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.