title: Identification of molecular markers associated with Verticillium wilt resistance in alfalfa (Medicago sativa L.) using high-resolution melting.
abstract: Verticillium wilt, caused by the soilborne fungus, Verticillium alfalfae, is one of the most serious diseases of alfalfa (Medicago sativa L.) worldwide. To identify loci associated with resistance to Verticillium wilt, a bulk segregant analysis was conducted in susceptible or resistant pools constructed from 13 synthetic alfalfa populations, followed by association mapping in two F1 populations consisted of 352 individuals. Simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers were used for genotyping. Phenotyping was done by manual inoculation of the pathogen to replicated cloned plants of each individual and disease severity was scored using a standard scale. Marker-trait association was analyzed by TASSEL. Seventeen SNP markers significantly associated with Verticillium wilt resistance were identified and they were located on chromosomes 1, 2, 4, 7 and 8. SNP markers identified on chromosomes 2, 4 and 7 co-locate with regions of Verticillium wilt resistance loci reported in M. truncatula. Additional markers identified on chromosomes 1 and 8 located the regions where no Verticillium resistance locus has been reported. This study highlights the value of SNP genotyping by high resolution melting to identify the disease resistance loci in tetraploid alfalfa. With further validation, the markers identified in this study could be used for improving resistance to Verticillium wilt in alfalfa breeding programs.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Plant Germplasm Introduction and Testing Research, 24106 N Bunn Road, Prosser, Washington, United States of America.
authors.forename: Tiejun
authors.initials: T
authors.lastname: Zhang
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Plant Germplasm Introduction and Testing Research, 24106 N Bunn Road, Prosser, Washington, United States of America.
authors.forename: Long-Xi
authors.initials: LX
authors.lastname: Yu
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Plant Germplasm Introduction and Testing Research, 24106 N Bunn Road, Prosser, Washington, United States of America.
authors.forename: Per
authors.initials: P
authors.lastname: McCord
authors.affiliation: DuPont Pioneer, W8131 State HWY 60, Arlington, Wisconsin, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Miller
authors.affiliation: DuPont Pioneer, W8131 State HWY 60, Arlington, Wisconsin, United States of America.
authors.forename: Suresh
authors.initials: S
authors.lastname: Bhamidimarri
authors.affiliation: Alforex Seeds, N4505 CTH M, West Salem, Wisconsin, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Johnson
authors.affiliation: Forage Improvement Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, Oklahoma, United States of America.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Monteros
authors.affiliation: Forage Genetics International, Inc. 7661 Becker Road, Davis, California, United States of America.
authors.forename: Julie
authors.initials: J
authors.lastname: Ho
authors.affiliation: Forage Genetics International, Inc. 7661 Becker Road, Davis, California, United States of America.
authors.forename: Peter
authors.initials: P
authors.lastname: Reisen
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, 495 Borlaug Hall, 1991 Upper Buford Circle, Saint Paul, Minnesota, United States of America.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Samac
mesh_terms: D005838:Genotype; D000455:Medicago sativa / Q000235:genetics* / Q000382:microbiology*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D020641:Polymorphism, Single Nucleotide; D020172:Verticillium / Q000502:physiology*