[Objective] The research aimed to study the relationship between the hypersensitive response of wheat to Blumeria graminis f.sp.tritici and hydrogen peroxide,3 enzyme activities changes and lay the foundation for disc...[Objective] The research aimed to study the relationship between the hypersensitive response of wheat to Blumeria graminis f.sp.tritici and hydrogen peroxide,3 enzyme activities changes and lay the foundation for discussing the resistant physiological mechanism of wheat to B.graminis.[Method] Taking B.graminis Bgt 17 and Bgt 6 and wheat cultivar Yang 158 as test materials,the number of hypersensitive cells and activities of POD,PPO and SOD in wheat leaves treated by H2O2 were determined.[Result] The mastoid...展开更多
This paper reviewed the research advances of Ug99 and its resistance breeding from the aspects of its discovery, race variation, pathogenicity, distribution, spread, exploration of relative resistant genes, linked mol...This paper reviewed the research advances of Ug99 and its resistance breeding from the aspects of its discovery, race variation, pathogenicity, distribution, spread, exploration of relative resistant genes, linked molecular marker selection and resistance breeding strategies, to provide basis for comprehensive understanding of the new Puccinia graminis f. sp. tritici race Ug99 and its potential threat to wheat production. Ug99 is a new Puccinia grarninis f. sp. tritici race with high variability, strong pathogenicity and rapid spread speed, which is likely to cause global damages to world wheat production. We should strengthen the exploration and utilization of new resistance genes in wheat and relative species and breeding of new wheat varieties with durable resistance, to control and prevent damages caused by Ug99 and its variants.展开更多
Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, is an important disease in China. To characterize the virulence and diversity of the pathogen, 1 082 isolates were obtained from 8 major wheat-growing ...Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, is an important disease in China. To characterize the virulence and diversity of the pathogen, 1 082 isolates were obtained from 8 major wheat-growing regions during the spring growing season in 2011. The virulence test was performed by inoculation on detached leaves of 22 differential lines with known Pm genes. Frequencies of virulence on these genotypes ranged from 0 to 97.4%. None of the 1 082 isolates was compatible to Pm21 and less than 20.0%were virulent to the genotype carrying Pm13. In contrast, the virulence frequencies of each population was more than 50.0%to differentials carrying Pm1a, Pm3b, Pm3c, Pm3f, Pm5a, Pm6 and Pm8. In total, 1 028 pathotypes were detected, of which 984 were unique. Phenotypic diversity indices revealed a high level of diversity within populations. Genetic distance between different populations correlated signiifcantly with geographical distance （R2=0.494, P 0.001）. In addition, isolates from Xinjiang appear to form a separate group. Signiifcant positive or negative associations between alleles at pairs of virulence loci were detected in 57 allele pairs to Pm genes. Virulence and diversity of the 8 populations suggested that varieties with effective resistance gene combinations should be developed at a regional level.展开更多
Barley powdery mildew caused by Blumeria graminis f. sp. hordei （Bgh） is one of the most destructive foliar diseases of barley in the winter barley region of China. The evaluation and assessment of the virulence and...Barley powdery mildew caused by Blumeria graminis f. sp. hordei （Bgh） is one of the most destructive foliar diseases of barley in the winter barley region of China. The evaluation and assessment of the virulence and diversity of Bgh populations help to determine effective sources of resistance to the pathogen. 515 isolates were collected from seven populations of Bgh on cultivated barley in seven geographically distant locations in 2006. Their virulence was determined by inoculation onto 26 differential host lines. All of the isolates belonged to 58 pathotypes and 13 of which included 81% of these isolates. The most abundant pathotype was pathotype 0047 （18.3%）, the second most abundant was pathotype 0045 （11.8%） and the third most abundant was pathotype 0057 （7.8%）. Most of virulent genes investigated in this study showed similar frequencies in the seven different areas. These indicate that the seven locations may be in a uniform epidemiological region and barley cultivars in these areas may have similar genetic background. Diversities within these populations and distances between these populations measured by KOIND package were different. Correlations were not found between the genetic distance and the geographical distances between different locations. This suggested that long distance spread and local epidemics existed in the major winter barley growing regions in China.展开更多
To gain more precise information about molecular genetic variation for wild populations of Blumeria graminis f. sp. tritici from Qinghai Province, China, 38 single-colony isolates were purified from samples collected ...To gain more precise information about molecular genetic variation for wild populations of Blumeria graminis f. sp. tritici from Qinghai Province, China, 38 single-colony isolates were purified from samples collected from Haidong District, Xining City and Hainan Tibetan Autonomous Prefecture in 2010. The virulence of 21 isolates among them was tested at seedling stage on 34 wheat cultivars（lines） carrying known powdery mildew（Pm） resistant genes. The results showed that V1 a, V3 a, V3 c, V3 e, V5 a, V6, V7, V8 and V19 had high virulence frequencies（〉75%）, indicating a wide distribution; and V1 c, V5 b, V12, V13, V16, V21, VXBD, V2＋6, V2＋Mld and V4＋8, with less distribution, appeared to be lower in frequencies（0-20%）. The Nei＇s gene diversity（H）, Shannon＇s information index（I） and the percentage of polymorphic loci（P） were 0.23, 0.35 and 67.65%, respectively, which revealed a virulent diversity. The results from single nucleotide polymorphisms（SNPs） of 38 isolates showed that three housekeeping genes were found to contain a total of 9 SNP sites. 10 haplotypes（H1-H10） were inferred from the concatenated sequences, with 1 haplotype（H1） comprising of over 55% of Qinghai population. Phylogenic analysis did not show obvious geographical subdivision between the isolates. A multilocus haplotype network presented a radial structure, with H1 in the central as an inferred ancestor. Using analysis of molecular variance（AMOVA）, we found 1.63% of the total variation was among populations and 98.37% within populations, with a low fixations index（FST=0.01634, P〈0.05）. This revealed a relatively high genetic diversity but a low genetic divergence in Qinghai population. Moreover, the molecular data on gene flow（Nm=6.32） confirmed the migration of pathogen populations among areas in Qinghai Province.展开更多
