title: Phenotypic and genome-wide association analysis of spike ethylene in diverse wheat genotypes under heat stress.
abstract: The gaseous phytohormone ethylene plays an important role in spike development in wheat (Triticum aestivum). However, the genotypic variation and the genomic regions governing spike ethylene (SET) production in wheat under long-term heat stress remain unexplored. We investigated genotypic variation in the production of SET and its relationship with spike dry weight (SDW) in 130 diverse wheat elite lines and landraces under heat-stressed field conditions. We employed an Illumina iSelect 90K single nucleotide polymorphism (SNP) genotyping array to identify the genetic loci for SET and SDW through a genome-wide association study (GWAS) in a subset of the Wheat Association Mapping Initiative (WAMI) panel. The SET and SDW exhibited appreciable genotypic variation among wheat genotypes at the anthesis stage. There was a strong negative correlation between SET and SDW. The GWAS uncovered five and 32 significant SNPs for SET, and 22 and 142 significant SNPs for SDW, in glasshouse and field conditions, respectively. Some of these SNPs closely localized to the SNPs for plant height, suggesting close associations between plant height and spike-related traits. The phenotypic and genetic elucidation of SET and its relationship with SDW supports future efforts toward gene discovery and breeding wheat cultivars with reduced ethylene effects on yield under heat stress.
authors.affiliation: Global Wheat Program, International Maize and Wheat Improvement Center (CIMMYT), El Batan, CP 56237, Mexico.|Plant Biology Department, Lancaster Environment Center, Lancaster University, Lancaster, LA1 4YQ, UK.
authors.forename: Ravi
authors.initials: R
authors.lastname: Valluru
authors.affiliation: Global Wheat Program, International Maize and Wheat Improvement Center (CIMMYT), El Batan, CP 56237, Mexico.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Reynolds
authors.affiliation: Plant Biology Department, Lancaster Environment Center, Lancaster University, Lancaster, LA1 4YQ, UK.
authors.forename: William J
authors.initials: WJ
authors.lastname: Davies
authors.affiliation: Global Wheat Program, International Maize and Wheat Improvement Center (CIMMYT), El Batan, CP 56237, Mexico.
authors.forename: Sivakumar
authors.initials: S
authors.lastname: Sukumaran
mesh_terms: D018533:Biomass; D005030:Ethylenes / Q000378:metabolism*; D055106:Genome-Wide Association Study; D005838:Genotype; D018869:Heat-Shock Response / Q000235:genetics*; D010641:Phenotype; D014908:Triticum / Q000033:anatomy & histology / Q000235:genetics* / Q000502:physiology*
chemical_list: D005030:Ethylenes; C036216:ethylene
keywords: ethylene; genome-wide association (GWA); heat stress; spike dry weight; spike ethylene; wheat