Identification of Spike Length Gene and Development of KASP Markers in Wheat.

Spike length is a critical trait influencing the yield potential of wheat (Triticum aestivum L.). However, there has been limited research on spike-length-related genes in wheat. Moreover, the scarcity of stable markers for spike-related traits has restricted marker-assisted selection-based breeding. In this study, a novel long-spike mutant material (LS1) was generated from wheat variety 'Aikang 58' (AK58) using ethyl methanesulfonate. We established an F2 segregating population by crossing AK58 with LS1. Morphological analyses of this population indicated that spike length is a dominant quantitative trait regulated by multiple genes. Bulked segregant analysis (BSA) technology was used to preliminarily identify nine candidate regions associated with spike length traits. These regions were mainly in a 7.22 Mb interval (673.84-713.26 Mb) on chromosome 5A and in a 2.34 Mb interval (714.83-717.69 Mb) on chromosome 7B. Twelve candidate genes were identified within these regions. Furthermore, two kompetitive allele specific polymerase chain reaction (KASP) markers (KASP-LS1-681460621 and KASP-LS1-692013966) associated with spike length traits were developed. Both KASP markers effectively genotyped parental lines and the F2 population. Our study results provide a theoretical foundation for the genetic improvement of spike-length-related traits in wheat.