Wheat stem rust, caused by Puccinia graminis f. sp. tritici(Pgt), is a potentially devastating fungal disease of wheat worldwide. The present study was to evaluate the resistance of 42 wheat monogenic lines with known...Wheat stem rust, caused by Puccinia graminis f. sp. tritici(Pgt), is a potentially devastating fungal disease of wheat worldwide. The present study was to evaluate the resistance of 42 wheat monogenic lines with known stem rust resistance(Sr) genes and 69 wheat cultivars to three new Pgt races(34C0MRGQM, 34C3MKGQM, and 34C6MTGSM)identified from aeciospores at the seedling and adult-plant stages. The phenotyping results revealed that monogenic lines harboring resistance genes Sr9e, Sr17, Sr21, Sr22, Sr26, Sr30, Sr31, Sr33, Sr35, Sr36, Sr37, Sr38, Sr47, SrTmp,and SrTt3 were effectively resistant to all three Pgt races at the seedling and adult-plant stages. In contrast, monogenic lines containing Sr5, Sr6, Sr7b, Sr9a, Sr9d, Sr9f, Sr9g, Sr9b, Sr16, Sr24, Sr28, and Sr39 were highly susceptible to these races at both seedling and adult-plant stages. The other lines with Sr8a, Sr10, Sr11, Sr13, Sr14, Sr15, Sr18, Sr20,Sr19, Sr23, Sr25, Sr27, Sr29, Sr32, and Sr34, displayed variable levels of resistance to one or two of the tested races.Seedling infection types(ITs) and adult-plant infection responses(IRs) indicated that 41(59.4%) of the wheat cultivars showed high resistance to all the three races. Molecular marker analysis showed that four wheat culitvars likely carried Sr2, 20 wheat culitvars likely carried Sr31, 9 wheat culitvars likely carried Sr38, and none of the cultivars carried Sr24,Sr25, and Sr26. Our results provide a scientific basis for rational utilization of the tested Sr genes and wheat cultivars against these novel Pgt races.展开更多
A high degree of virulence diversity has been maintained in the population of Puccinia graminis f. sp. tritici （Pgt） in northwestern United States. Although Berberis vulgaris is present in the region and Pgt has bee...A high degree of virulence diversity has been maintained in the population of Puccinia graminis f. sp. tritici （Pgt） in northwestern United States. Although Berberis vulgaris is present in the region and Pgt has been isolated from aecial infections on B. vulgaris, the population is too diverse to be explained by the limited presence of B. vulgaris alone. Since 2008, we have isolated P. graminis from aecial infections on fruits of Mahonia repens and Mahonia aquifolium from northwestern United States. These two native woody shrub species, widely distributed in western North America, were once classified as resistant to P. graminis based on artificial inoculations. By isolating P. graminis from aecia, we established that M. repens and M. aquifolium along with B. vulgaris （albeit infrequent） serve as the alternate hosts ofP. graminis in the region. The isolates of P. graminis from Mahonia of North America had diverse virulence patterns and most of the isolates could be differentiated on Morocco, Line E, Chinese Spring, Little Club, LMPG-6, Rusty, and other genotypes that are considered to be universally susceptible to most Pgt isolates. This discovery explained the persistence of virulence diversity of Pgt observed in isolates derived from uredinia on cereal crops in the region. In addition to cereal crops, uredinial stage of the P. graminis population is sustained by wild grasses, especially Elymus glaucus, a native grass sharing the same habitat with the rusted Mahonia spp. Although virulence to some important stem rust resistance genes was observed in some isolates derived from Mahonia of North America when tested against single stem rust resistance gene stocks, the overall virulence is very limited in these isolates. This is likely a result of limited selection pressure on the rust population. In contrast to northwestern United Sates, the Pgt population in east of the Rocky Mountains of North America has declined steadily with a single race, QFCSC, being predominant in the last decade. This decline is likely due to a combination of factors, of which a lack of sexual recombination in the region is perhaps the most important one.展开更多
Stem or black rust of wheat, caused by the fungus Puccinia graminis Pers. f. sp. tritici Eriks.＆E. Henn. （Pgt）, has historically caused severe losses to wheat （Triticum aestivum L.） production worldwide. In the F...Stem or black rust of wheat, caused by the fungus Puccinia graminis Pers. f. sp. tritici Eriks.＆E. Henn. （Pgt）, has historically caused severe losses to wheat （Triticum aestivum L.） production worldwide. In the Fujian and Guangdong provinces of China, six moderate-to-severe epidemics of wheat stem rust have occurred, which caused destructive losses of wheat between 1949 and 1966, although these were brought under control by integrated management. A rapid and reliable detection of the pathogen will contribute to the accurate forecast and seasonal control of this disease. The objective of this study was to develop a diagnostic molecular marker generated from simple sequence repeats （SSR） for the early rapid identiifcation of P. graminis. The genomic DNA of P. graminis, Puccinia striiformis, Puccinia triticina and seven other species was ampliifed by a pair of SSR primers generated by the FIASCO （fast isolation by AFLP sequences containing repeats） enrichment protocol. The primer set Pgtw （f）/Pgtw （r） generated a polymorphic pattern displaying a 330-bp DNA fragment speciifc for P. graminis whereas no DNA fragment was obtained from other non-target wheat fungal pathogens. The detection limit of the primer was 1 ng DNA in a 25-mL PCR reaction. The SSR markers of P. graminis can also be used to detect the presence of latent hyphae in Pgt-infected wheat leaves as early as 30 h post-inoculation. A rapid approach to distinguish P. graminis from similar pathogenic fungi would be anticipated in further study.展开更多
