Main Effect and Epistatic QTL Affecting Spike Shattering and Association with Plant Height Revealed in Two Spring Wheat (Triticum aestivum L.) Populations

Abstract Spike shattering can cause severe grain yield loss in wheat. Development of cultivars with reduced shattering but having easy threshability is the target of wheat breeding programs. This study was conducted to determine quantitative trait loci (QTL) associated with shattering resistance, and epistasis among QTL in the Carberry/AC Cadillac and Carberry/Thatcher populations. Response of the populations to spike shattering was evaluated near Swift Current, SK, in four to five environments. Plant height data recorded in different locations and years was used to determine the relationship of the trait with spike shattering. Each population was genotyped and mapped with the wheat 90K Illumina iSelect SNP markers. Main effect QTL were analyzed by MapQTL 6 and epistatic interactions between main effect QTL were determined by QTLNetwork 2.0. Positive correlations were observed both within trait location-year combinations as well as between trait location-year combinations. Carberry contributed two major QTL associated with spike shattering on chromosome arms 4BS and 5AL, detected in both populations. Carberry also contributed two minor QTL on 7AS and 7AL. AC Cadillac contributed five minor QTL on 1AL, 2DL, 3AL, 3DL and 7DS. Nine epistatic QTL interactions were identified, out of which the most consistent and synergistic interaction, that reduced the expression of shattering, occurred between 4BS and 5AL QTL. The 4BS QTL was consistently associated with reduced shattering and reduced plant height in the coupling phase. The present findings shed light on the inheritance of shattering resistance and provide genetic markers for manipulating the trait to develop wheat cultivars.