LAUSR

High temperature stress (HS) will increasingly affect crop yield worldwide. In order to determine the genetic basis of thermotolerance of seed-set in maize in field conditions, a QTL mapping in a recombinant inbred line (RIL) population was performed using a collection of 8329 high-density single nucleotide polymorphisms (SNP) markers developed in this study, combined with a genome-wide association study (GWAS) of 261 diverse maize lines using 259,973 SNPs. In total, 4 quantitative trait loci (QTLs) and 17 genes associated with 42 SNPs related to thermotolerance of seed-set were identified by linkage mapping and GWAS, respectively. Four candidate genes among them were found in both linkage mapping and GWAS. Thermotolerance on seed-set were increased significantly in the near-isogenic lines (NILs) incorporating the four candidate genes in a susceptible parent background. Moreover, the expression profiles of two of the four candidate genes showed that they were induced by high temperature in maize tassel in the tolerant parent background. These genetic analyses indicated that thermotolerance of maize seed-set is regulated by multiple genes with minor effect, in which calcium signaling plays a core role. The pyramiding breeding with beneficial alleles and candidate genes could improve seed-set and yield of maize under HS.