Simple sequence repeats （SSR） have been widely used as molecular markers due to their abundance and high polymorphism, However, up to now, the SSR markers had not been developed in the obligate biotrophic phytopatho...Simple sequence repeats （SSR） have been widely used as molecular markers due to their abundance and high polymorphism, However, up to now, the SSR markers had not been developed in the obligate biotrophic phytopathogenic fungus, Blumeria graminis f.sp. tritici. From （AC）10 and （AG）10 enriched genomic libraries for Bgt, 25 primer pairs were designed using the FIASCO （fast isolation by AFLP of sequences containing repeats） protocol. Five primer pairs exhibited polymorphism with allelic diversity from two to seven alleles and produced 29 alleles in a survey of 90 isolates collected from six provinces （cities） in China, while the others displayed monomorphic. Levels of observed heterozygosity ranged from 0.000-0.044 （mean 0.025） and expected heterozygosity ranged from 0.297-0.816 （mean 0.538）. These molecular markers provide a novel source to genetic diversity assays and to genetic and physical mapping ofBgt. SSR markers of Bgt need to be further explored.展开更多
Take-all is a serious disease found in wheat across the world. Haynaldia villosa is considered to be resistant to take-all at a high level. TH3 was an amphiploid （2n =42, AABBVV） between Triticum durum and Haynaldia...Take-all is a serious disease found in wheat across the world. Haynaldia villosa is considered to be resistant to take-all at a high level. TH3 was an amphiploid （2n =42, AABBVV） between Triticum durum and Haynaldia viUosa with significant resistance to take-all fungus isolated from China. In greenhouse experiment, the derivatives of the hybrid between wheat and TH3 showed better resistance to take-all than that of the wheat control. One of the derivatives named HW918-5 was selected for further analysis. Cytological and genomic in situ hybridization （GISH） analysis indicated that a monotelosome originated from H. villosa existed in the genome of the offspring of the line HW918-5. The monotelosome with promising resistant gene for take-all was located on the 3V chromosome of H. villosa in the further PCR-based molecular analysis.展开更多
Twenty isolated strains of Blumeria graminis f.sp. tritici collected from central Gansu province were studied with random amplified polymorphic DNA （RAPD） analysis. PCR amplifications using nine random primers gener...Twenty isolated strains of Blumeria graminis f.sp. tritici collected from central Gansu province were studied with random amplified polymorphic DNA （RAPD） analysis. PCR amplifications using nine random primers generated a total of 81 bands, of which, 54 were polymorphic. The total percentage of polymorphic bands varied from 50.0% to 88.9%. The average percentage based on RAPD patterns was approximately 66.7%, which indicated high heredity differentiation among isolates. Clustering analysis showed that the polymorphism of the twenty isolates was related to geographical origins but had little relationship with the physiological race.展开更多
Powdery mildew negatively impacts wheat yield and quality.Emmer wheat(Triticum dicoccum),an ancestral species of common wheat,is a gene donor for wheat improvement.Cultivated emmer accession H1-707 exhibited all-stage...Powdery mildew negatively impacts wheat yield and quality.Emmer wheat(Triticum dicoccum),an ancestral species of common wheat,is a gene donor for wheat improvement.Cultivated emmer accession H1-707 exhibited all-stage resistance to powdery mildew over consecutive years.Genetic analysis of H1-707 at the seedling stage revealed a dominant monogenic inheritance pattern,and the underlying gene was designated Pm71.By employing bulked segregant exome sequencing(BSE-Seq)and using 2000 F2:3 families,Pm71 was fine mapped to a 336-kb interval on chromosome arm 6AS by referencing to the durum cv.Svevo RefSeq 1.0.Collinearity analysis revealed high homology in the candidate interval between Svevo and six Triticum species.Among six high-confidence genes annotated within this interval,TRITD6Av1G005050 encoding a GDSL esterase/lipase was identified as a key candidate for Pm71.展开更多
Evaluation with the pot assay at seedling stage in greenhouse showed that oat (Arena saliva) was highly resistant to take-all disease to which, however, wheat (Triticum aestivum) was extremely susceptible. The oat roo...Evaluation with the pot assay at seedling stage in greenhouse showed that oat (Arena saliva) was highly resistant to take-all disease to which, however, wheat (Triticum aestivum) was extremely susceptible. The oat roots were shown to be inhibitory to the invasion and spread of take-all causing fungus G. graminis var. tritici by the following criteria: (i) less infection sites were observed (about 1/7 of those in wheat); (ii) the ectotrophic growth of G. graminis var. tritici on oat roots was much slower than that on those of wheat, and the runner hyphae appeared as kidney- or fork-shaped hyphopodia on the surface of oat roots which could not be discerned on that of wheat roots; (iii) the period from inoculation to penetration into the epidermis of oat roots was about 2.9 times as long as that of wheat; (iv) the infection hyphae were hindered substantially when it was about to penetrate into the epidermis of oat roots with the mycelium deformed; and (v) the cortical layer of oat roots was revealed to be展开更多
从药用植物一年蓬茎组织中分离并筛选获得了1株内生生防细菌EA19。经形态学、生理生化和16 S rRNA编码基因序列分析等实验,EA19与解淀粉芽孢杆菌(Bacillus amyloliquefaciens)亲缘关系最近。采用菌丝生长速率法对EA19进行了10种植物病...从药用植物一年蓬茎组织中分离并筛选获得了1株内生生防细菌EA19。经形态学、生理生化和16 S rRNA编码基因序列分析等实验,EA19与解淀粉芽孢杆菌(Bacillus amyloliquefaciens)亲缘关系最近。采用菌丝生长速率法对EA19进行了10种植物病原真菌的抑菌活性测定。结果表明,EA19菌体对稻梨孢、镰孢菌、胶孢炭疽菌、稻平脐蠕孢、立枯丝核菌、核盘菌、链格孢和青霉菌等植物病原真菌具有拮抗活性,对稻梨孢和核盘菌的抑制率分别达到96.99%±1.10%和99.16%±0.65%。EA19菌体对小麦白粉病菌(Blumeria graminis f.sp.tritici)的分生孢子萌发和吸器形成具有极显著的抑制作用(P<0.01),并导致病菌附着胞发育畸形。展开更多
