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ARS Home » Pacific West Area » Pullman, Washington » Plant Germplasm Introduction and Testing Research » Research » Publications at this Location » Publication #324404

Title: Genotyping-by-sequencing based genome-wide association studies on Verticillium wilt resistance in heterozygous autotetraploid alfalfa (Medicago sativa L.)

item Yu, Long-Xi
item ZHENG, PINGI - Washington State University
item ZHANG, TIEJUN - Chinese Academy Of Agricultural Sciences
item RODRIGUEZ, JONAS - Forage Genetics International
item MAIN, DORRIE - Washington State University

Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/29/2016
Publication Date: 3/2/2016
Citation: Yu, L., Zheng, P., Zhang, T., Rodriguez, J., Main, D. 2016. Genotyping-by-sequencing based genome-wide association studies on Verticillium wilt resistance in heterozygous autotetraploid alfalfa (Medicago sativa L.). Molecular Plant Pathology. 18(2):187-194.

Interpretive Summary: USDA-ARS and alfalfa seed companies agreed on a joint effort to identify publically available markers for selection for resistance to Verticillium wilt in alfalfa. Forage Genetics International generated and phenotyped alfalfa populations of 179 individuals. We genotyped individuals using next generation sequencing technology. We performed genome-wide association studies and identified a group of molecular markers significantly associated with Verticillium wilt resistance. The markers identified in this study could be used for maeker-assisted selection to improve alfalfa resistance to Verticillium wilt.

Technical Abstract: Verticillium wilt (VW) is a fungal disease which causes severe yield loss in alfalfa. The most effective method to control the disease is through the development and use of resistant varieties. Identification of gene loci linked to VW resistance will facilitate breeding for the disease-resistant alfalfa. In the present investigation, we applied an integrated framework of genome-wide association with high-throughput genotyping by sequencing for identifying VW resistance loci in a panel of alfalfa breeding populations developed for the disease resistance. Phenotyping was done by manual inoculation of the pathogen to replicated cloned plants of each individual and scored for the disease resistance using the standard protocol. Marker-trait association by linkage disequilibrium identified 10 GBS markers significantly associated with VW resistance. Alignment of the sequence tags to the M. truncatula genome revealed multiple chromosomal locations of significant markers. Three, two, one and five markers were located on chromosomes 5, 6, 7 and 8, respectively. Co-localizations of the resistance loci were found on chromosomes 7 and 8 between our previous report and the present study. BLAST search using the flanking sequences of the resistance loci against M. truncatula genome identified putative candidate genes with potential function in disease resistance. With further investigation, these markers may be used for marker-assisted selection for breeding VW resistant alfalfa.