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Mt QRRS 1 , an R ‐locus required for Medicago truncatula quantitative resistance to Ralstonia solanacearum
Author(s) -
Ben Cécile,
Debellé Frédéric,
Berges Hélène,
Bellec Arnaud,
Jardinaud MarieFrançoise,
Anson Philippe,
Huguet Thierry,
Gentzbittel Laurent,
Vailleau Fabienne
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12299
Subject(s) - ralstonia solanacearum , biology , quantitative trait locus , medicago truncatula , locus (genetics) , genetics , candidate gene , bacterial wilt , gene , plant disease resistance , bacterial artificial chromosome , inbred strain , botany , pathogen , bacteria , symbiosis , genome
SummaryRalstonia solanacearum is a major soilborne pathogen that attacks > 200 plant species, including major crops. To characterize Mt QRRS 1 , a major quantitative trait locus ( QTL ) for resistance towards this bacterium in the model legume Medicago truncatula , genetic and functional approaches were combined. QTL analyses together with disease scoring of heterogeneous inbred families were used to define the locus. The candidate region was studied by physical mapping using a bacterial artificial chromosome ( BAC ) library of the resistant line, and sequencing. In planta bacterial growth measurements, grafting experiments and gene expression analysis were performed to investigate the mechanisms by which this locus confers resistance to R. solanacearum . The Mt QRRS 1 locus was localized to the same position in two recombinant inbred line populations and was narrowed down to a 64 kb region. Comparison of parental line sequences revealed 15 candidate genes with sequence polymorphisms, but no evidence of differential gene expression upon infection. A role for the hypocotyl in resistance establishment was shown. These data indicate that the quantitative resistance to bacterial wilt conferred by Mt QRRS 1 , which contains a cluster of seven R genes, is shared by different accessions and may act through intralocus interactions to promote resistance.