Powdery mildew is a serious disease of wheat in China. As part of ITEC (International Triteace EST cooperation), EST (expressed sequence tags) technique was used to explore the gene expression in leaf induced by Ery...Powdery mildew is a serious disease of wheat in China. As part of ITEC (International Triteace EST cooperation), EST (expressed sequence tags) technique was used to explore the gene expression in leaf induced by Erysiphe graminis DC. A conventional cDNA library was constructed, and a total of 1 500 clones picked randomly from the library were sequenced, three hundred and eighty_seven ESTs of them were unique, which got the Accession Number in GenBank. About 49.4% ESTs showed significant similarity to functions of known sequences in GenBank. There are 196 ESTs' with functions not able to be determined, and eighty_four ESTs were demonstrated to be novel sequences. High_density dot membranes from unique clones were produced, and several disease resistance related genes were screened by differential hybridization.展开更多
Stripe rust and powdery mildew are both devastating diseases for durum and common wheat.Pyramiding of genes conferring resistance to one or more diseases in a single cultivar is an important breeding approach to provi...Stripe rust and powdery mildew are both devastating diseases for durum and common wheat.Pyramiding of genes conferring resistance to one or more diseases in a single cultivar is an important breeding approach to provide broader spectra of resistances in wheat improvement. A new powdery mildew resistance gene originating from wild emmer(Triticum turgidum var.dicoccoides) backcrossed into common wheat(T. aestivum) line WE35 was identified. It conferred an intermediate level of resistance to Blumeria graminis f. sp. tritici isolate E09 at the seedling stage and a high level of resistance at the adult plant stage. Genetic analysis showed that the powdery mildew resistance in WE35 was controlled by a dominant gene designated Pm64. Bulked segregant analysis(BSA) and molecular mapping indicated that Pm64 was located in chromosome bin 2 BL4-0.50–0.89. Polymorphic markers were developed from the corresponding genomic regions of Chinese Spring wheat and wild emmer accession Zavitan to delimit Pm64 to a 0.55 cM genetic interval between markers WGGBH1364 and WGGBH612, corresponding to a 15 Mb genomic region on Chinese Spring and Zavitan 2 BL, respectively. The genetic linkage map of Pm64 is critical for fine mapping and cloning. Pm64 was completely linked in repulsion with stripe rust resistance gene Yr5. Analysis of a larger segregating population might identify a recombinant line with both genes as a valuable resource in breeding for resistance to powdery mildew and stripe rust.展开更多
In China, a soil-borne virus causing a disease of winter wheat and associated with Polymyxa graminis, has been reported for many years and is now recognized as a new species, Chinese wheat mosaic virus(CWMV). Since th...In China, a soil-borne virus causing a disease of winter wheat and associated with Polymyxa graminis, has been reported for many years and is now recognized as a new species, Chinese wheat mosaic virus(CWMV). Since the determination of its genomic sequence, more progress has been made in understanding its genomic structure and functions. Molecular and serological methods have been developed to help survey the distribution of the virus and to provide the basic information needed for disease forecasting and control. At present, the best countermeasure is cultivation of resistant wheat varieties. In addition, development and application of some auxiliary countermeasures, such as rotation of non-host crops, delayed seed-sowing, reasonable application of nitrogen fertilizer, and treatment of imported seeds with fungicides before sowing, may be helpful for controlling the disease. The viral distribution and damage, virion properties, genome organization and spontaneous mutation, temperature sensitivity, and disease management options are here reviewed and/or discussed to help in developing more cost-effective countermeasures to control the disease in the future.展开更多
Wheat rusts continue to cause significant losses worldwide despite major efforts given to their genetic control. This is due to frequent evolution and selection of virulence in pathogen overcoming the deployed race-sp...Wheat rusts continue to cause significant losses worldwide despite major efforts given to their genetic control. This is due to frequent evolution and selection of virulence in pathogen overcoming the deployed race-specific resistance genes. Although the life of effective race-specific resistance genes can be prolonged by using gene combinations, an alternative approach being implemented at CIMMYT is to deploy varieties that posses adult plant resistance （APR） based on combinations of minor, slow rusting genes. When present alone, the APR genes do not confer adequate resistance especially under high disease pressure; however, combinations of 4 or 5 minor genes usually result in ＂near-immunity＂ or a high level of resistance. Although only a few APR genes are catalogued, various APR QTLs are now known and could lead to further characterization of additional genes. Four characterized genes have pleiotropic effects in conferring partial APR to all 3 rusts and powdery mildew, thus simplifying the task of breeding wheat varieties that are resistant to multiple diseases. Significant progress was made recently in developing high-yielding wheat germplasm that possesses high levels of APR to all three rusts by implementing a Mexico- Kenya shuttle breeding scheme. Parents with APR to Ug99 were hybridized with high-yielding parents that had adequate to high levels of APR to leaf rust and yellow rust. Segregating populations and advanced lines from these crosses were selected under high rust pressures in Mexico （leaf rust and yellow rust） and Kenya （Ug99 stem rust and yellow rust） to identify high- yielding progenies that possess high to adequate APR to all three rusts. International distribution of these high-yielding wheats is underway through CIMMYT intemational yield trials and screening nurseries. It is expected that several wheat varieties with APR to three rusts will be released and grown in various countries in the near-future that will allow determining the durability of resistance.展开更多
文摘[Objective] The research aimed to study the relationship between the hypersensitive response of wheat to Blumeria graminis f.sp.tritici and hydrogen peroxide,3 enzyme activities changes and lay the foundation for discussing the resistant physiological mechanism of wheat to B.graminis.[Method] Taking B.graminis Bgt 17 and Bgt 6 and wheat cultivar Yang 158 as test materials,the number of hypersensitive cells and activities of POD,PPO and SOD in wheat leaves treated by H2O2 were determined.[Result] The mastoid...
