Effect of Allelic Variation in Rht Genes on Grain Yield and Plant Height of Winter Wheat.

Plant height in wheat (Triticum aestivum L.) is controlled in large part by reduced height (Rht) genes, which pleiotropically impact lodging and grain yield. Wheat carries two partially dominant reduced height alleles, Rht-B1b and Rht-D1d, on chromosomes 4B and 4D, respectively. Alone, each of these alleles has a semi dwarfing effect on plant height; however, when combined, they produce a double dwarf plant. The main goals of this study was to analyze the association of Rht-B1 and Rht-D1 with plant height, heading date, and grain yield across environments in a double haploid (DH) population segregating at these loci and to identify additional QTL for these traits. A population of 98 soft red winter wheat (SRWW) lines derived from two SRWW varieties, Neuse (Rht-D1b dwarfing) and Bess (Rht-B1b dwarfing) were used in the study. Phenotypic data such as plant height, heading date, and grain yield was collected at two locations Fayetteville and Newport AR. In addition to phenotypic data collected, lines are currently being screened with KASP markers for Rht-B1, Rht-D1, and Ppd-B1. QTL analysis was performed using a Genetic map containing 6674 markers previously developed by Petersen et al. 2017 and analyzed using a composite interval mapping (CIM) method in WinQTLCart v. 9.3 (NCSU, Wang et al. 2012). As a result, eight QTL for grain yield were identified, explaining 10 to 33% of the phenotypic variation and contributed by both of the parental lines. The most significant QTL for plant height were located on chromosomes 3B and 4D. Both were pleiotropic for plant height measured across growth stages. The QTL for plant height on chromosome 4D was associated with the Rht-D1 locus and explained 16 to 26% of the phenotypic variation for plant height. Latest results will be presented.