Verification of the Fusarium-Increasing Properties of the Dominant Dwarfing Gene Ddw1 in triticale (×Triticosecale)

Abstract

Dwarfing genes that are considerably reducing plant height are used in many cereals. In triticale, the rye-derived dominant dwarfing gene Ddw1 was introgressed in commercial varieties. It has already been shown that this gene increases Fusarium head blight (FHB) susceptibility in one segregating population. We aimed for verifying this effect in the genetically unrelated doubled haploid (DH) population Cando (Ddw1) × Tritikon (ddw1), with 182 progenies in an experiment with artificial inoculation across six location–year combinations (environments). Linkage mapping was performed with DArTseq markers. The progenies significantly (p < 0.001) varied for FHB severity, plant height and heading stage with high entry-mean heritabilities (0.85–0.98). The population showed a bimodal distribution for plant height. A significant QTL on chromosome 5RL was found for all three traits explaining 38%, 62% and 43% of the genotypic variation for FHB severity, plant height and heading stage, respectively, and most likely representing Ddw1. This gene increased FHB severity by 5.6 percentage points, delayed heading by 2.7 EC stages and reduced plant height by 29.6 cm on average. To use this gene in practical triticale breeding, the genetic background must be enriched with FHB resistance QTL to counterbalance the negative effect of Ddw1 either by introgression of major FHB QTL from exotic sources or by genomic selection within the adapted gene pool.