基金Supported by Starting Fund for Introduction of Qualified Personnel from Henan Agricultural University (30300190)~~
文摘This paper reviewed the research advances of Ug99 and its resistance breeding from the aspects of its discovery, race variation, pathogenicity, distribution, spread, exploration of relative resistant genes, linked molecular marker selection and resistance breeding strategies, to provide basis for comprehensive understanding of the new Puccinia graminis f. sp. tritici race Ug99 and its potential threat to wheat production. Ug99 is a new Puccinia grarninis f. sp. tritici race with high variability, strong pathogenicity and rapid spread speed, which is likely to cause global damages to world wheat production. We should strengthen the exploration and utilization of new resistance genes in wheat and relative species and breeding of new wheat varieties with durable resistance, to control and prevent damages caused by Ug99 and its variants.
基金supported by the National Basic Research Program of China (2013CB127700)the Special Fund for Agro-Scientific Research in the Public Interest, China (201303016)
文摘Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, is an important disease in China. To characterize the virulence and diversity of the pathogen, 1 082 isolates were obtained from 8 major wheat-growing regions during the spring growing season in 2011. The virulence test was performed by inoculation on detached leaves of 22 differential lines with known Pm genes. Frequencies of virulence on these genotypes ranged from 0 to 97.4%. None of the 1 082 isolates was compatible to Pm21 and less than 20.0%were virulent to the genotype carrying Pm13. In contrast, the virulence frequencies of each population was more than 50.0%to differentials carrying Pm1a, Pm3b, Pm3c, Pm3f, Pm5a, Pm6 and Pm8. In total, 1 028 pathotypes were detected, of which 984 were unique. Phenotypic diversity indices revealed a high level of diversity within populations. Genetic distance between different populations correlated signiifcantly with geographical distance （R2=0.494, P 0.001）. In addition, isolates from Xinjiang appear to form a separate group. Signiifcant positive or negative associations between alleles at pairs of virulence loci were detected in 57 allele pairs to Pm genes. Virulence and diversity of the 8 populations suggested that varieties with effective resistance gene combinations should be developed at a regional level.
基金support from the National Natural Science Foundation of China (30671289)the National Key Tech-nologies R&D Program (2006B BAD0 2B 04)+1 种基金the Nationnal Special Fund for Agro-Scientific Research inthe Public Interest (nyhyzx017-001-barley)the Ear-marked Fund for Modern Agro-Industry Technology Research System,China
文摘Barley powdery mildew caused by Blumeria graminis f. sp. hordei （Bgh） is one of the most destructive foliar diseases of barley in the winter barley region of China. The evaluation and assessment of the virulence and diversity of Bgh populations help to determine effective sources of resistance to the pathogen. 515 isolates were collected from seven populations of Bgh on cultivated barley in seven geographically distant locations in 2006. Their virulence was determined by inoculation onto 26 differential host lines. All of the isolates belonged to 58 pathotypes and 13 of which included 81% of these isolates. The most abundant pathotype was pathotype 0047 （18.3%）, the second most abundant was pathotype 0045 （11.8%） and the third most abundant was pathotype 0057 （7.8%）. Most of virulent genes investigated in this study showed similar frequencies in the seven different areas. These indicate that the seven locations may be in a uniform epidemiological region and barley cultivars in these areas may have similar genetic background. Diversities within these populations and distances between these populations measured by KOIND package were different. Correlations were not found between the genetic distance and the geographical distances between different locations. This suggested that long distance spread and local epidemics existed in the major winter barley growing regions in China.
