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STAYGREEN, STAY HEALTHY: a loss‐of‐susceptibility mutation in the STAYGREEN gene provides durable, broad‐spectrum disease resistances for over 50 years of US cucumber production
Author(s) -
Wang Yuhui,
Tan Junyi,
Wu Zhiming,
VandenLangenberg Kyle,
Wehner Todd C.,
Wen Changlong,
Zheng Xiangyang,
Owens Ken,
Thornton Alyson,
Bang Hailey H.,
Hoeft Eric,
Kraan Peter A. G.,
Suelmann Jos,
Pan Junsong,
Weng Yiqun
Publication year - 2019
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.15353
Subject(s) - biology , cucumis , genetics , nonsynonymous substitution , candidate gene , plant disease resistance , locus (genetics) , gene , quantitative trait locus , downy mildew , single nucleotide polymorphism , allele , botany , genotype , genome
Summary The Gy14 cucumber ( Cucumis sativus ) is resistant to oomyceteous downy mildew ( DM ), bacterial angular leaf spot ( ALS ) and fungal anthracnose ( AR ) pathogens, but the underlying molecular mechanisms are unknown. Quantitative trait locus ( QTL ) mapping for the disease resistances in Gy14 and further map‐based cloning identified a candidate gene for the resistant loci, which was validated and functionally characterized by spatial‐temporal gene expression profiling, allelic diversity and phylogenetic analysis, as well as local association studies. We showed that the triple‐disease resistances in Gy14 were controlled by the cucumber STAYGREEN ( Cs SGR ) gene. A single nucleotide polymorphism ( SNP ) in the coding region resulted in a nonsynonymous amino acid substitution in the Cs SGR protein, and thus disease resistance. Genes in the chlorophyll degradation pathway showed differential expression between resistant and susceptible lines in response to pathogen inoculation. The causal SNP was significantly associated with disease resistances in natural and breeding populations. The resistance allele has undergone selection in cucumber breeding. The durable, broad‐spectrum disease resistance is caused by a loss‐of‐susceptibility mutation of Cs SGR . Probably, this is achieved through the inhibition of reactive oxygen species over‐accumulation and phytotoxic catabolite over‐buildup in the chlorophyll degradation pathway. The Cs SGR ‐mediated host resistance represents a novel function of this highly conserved gene in plants.