QTL Validation for Agronomic Traits On 3A Chromosome of Hexaploid Wheat Using Recombinant Inbred Chromosome Lines.

Quantitative trait loci (QTLs) that control agronomic traits such as grain yield and its components are the most important economic traits for wheat (Triticum aestivum) improvement.  Based on previous study using a reciprocal chromosome substitution lines between wheat cultivars of Wichita (WI) and Cheyenne (CNN), a recombinant inbreed chromosome lines (RICLs) developed for the 3A chromosome in the CNN background CNN(RICLs-3A) indicated the presence of major grain yield QTL that explained 28% of the phenotypic variance.   In the current study WI(RICLs-3A) population where the RICLs involve WI and CNN chromosome 3A in WI background were used to validate the QTLs detected in the CNN(RICL3A) population.  The objectives of this study were to (1) identify and map QTLs for grain yield and its component traits and; (2) compare the detected QTLs in WI(RICL3A) to those obtained in the CNN(RICL3A).  A population of 90 WI(RICLs3A) developed through doubled haploid (DH) system were planted at three locations in Nebraska (Lincoln, Mead, and North Platte) during 2007/2008 cropping season.  QTLs were detected for anthesis date, plant height, grain yield, grain volume weight, and 1000-kernel weight.  A grain yield QTL detected at Lincoln and in the combined analysis explained 17% of the phenotypic variance and the substitution of CNN allele for a WI allele decreased grain yield by 118 kg ha^-1.  This grain yield QTL was the major grain yield QTL detected in CNN(RICL3A) population and it was at similar position.  In addition to grain yield, grain volume weight and 1000-kernel weight QTLs were detected in the combined analysis that explained 38% and 14% of the phenotypic variance, respectively. Most of the major chromosome 3A QTLs reported in the previous CNN(RICL3A) studies were detected in the current study even though it was conducted in a different genetic background.  The WI 3A alleles in the previous CNN(RICL3A) study increased grain yield and yield components traits and, as expected, the CNN 3A alleles in the current WI(RICL3A) study decreased grain yield and yield components traits.