基金supported by the National Basic Research Program of China(2011CB100403 and 2013CB127704)the Special Fund for Agro-Scientific Research in the Public Interest,China(201303016)
文摘To gain more precise information about molecular genetic variation for wild populations of Blumeria graminis f. sp. tritici from Qinghai Province, China, 38 single-colony isolates were purified from samples collected from Haidong District, Xining City and Hainan Tibetan Autonomous Prefecture in 2010. The virulence of 21 isolates among them was tested at seedling stage on 34 wheat cultivars（lines） carrying known powdery mildew（Pm） resistant genes. The results showed that V1 a, V3 a, V3 c, V3 e, V5 a, V6, V7, V8 and V19 had high virulence frequencies（〉75%）, indicating a wide distribution; and V1 c, V5 b, V12, V13, V16, V21, VXBD, V2＋6, V2＋Mld and V4＋8, with less distribution, appeared to be lower in frequencies（0-20%）. The Nei＇s gene diversity（H）, Shannon＇s information index（I） and the percentage of polymorphic loci（P） were 0.23, 0.35 and 67.65%, respectively, which revealed a virulent diversity. The results from single nucleotide polymorphisms（SNPs） of 38 isolates showed that three housekeeping genes were found to contain a total of 9 SNP sites. 10 haplotypes（H1-H10） were inferred from the concatenated sequences, with 1 haplotype（H1） comprising of over 55% of Qinghai population. Phylogenic analysis did not show obvious geographical subdivision between the isolates. A multilocus haplotype network presented a radial structure, with H1 in the central as an inferred ancestor. Using analysis of molecular variance（AMOVA）, we found 1.63% of the total variation was among populations and 98.37% within populations, with a low fixations index（FST=0.01634, P〈0.05）. This revealed a relatively high genetic diversity but a low genetic divergence in Qinghai population. Moreover, the molecular data on gene flow（Nm=6.32） confirmed the migration of pathogen populations among areas in Qinghai Province.
文摘Wheat stem rust, caused by Puccinia graminis f. sp. tritici(Pgt), is a potentially devastating fungal disease of wheat worldwide. The present study was to evaluate the resistance of 42 wheat monogenic lines with known stem rust resistance(Sr) genes and 69 wheat cultivars to three new Pgt races(34C0MRGQM, 34C3MKGQM, and 34C6MTGSM)identified from aeciospores at the seedling and adult-plant stages. The phenotyping results revealed that monogenic lines harboring resistance genes Sr9e, Sr17, Sr21, Sr22, Sr26, Sr30, Sr31, Sr33, Sr35, Sr36, Sr37, Sr38, Sr47, SrTmp,and SrTt3 were effectively resistant to all three Pgt races at the seedling and adult-plant stages. In contrast, monogenic lines containing Sr5, Sr6, Sr7b, Sr9a, Sr9d, Sr9f, Sr9g, Sr9b, Sr16, Sr24, Sr28, and Sr39 were highly susceptible to these races at both seedling and adult-plant stages. The other lines with Sr8a, Sr10, Sr11, Sr13, Sr14, Sr15, Sr18, Sr20,Sr19, Sr23, Sr25, Sr27, Sr29, Sr32, and Sr34, displayed variable levels of resistance to one or two of the tested races.Seedling infection types(ITs) and adult-plant infection responses(IRs) indicated that 41(59.4%) of the wheat cultivars showed high resistance to all the three races. Molecular marker analysis showed that four wheat culitvars likely carried Sr2, 20 wheat culitvars likely carried Sr31, 9 wheat culitvars likely carried Sr38, and none of the cultivars carried Sr24,Sr25, and Sr26. Our results provide a scientific basis for rational utilization of the tested Sr genes and wheat cultivars against these novel Pgt races.
文摘A high degree of virulence diversity has been maintained in the population of Puccinia graminis f. sp. tritici （Pgt） in northwestern United States. Although Berberis vulgaris is present in the region and Pgt has been isolated from aecial infections on B. vulgaris, the population is too diverse to be explained by the limited presence of B. vulgaris alone. Since 2008, we have isolated P. graminis from aecial infections on fruits of Mahonia repens and Mahonia aquifolium from northwestern United States. These two native woody shrub species, widely distributed in western North America, were once classified as resistant to P. graminis based on artificial inoculations. By isolating P. graminis from aecia, we established that M. repens and M. aquifolium along with B. vulgaris （albeit infrequent） serve as the alternate hosts ofP. graminis in the region. The isolates of P. graminis from Mahonia of North America had diverse virulence patterns and most of the isolates could be differentiated on Morocco, Line E, Chinese Spring, Little Club, LMPG-6, Rusty, and other genotypes that are considered to be universally susceptible to most Pgt isolates. This discovery explained the persistence of virulence diversity of Pgt observed in isolates derived from uredinia on cereal crops in the region. In addition to cereal crops, uredinial stage of the P. graminis population is sustained by wild grasses, especially Elymus glaucus, a native grass sharing the same habitat with the rusted Mahonia spp. Although virulence to some important stem rust resistance genes was observed in some isolates derived from Mahonia of North America when tested against single stem rust resistance gene stocks, the overall virulence is very limited in these isolates. This is likely a result of limited selection pressure on the rust population. In contrast to northwestern United Sates, the Pgt population in east of the Rocky Mountains of North America has declined steadily with a single race, QFCSC, being predominant in the last decade. This decline is likely due to a combination of factors, of which a lack of sexual recombination in the region is perhaps the most important one.
基金Financial supports by the National 973 Program of China (2013CB127701 and 2011CB100403)the Ntional 863 Program of China (2012AA101501)+3 种基金the National Key Technologies Research and Development Program of China (2012BAD19BA04) from the Ministry of Science and Technology of Chinathe Special Fund for Agro-Scientific Research in the Public Interest, China (200903035)the China Agriculture Research System (CARS-03) from the Ministry of Agriculture of Chinathe National Natural Scientific Foundation of China (31371884)
文摘Stem or black rust of wheat, caused by the fungus Puccinia graminis Pers. f. sp. tritici Eriks.＆E. Henn. （Pgt）, has historically caused severe losses to wheat （Triticum aestivum L.） production worldwide. In the Fujian and Guangdong provinces of China, six moderate-to-severe epidemics of wheat stem rust have occurred, which caused destructive losses of wheat between 1949 and 1966, although these were brought under control by integrated management. A rapid and reliable detection of the pathogen will contribute to the accurate forecast and seasonal control of this disease. The objective of this study was to develop a diagnostic molecular marker generated from simple sequence repeats （SSR） for the early rapid identiifcation of P. graminis. The genomic DNA of P. graminis, Puccinia striiformis, Puccinia triticina and seven other species was ampliifed by a pair of SSR primers generated by the FIASCO （fast isolation by AFLP sequences containing repeats） enrichment protocol. The primer set Pgtw （f）/Pgtw （r） generated a polymorphic pattern displaying a 330-bp DNA fragment speciifc for P. graminis whereas no DNA fragment was obtained from other non-target wheat fungal pathogens. The detection limit of the primer was 1 ng DNA in a 25-mL PCR reaction. The SSR markers of P. graminis can also be used to detect the presence of latent hyphae in Pgt-infected wheat leaves as early as 30 h post-inoculation. A rapid approach to distinguish P. graminis from similar pathogenic fungi would be anticipated in further study.
