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Research Project: Biochemical Technologies to Enable the Commercial Production of Biofuels from Lignocellulosic Biomass

Location: Bioenergy Research

Title: Virulence structure of Blumeria graminis f.sp. tritici and its genetic diversity by ISSR and SRAP profiling analyses

Author
item LIU, NA - Sichuan Agricultural University
item Liu, Zonglin
item GUOSHU, GONG - Sichuan Agricultural University
item ZHANG, MIN - Sichuan Agricultural University
item WANG, XU - Sichuan Agricultural University
item ZHOU, YOU - Sichuan Agricultural University
item QI, XIAOBO - Sichuan Agricultural University
item CHEN, HUABOA - Sichuan Agricultural University
item YANG, JIZHI - Sichuan Agricultural University
item LUO, PEIGAO - Sichuan Agricultural University
item YANG, CHUNPING - Sichuan Agricultural University

Submitted to: PLoS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2015
Publication Date: 6/22/2015
Publication URL: http://handle.nal.usda.gov/10113/62262
Citation: Liu, N., Liu, Z., Guoshu, G., Zhang, M., Wang, X., Zhou, Y., Qi, X., Chen, H., Yang, J., Luo, P., Yang, C. 2015. Virulence structure of Blumeria graminis f.sp. tritici and its genetic diversity by ISSR and SRAP profiling analyses. PLoS One. DOI: 10.1371/journal.pone.0130881.

Interpretive Summary: Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most destructive wheat diseases distributed worldwide and the obligate biotrophic pathogen is able to rapidly adapt to resistant cultivars. For an efficient disease resistance breeding program, it is essential to understand virulence frequency of the pathogen in order to identify the source of resistant genes. Conventional evaluation methods using wheat cultivars are helpful in identification of prevalent virulence genes but limited in detection of the genetic background that mediates the virulence of the pathogen. Understanding genetic diversity of wheat powdery mildew with reliable molecular evidence is needed. In this research, ARS scientist in collaboration with scientists from China investigated the population structure of the pathogen and characterized population genetics of the pathogen in Sichuan Province, China using molecular methods. This research identified high virulence and low virulence groups with true resistance genes and found many previously identified resistance genes lost their resistance functions. Applying informative molecular biology methods of inter-simple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) polymorphic allele analyses, this research found that both ISSR and SRAP allele profiling analyses detected significantly high levels of genetic diversity for powdery mildew populations in Sichuan. ISSR and SRAP alleles were more efficient in characterization of smaller or more closely related populations than distantly related populations. These results demonstrated an effective means to monitor population diversity using molecular tools. The findings in this study provide the most updated virulence structure and population diversity for the pathogen, which will aid in the development of an efficient disease resistance breeding program.

Technical Abstract: Blumeria graminis f. sp. tritici is an obligate biotrophic pathogen causing wheat powdery mildew that has a great genetic flexibility and variations in relationship to its host plant. Application of disease resistant cultivars is an essential disease management measurement. Due to its rapid adaptation in overcoming plant resistance on a gene-to-gene basis, monitoring virulence structure and genetic variations of pathogenic populations are necessary for an effective disease resistance breeding program. This study investigated 17 pathogenic populations in Sichuan, China and classified 109 isolates into two distinguished groups of HV (high virulence, 92 isolates) and LV (low virulence, 17 isolates) groups. A relatively lower frequency of virulence gene was found in populations of Yibin (South region), Xichang (West region), and Meishan (Middle region). Many previously known resistant genes were found to lose resistance and only Pm13, Pm5b, Pm2+6, and PmXBD remained their resistant function. Resistance gene Pm21 displayed an immune response to pathogenic challenges against all populations in Sichuan. Our AMOVA analysis revealed significantly higher levels of variation within populations and lower levels of variation among populations within regions. A relatively higher level of gene flow was also detected among populations for the four regions. Cluster analyses applying informative ISSR and SRAP polymorphic alleles distinguished closely related populations within each region. While similar members were grouped together by both ISSR and SRAP matrix, SRAP alleles were distinct from the ISSR markers. Both ISSR and SRAP allele profiling analyses signified high levels of genetic diversity for powdery mildew populations in Sichuan. We did not observe a significant association of these alleles with the virulence or pathogenicity of the pathogen. It appeared that ISSR and SRAP alleles were more efficient in characterization of smaller or more closely related populations than distantly related populations.