5% exhibited resis tance to the C6 strain 08 3 2; for 252 Dongxiang wild rice varieties, only one, Dong 113, exhibited high level resistance and 14 showed resistance to the C2 strain. The seedling stage resistance identification results of 252 Dongxiang wild rice varieties suggested that there were significant correlation between the seedling stage resis tance and the booting stage resistance, However, the seedling stage resistance of most of the varieties are generally weaker than that of the booting stage resistance, only Dong 113 exhibited moderate resistance to the C2 strain. Taken together, disease resistance of the Dongxiang wild rice varieties to Xoc are higher than that of the cultivated rice varieties, and looking for resistance genes from the Dongxiang wild rice varieties will be one of the perfect ways to develop disease resistant varieties to Xoc.

Citrus Huanglongbing is one of the most devastating diseases threatening the healthy development of global citrus industry. The causal agent is a phloem limited bacterium. Candidatus Liberibacter asiaticus (CaLas) is the only pathogen associated with Citrus Huanglongbing in China. Due to the difficulty of in vitro culture, very little is known about the molecular mechanism of pathogenicity of CaLas. In the present study, three putative pathogenicity related genes of Pal_CaLas, Mot_CaLas and Hly_CaLas were selected from the whole genome sequence of CaLas (Psy62: NC_012985.1) according to the characteristics of pathogenicity related genes available to other similar plant pathogenic bacteria reported. The above 3 genes were constructed to the plant expression vector psk103 via BP and LR reaction respectively based on the homologous recombination of Gateway technology. Agrobacterium mediated transient expression method was used to analyze the phenotype induced by 3 genes in Nicotiana benthamiana. Our result showed that Pal_CaLas, Mot_CaLas and Hly_CaLas were correctly constructed to psk103 vector as confirmed by PCR products cloning and sequencing. Transient expression in N. bentha miana indicated: Pal_CaLas construct successfully induced a strong hypersensitive response at 4dpi when inoculated with Agrobacterium OD₆₀₀ in the range of 0.3 0.8 to 6 week old N. benthamiana. None of the other two constructs of Mot_CaLas or Hly_CaLas gave similar reaction under the same circumstance. With time progressed, stronger HR response was observed. And the whole leaf became necrosis at 12 dpi after infiltration of Pal_CaLas. In conclusion, Gateway is a powerful technique for the successful screening of pathogenicity related genes from CaLas. And this is the first report nation wide for quick screening of pathogenicity related genes from CaLas which laid a basic foundation for future research on the molecular mechanism of host pathogen interactions.

Rice blast is an important disease which influences rice production. The field monitoring on the configuration of rice blast pathotypes is essentially needed for effective disease controlling by growing resistant varieties. In the present study, blast panicle specimens were collected from 10 rice areas in Hubei province in 2015. The pathogenicity of each single spore strain was determined on a series of single-gene differential lines. Also, blast resistances of 25 rice cultivars were identified by inoculating with spore solution from 10 rice regions. The results showed that the pathotypic structure from different rice regions was diverse, and the resis-tances of 25 cultivars were significantly different. The infection degrees of the 9 resistance genes among single-gene lines in Hubei were also different.

Sugarcane brown rust is one of the most widespread and destructive diseases in main sugarcane plan-ting areas in China. Breeding and growing resistant cultivars are the most economic and effective measures for controlling this disease. To determine the sugarcane brown rust resistance and their application potential of 50 new elite sugarcane varieties/lines bred from China Sugarcane System in recent years, the linked molecular markers of brown rust resistance gene Bru1 were used to test these 50 varieties/lines using two commercial varieties as control. Meanwhile, the disease resistance to brown rust of these cultivars/lines was investigated and analyzed under natural inoculation at the Comprehensive Experimental Station of the China Sugarcane System in Dehong and Baoshan, where brown rust are frequent and severe, in Yunnan in 2014 and 2015. Field surveys indicated that 34 out of 50 new elite varieties/lines and two control varieties (65.38%) showed highly resistant to moderately resistant. Of these, fifteen (28.85%) were highly resistant, sixteen (30.77%) were resistant and three (5.77%) were moderately resistant. Molecular detection results suggested that Bru1 was present in 29 (55.77%) materials out of the 34 resistant cultivars/lines, indicating that brown rust resistance in new elite sugarcane varieties/lines in China is primarily controlled by Bru1. The absence of Bru1 in the other 5 resistant varieties/lines suggests that they may carry other brown rust resistance-associated genes. The frequencies of susceptible varieties in field and varieties carrying Bru1 gene were different in different series of sugarcane varieties. The resistance of Yuetang series of sugarcane varieties was the weakest which have the highest frequency (60%) of susceptible varieties and the lowest Bru1 frequency (30%); the resistance of Yunzhe series of sugarcane varieties was the best which have the lowest frequency (12.5%) of susceptible varieties and the highest Bru1 frequency (81.25%). These results may facilitate brown rust resistance breeding and provide new elite resistant varieties for sugarcane brown rust effectively control.

The gene postulation of wheat landraces Hongtutou and Bawangbian showed that they had wide resistance spectrum and may carry new powdery mildew resistance genes. Genetic analysis showed that the resis-tance of wheat landrace Hongtutou to powdery mildew pathogen isolate E09 was controlled by a single dominant gene and the resistance to isolates E26 and E30-2 was controlled by a single recessive gene separately. The resis-tance of Bawangbian to isolates E09 and E26 was separately controlled by two dominant genes and the resistance to isolate E30-2 was controlled by a single dominant gene. Illumina wheat 90K single nucleotide polymorphism (SNP) array with bulk segregant analysis (BSA) was performed to determine the chromosomal locations of the resistance genes. The results indicated that the resistance genes to wheat powdery mildew in Hongtutou may be located on chromosomes 7B and 6B, and those in Bawangbian may be located on chromosomes 4A and 7B.

Powdery mildew resistance genes in wheat cultivars (lines) from major Chinese wheat regions were studied by using gene postulation and molecular markers. The results indicated that Pm8 was the most postulated or detected genes carried by fifteen cultivars (lines). Pm4 presented in nine cultivars (lines). Pm21 presented in nine cultivars (lines). Zhengmai113 was postulated to possess Pm4b+5b. Yang 09-111 and Xinzi No.1 was postulated to possess Pm2+mld . The results showed that the combination of gene postulation and molecular markers can greatly improve the accuracy of the identification to powdery mildew resistance gene in wheat cultivars (lines). The identification results can provide the basis for disease resistance breeding, cultivar deployment the prevention and control of powdery mildew.