Characterization of a stable QTL for flag leaf width and its genetic effects on yield-related traits

Background Flag leaf width (FLW) is an important controller of flag leaf size in wheat ( Triticum aestivum L.) and is closely related to yield-related traits. Results In this study, wheat Kenong 9204 (KN9204) × Jing 411 recombinant inbred mapping populations (KJ-RILs) were used as materials in a quantitative trait locus (QTL) analysis, and a major and stable QTL for FLW, qFlw-4B , was detected in multiple environments on chromosome 4B. KJ-RILs and a natural mapping population consisting of 314 breeding varieties/advanced lines were also utilized to further investigate the genetic and selection effects of qFlw-4B in wheat breeding. Compared with the Jing 411 haplotype ( Hap-J411 ), the KN9204 haplotype of the qFlw-4B region, Hap-KN9204 , significantly increased FLW as well as improved yield-related traits, such as spikelet number per spike, kernel number per spike, and spike number per plant in both KJ-RILs and the natural populations. The selection effect revealed that the superior haplotype of qFlw-4B had a relatively high selection intensity in both domestically and internationally bred varieties, and its selection utilization rate gradually increased. In addition, the InDel marker 4BFLW-290 targeting qFlw-4B was developed. This study was an important reference for the utilization of qFlw-4B in wheat molecular breeding. Conclusion A major stable QTL for FLW was identified in wheat, and its genetic effects on yield related-traits, as well as its potential use value in molecular breeding programs, were characterized. In addition, an InDel marker closely linked to the stable major QTL was developed. This study enhanced the understanding of the potential genetic mechanisms underlying wheat FLW and provided crucial information for the future genetic improvement and molecular breeding of wheat varieties.