基金supported by the National Basic Research Program of China(2006CB100203 and 2011CB100403)the Key Technologies R&D Program of China during the 11th Five-Year Plan period(2006BAD08A05)the Special Fund for Agro-Scientific Research in the Public Interest(3-15),China
文摘Simple sequence repeats （SSR） have been widely used as molecular markers due to their abundance and high polymorphism, However, up to now, the SSR markers had not been developed in the obligate biotrophic phytopathogenic fungus, Blumeria graminis f.sp. tritici. From （AC）10 and （AG）10 enriched genomic libraries for Bgt, 25 primer pairs were designed using the FIASCO （fast isolation by AFLP of sequences containing repeats） protocol. Five primer pairs exhibited polymorphism with allelic diversity from two to seven alleles and produced 29 alleles in a survey of 90 isolates collected from six provinces （cities） in China, while the others displayed monomorphic. Levels of observed heterozygosity ranged from 0.000-0.044 （mean 0.025） and expected heterozygosity ranged from 0.297-0.816 （mean 0.538）. These molecular markers provide a novel source to genetic diversity assays and to genetic and physical mapping ofBgt. SSR markers of Bgt need to be further explored.
文摘Take-all is a serious disease found in wheat across the world. Haynaldia villosa is considered to be resistant to take-all at a high level. TH3 was an amphiploid （2n =42, AABBVV） between Triticum durum and Haynaldia viUosa with significant resistance to take-all fungus isolated from China. In greenhouse experiment, the derivatives of the hybrid between wheat and TH3 showed better resistance to take-all than that of the wheat control. One of the derivatives named HW918-5 was selected for further analysis. Cytological and genomic in situ hybridization （GISH） analysis indicated that a monotelosome originated from H. villosa existed in the genome of the offspring of the line HW918-5. The monotelosome with promising resistant gene for take-all was located on the 3V chromosome of H. villosa in the further PCR-based molecular analysis.
文摘Twenty isolated strains of Blumeria graminis f.sp. tritici collected from central Gansu province were studied with random amplified polymorphic DNA （RAPD） analysis. PCR amplifications using nine random primers generated a total of 81 bands, of which, 54 were polymorphic. The total percentage of polymorphic bands varied from 50.0% to 88.9%. The average percentage based on RAPD patterns was approximately 66.7%, which indicated high heredity differentiation among isolates. Clustering analysis showed that the polymorphism of the twenty isolates was related to geographical origins but had little relationship with the physiological race.
基金financially supported by National Natural Science Foundation of China(32301800,32301923 and 32072053)Wheat Industrial Technology System of Shandong Province(SDAIT-01-01)Key Research and Development Project of Shandong Province(2022LZG002-4,2023LZGC009-4-4).
文摘Powdery mildew negatively impacts wheat yield and quality.Emmer wheat(Triticum dicoccum),an ancestral species of common wheat,is a gene donor for wheat improvement.Cultivated emmer accession H1-707 exhibited all-stage resistance to powdery mildew over consecutive years.Genetic analysis of H1-707 at the seedling stage revealed a dominant monogenic inheritance pattern,and the underlying gene was designated Pm71.By employing bulked segregant exome sequencing(BSE-Seq)and using 2000 F2:3 families,Pm71 was fine mapped to a 336-kb interval on chromosome arm 6AS by referencing to the durum cv.Svevo RefSeq 1.0.Collinearity analysis revealed high homology in the candidate interval between Svevo and six Triticum species.Among six high-confidence genes annotated within this interval,TRITD6Av1G005050 encoding a GDSL esterase/lipase was identified as a key candidate for Pm71.
基金This work was supported by theShaanxi Provincial Scientific Research Project (Grant No. 39725033) and the Postdoctoral Science Foundation of China (Grant No. 0208171304) and the Subject Constructional Foundation of Nanjing University (Grant No. 020
文摘Evaluation with the pot assay at seedling stage in greenhouse showed that oat (Arena saliva) was highly resistant to take-all disease to which, however, wheat (Triticum aestivum) was extremely susceptible. The oat roots were shown to be inhibitory to the invasion and spread of take-all causing fungus G. graminis var. tritici by the following criteria: (i) less infection sites were observed (about 1/7 of those in wheat); (ii) the ectotrophic growth of G. graminis var. tritici on oat roots was much slower than that on those of wheat, and the runner hyphae appeared as kidney- or fork-shaped hyphopodia on the surface of oat roots which could not be discerned on that of wheat roots; (iii) the period from inoculation to penetration into the epidermis of oat roots was about 2.9 times as long as that of wheat; (iv) the infection hyphae were hindered substantially when it was about to penetrate into the epidermis of oat roots with the mycelium deformed; and (v) the cortical layer of oat roots was revealed to be
文摘Powdery mildew is a serious disease of wheat in China. As part of ITEC (International Triteace EST cooperation), EST (expressed sequence tags) technique was used to explore the gene expression in leaf induced by Erysiphe graminis DC. A conventional cDNA library was constructed, and a total of 1 500 clones picked randomly from the library were sequenced, three hundred and eighty_seven ESTs of them were unique, which got the Accession Number in GenBank. About 49.4% ESTs showed significant similarity to functions of known sequences in GenBank. There are 196 ESTs' with functions not able to be determined, and eighty_four ESTs were demonstrated to be novel sequences. High_density dot membranes from unique clones were produced, and several disease resistance related genes were screened by differential hybridization.
