Genetic and physical mapping of candidate genes for resistance to Fusarium oxysporum f.sp. tracheiphilum race 3 in cowpea [Vigna unguiculata (L.) Walp]

PLoS One. 2012;7(7):e41600. doi: 10.1371/journal.pone.0041600. Epub 2012 Jul 31.

Abstract

Fusarium oxysporum f.sp. tracheiphilum (Fot) is a soil-borne fungal pathogen that causes vascular wilt disease in cowpea. Fot race 3 is one of the major pathogens affecting cowpea production in California. Identification of Fot race 3 resistance determinants will expedite delivery of improved cultivars by replacing time-consuming phenotypic screening with selection based on perfect markers, thereby generating successful cultivars in a shorter time period. Resistance to Fot race 3 was studied in the RIL population California Blackeye 27 (resistant) x 24-125B-1 (susceptible). Biparental mapping identified a Fot race 3 resistance locus, Fot3-1, which spanned 3.56 cM on linkage group one of the CB27 x 24-125B-1 genetic map. A marker-trait association narrowed the resistance locus to a 1.2 cM region and identified SNP marker 1_1107 as co-segregating with Fot3-1 resistance. Macro and microsynteny was observed for the Fot3-1 locus region in Glycine max where six disease resistance genes were observed in the two syntenic regions of soybean chromosomes 9 and 15. Fot3-1 was identified on the cowpea physical map on BAC clone CH093L18, spanning approximately 208,868 bp on BAC contig250. The Fot3-1 locus was narrowed to 0.5 cM distance on the cowpea genetic map linkage group 6, flanked by SNP markers 1_0860 and 1_1107. BAC clone CH093L18 was sequenced and four cowpea sequences with similarity to leucine-rich repeat serine/threonine protein kinases were identified and are cowpea candidate genes for the Fot3-1 locus. This study has shown how readily candidate genes can be identified for simply inherited agronomic traits when appropriate genetic stocks and integrated genomic resources are available. High co-linearity between cowpea and soybean genomes illustrated that utilizing synteny can transfer knowledge from a reference legume to legumes with less complete genomic resources. Identification of Fot race 3 resistance genes will enable transfer into high yielding cowpea varieties using marker-assisted selection (MAS).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Breeding
  • Chromosome Mapping*
  • Chromosomes, Artificial, Bacterial / genetics
  • Chromosomes, Plant
  • Contig Mapping
  • Disease Resistance / genetics*
  • Fabaceae / genetics*
  • Fabaceae / immunology
  • Fabaceae / microbiology
  • Fusarium / immunology*
  • Genes, Plant
  • Genetic Markers
  • Molecular Sequence Annotation
  • Phenotype
  • Plant Diseases / microbiology*
  • Polymorphism, Single Nucleotide
  • Synteny

Substances

  • Genetic Markers

Grants and funding

This work was supported in part by the Generation Challenge Program through a grant from the Bill and Melinda Gates Foundation, the U.S. Agency for International Development Collaborative Research Support Program Grants GDG-G-00-02-00012-00 and EDH-A-00-07-00005 and the University of California Agricultural Experiment Station. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.