The current study aimed to analyze the allelic variations in major heading-date regulating genes and conducted a genome-wide association study (GWAS) using a wheat core collection to explore the genetic loci related to heading date under fall sowing conditions in East Asia.

Significant differences in heading dates were observed based on the genotype of the Ppd-D1 gene, whereas no significant difference was seen based on the genotypes of Vrn-1 and Ppd-A1. Furthermore, despite Korean varieties exhibiting extremely early heading worldwide, the allelic diversity in Vrn-1 and Ppd-1 is limited. Through GWAS, using the entire wheat core collection (n = 518), two significant SNPs (AX-95222044 and AX-94685526) were selected as the major loci associated with the heading date.

Two more SNPs (AX-94550996 and AX-94970315) were chosen from the GWAS using the accessions (n = 231) carrying the Vrn-1 and Ppd-1 genotypes that were identical to 40 Korean wheat varieties. Among them, genes harboring AX-95222044 and AX-94970315 had previously been reported to be associated with wheat heading dates, and the gene carrying AX-94550996 was reported to be related to flowering time in the orthologous gene of Arabidopsis.

Therefore, resources possessing early heading alleles for the four SNPs identified through GWAS, along with Ppd-D1, were considered potential candidates for early heading breeding materials. Five Korean resources (IT nos. 14303, 15864, 116118, 175533, and 237807) met this criterion, with an average DTH of 179 days. Utilization of the four SNPs selected from GWAS in this study could help develop molecular markers for breeding early maturing varieties in East Asia.