基金supported by the National Key Research and Development Program of China (2017YFD0101004)the Science and Technology Service Network Initiative of Chinese Academy of Sciences (KFJ-STS-ZDTP-024)
文摘Stripe rust and powdery mildew are both devastating diseases for durum and common wheat.Pyramiding of genes conferring resistance to one or more diseases in a single cultivar is an important breeding approach to provide broader spectra of resistances in wheat improvement. A new powdery mildew resistance gene originating from wild emmer(Triticum turgidum var.dicoccoides) backcrossed into common wheat(T. aestivum) line WE35 was identified. It conferred an intermediate level of resistance to Blumeria graminis f. sp. tritici isolate E09 at the seedling stage and a high level of resistance at the adult plant stage. Genetic analysis showed that the powdery mildew resistance in WE35 was controlled by a dominant gene designated Pm64. Bulked segregant analysis(BSA) and molecular mapping indicated that Pm64 was located in chromosome bin 2 BL4-0.50–0.89. Polymorphic markers were developed from the corresponding genomic regions of Chinese Spring wheat and wild emmer accession Zavitan to delimit Pm64 to a 0.55 cM genetic interval between markers WGGBH1364 and WGGBH612, corresponding to a 15 Mb genomic region on Chinese Spring and Zavitan 2 BL, respectively. The genetic linkage map of Pm64 is critical for fine mapping and cloning. Pm64 was completely linked in repulsion with stripe rust resistance gene Yr5. Analysis of a larger segregating population might identify a recombinant line with both genes as a valuable resource in breeding for resistance to powdery mildew and stripe rust.
基金funded by the National Natural Science Foundation of China(31501604 and 31601603)the Project of New Varieties of Genetically Modified Wheat of China(2016ZX08002001)+2 种基金the Special Fund for Agro-scientific Research in the Public Interest of China(201303021)the earmarked fund for China Agriculture Research System(CARS-3-1)the State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control,China(2010DS700124-KF1512 and 2010DS700124-KF1607)
文摘In China, a soil-borne virus causing a disease of winter wheat and associated with Polymyxa graminis, has been reported for many years and is now recognized as a new species, Chinese wheat mosaic virus(CWMV). Since the determination of its genomic sequence, more progress has been made in understanding its genomic structure and functions. Molecular and serological methods have been developed to help survey the distribution of the virus and to provide the basic information needed for disease forecasting and control. At present, the best countermeasure is cultivation of resistant wheat varieties. In addition, development and application of some auxiliary countermeasures, such as rotation of non-host crops, delayed seed-sowing, reasonable application of nitrogen fertilizer, and treatment of imported seeds with fungicides before sowing, may be helpful for controlling the disease. The viral distribution and damage, virion properties, genome organization and spontaneous mutation, temperature sensitivity, and disease management options are here reviewed and/or discussed to help in developing more cost-effective countermeasures to control the disease in the future.
基金financial resources from the Durable Rust Resistant Wheat Project led by Cornell University,USAsupported by the Bill & Melinda Gates Foundation+6 种基金ICAR-IndiaUSDA-ARS and USAID,USAGRDC AustraliaAgrovegetal-Spainthe Northwestern Mexican Farmer Association (Patronato) and CONFUPRO,MexicoSDC,SwitzerlandCIMMYT and INIFAP
文摘Wheat rusts continue to cause significant losses worldwide despite major efforts given to their genetic control. This is due to frequent evolution and selection of virulence in pathogen overcoming the deployed race-specific resistance genes. Although the life of effective race-specific resistance genes can be prolonged by using gene combinations, an alternative approach being implemented at CIMMYT is to deploy varieties that posses adult plant resistance （APR） based on combinations of minor, slow rusting genes. When present alone, the APR genes do not confer adequate resistance especially under high disease pressure; however, combinations of 4 or 5 minor genes usually result in ＂near-immunity＂ or a high level of resistance. Although only a few APR genes are catalogued, various APR QTLs are now known and could lead to further characterization of additional genes. Four characterized genes have pleiotropic effects in conferring partial APR to all 3 rusts and powdery mildew, thus simplifying the task of breeding wheat varieties that are resistant to multiple diseases. Significant progress was made recently in developing high-yielding wheat germplasm that possesses high levels of APR to all three rusts by implementing a Mexico- Kenya shuttle breeding scheme. Parents with APR to Ug99 were hybridized with high-yielding parents that had adequate to high levels of APR to leaf rust and yellow rust. Segregating populations and advanced lines from these crosses were selected under high rust pressures in Mexico （leaf rust and yellow rust） and Kenya （Ug99 stem rust and yellow rust） to identify high- yielding progenies that possess high to adequate APR to all three rusts. International distribution of these high-yielding wheats is underway through CIMMYT intemational yield trials and screening nurseries. It is expected that several wheat varieties with APR to three rusts will be released and grown in various countries in the near-future that will allow determining the durability of resistance.
