Quantitative trait locus mapping for panicle exsertion length in common wheat using two related recombinant inbred line populations

The improvement of panicle exsertion length (PEL) in wheat (Triticum aestivum L.) breeding programs is an emerging objective to improve yield potential, and serves as a complement to the wheat ideotype. In this study we aimed to advance the current understanding of genetic mechanisms underlying panicle exsertion in wheat. Two related recombinant inbred line populations sharing common parent H461 were used to identify and compare quantitative trait loci (QTL) controlling PEL. Using two high-density genetic linkage maps, 13 putative QTL for PEL were detected on chromosomes 1B, 1D, 2B, 2D, 4A, 4B, 5B, 6D, 7A, and 7B; each QTL explained 5.7-15.6% of the phenotypic variation. Among these 13 QTL, nine were independent; the other two pairs derived from H461 were validated to be common QTL based on newly developed high-resolution melt markers. Further, plant height (PH) was measured to perform covariance QTL analysis with eight major QTL; three of them derived from the wheat variety CM107 were not affected by PH. Pleiotropic effects on yield-related traits (PH, spike length, spikelet number per spike, spikelet density, kernel number per spike, kernel length, and thousand kernel weight) of the eight major QTL were also evaluated. These eight QTL may be valuable for fine mapping and marker-assisted selection in wheat breeding programs.