A remorin gene is implicated in quantitative disease resistance in maize
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Quantitative disease resistance is used by plant breeders to improve host resistance. We demonstrate a role for a maize remorin ( ZmREM6.3 ) in quantitative resistance against northern leaf blight using high-resolution fine mapping, expression analysis, and mutants. This is the first evidence of a role for remorins in plant-fungal interactions.
Quantitative disease resistance (QDR) is important for the development of crop cultivars and is particularly useful when loci also confer multiple disease resistance. Despite its widespread use, the underlying mechanisms of QDR remain largely unknown. In this study, we fine-mapped a known quantitative trait locus (QTL) conditioning disease resistance on chromosome 1 of maize. This locus confers resistance to three foliar diseases: northern leaf blight (NLB), caused by the fungus Setosphaeria turcica; Stewart’s wilt, caused by the bacterium Pantoea stewartii; and common rust, caused by the fungus Puccinia sorghi. The Stewart’s wilt QTL was confined to a 5.26-Mb interval, while the rust QTL was reduced to an overlapping 2.56-Mb region. We show tight linkage between the NLB QTL locus and the loci conferring resistance to Stewart’s wilt and common rust. Pleiotropy cannot be excluded for the Stewart’s wilt and the common rust QTL, as they were fine-mapped to overlapping regions. Four positional candidate genes within the 243-kb NLB interval were examined with expression and mutant analysis: a gene with homology to an F-box gene, a remorin gene (ZmREM6.3), a chaperonin gene, and an uncharacterized gene. The F-box gene and ZmREM6.3 were more highly expressed in the resistant line. Transposon tagging mutants were tested for the chaperonin and ZmREM6.3, and the remorin mutant was found to be more susceptible to NLB. The putative F-box is a strong candidate, but mutants were not available to test this gene. Multiple lines of evidence strongly suggest a role for ZmREM6.3 in quantitative disease resistance.
KeywordsQuantitative Trait Locus Diseased Leaf Area Northern Leaf Blight Quantitative Disease Resistance Nest Association Mapping
We would like to thank Dr. Peter Balint-Kurti for assisting with the field trial in Clayton, NC. We would also like to acknowledge Drs. Randall Wisser, Jesse Poland, Santiago Mideros, and Peter Balint-Kurti for helpful discussions. We also thank Alyssa Cowles, William Miller, Chris Mancuso, Katharine Constas, and Ariel Fialko for their assistance with field work.
Compliance with ethical standards
This work was funded by National Science Foundation award 1127076, the McKnight Foundation, the Cornell University Agricultural Experiment Station federal formula funds, Project No. NYC-153418 received from the National Institute of Food and Agriculture (NIFA), United States Department of Agriculture, and Cornell University. Any opinions, findings, conclusions or recommendations expressed in the publication are those of the author(s) and do not necessarily reflect the view of the National Institute of Food and Agriculture (NIFA), of the United States Department of Agriculture (USDA), or of the other funders.
Conflict of interest
The authors declare that they have no conflict of interest.
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