Identification and validation of a major quantitative trait locus for spike length and compactness in the wheat ( L.) line Chuanyu12D7.

Spike length (SL) and spike compactness (SC) are crucial traits related to wheat ( L.) yield potential. In this study, a backcrossed inbred lines (BILs) population segregating for SL/SC was developed by using a commercial variety chuanyu25 as recurrent parent and a backbone parent Chuanyu12D7. Bulked segregant analysis (BSA) combined with the Wheat 660K SNP array was performed to conduct quantitative trait locus (QTL) mapping. A major and stable SL/SC QTL (designated as ) was identified on chromosome 2DS, explaining 45.63-59.72% of the phenotypic variation. was mapped to a 102.29-Kb interval by flanking SNPs AX-110276364 and AX-111593853 using a BCF population. Since is linked to the gene, their additive effects on plant type and spike type were analysed. Remarkably, the superior allele of combined with can increase SL and TGW, and decrese SC without any apparent trade-offs in other yield-related traits. In addition, the closely linked kompetitive allele-specific PCR (KASP) markers of this locus were developed for marker-assisted selection (MAS) breeding. Four genes within the physical interval were considered as potential candidates based on expression patterns as well as orthologous gene functions. These results laid the foundation for map-based cloning of the gene(s) underlying its potential application in wheat ideotype breeding.