QTL mapping for spike length and candidate gene identification in wheat spike development (Triticum aestivum L.)

Spike length (SL) is a crucial factor influencing yield in wheat ( Triticum aestivum L.). In this study, a recombinant inbred line (RIL) population derived from the cross between Guixie 3 and Avocet S was utilized for genetic mapping of quantitative trait loci (QTL) controlling spike length. The results identified a total of 15 QTL distributed on chromosomes 2A, 2D, 4B, 5A, 5D, 6 A, 6B, and 6D. Among these, QSL.gaas-4B was mapped to a physical interval of 25.84–29.20 Mb (3.35 Mb) on chromosome 4B (Reference genome: Chinese Spring v2.1), which was detected across two environments (2023HB, 2024HB) and explained 18.09%–27.53% of the phenotypic variation. Within this mapped interval, there were 56 high-confidence genes with annotated functions. Through comprehensive analysis of functional structure prediction and tissue expression characteristics, TraesCS4B02G035700 and TraesCS4B02G035800 were predicted as candidate genes regulating spike length. The above findings lay a foundation for improving wheat spike length through molecular breeding strategies in the future.