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The Plant Genome Abstract - Original Research

Identification of a Candidate Gene in Solanum habrochaites for Resistance to a Race 1 Strain of Pseudomonas syringae pv. tomato


This article in TPG

  1. Vol. 8 No. 3
    unlockOPEN ACCESS
    Received: Feb 13, 2015
    Accepted: Sept 01, 2015
    Published: November 6, 2015

    * Corresponding author(s): gbm7@cornell.edu
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  1. Zhilong Baoa,
  2. Fanhong Menga,
  3. Susan R. Stricklera,
  4. Diane M. Dunhama,
  5. Kathy R. Munkvolda and
  6. Gregory B. Martin *ab
  1. a Boyce Thompson Institute for Plant Research, Ithaca, NY 14853
    b Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell Univ., Ithaca, NY 14853


Bacterial speck disease caused by Pseudomonas syringae pv. tomato (Pst) is a persistent problem on tomato (Solanum lycopersicum L.). Resistance against race 0 Pst strains is conferred by the Pto protein, which recognizes either of two pathogen effectors: AvrPto or AvrPtoB. However, current tomato varieties do not have resistance to the increasingly common race 1 strains, which lack these effectors. We identified accessions of Solanum habrochaites S. Knapp & D. M. Spooner that are resistant to the race 1 strain T1. Genome sequence comparisons of T1 and two Pst strains that are virulent on these accessions suggested that known microbe-associated molecular patterns (MAMPs) or effectors are not involved in the resistance. We developed an F2 population from a cross between one T1-resistant accession, LA2109, and a susceptible tomato cultivar to investigate the genetic basis of this resistance. Linkage analysis using whole-genome sequence of 58 F2 plants identified quantitative trait loci (QTL), qRph1, in a 5.8-Mb region on chromosome 2, and qRph2, in a 52.4-Mb region on chromosome 8, which account for 24 and 26% of the phenotypic variability, respectively. High-resolution mapping of qRph1 confirmed it contributed to T1 resistance and delimited it to a 1060-kb region containing 139 genes, including three encoding receptor-like proteins (RLPs) and 17 encoding receptor-like protein kinases (RLKs). One RLK gene, Solyc02g072470, is a promising candidate for qRph1, as it is highly expressed in LA2109 and induced on treatment with MAMPs. qRph1 might be useful for enhancing resistance to race 1 strains and its future characterization could provide insights into the plant immune system.

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