Effects of D‐Genome Chromosomes and Their A/B‐Genome Homoeologs on Fusarium Head Blight Resistance in Durum Wheat

Abstract

This study aimed to elucidate the effect of D‐genome chromosomes and their homoeologs in A and B genome on Fusarium head blight (FHB) resistance in durum wheat. Evaluation of the ‘Langdon’ (LDN) durum‐'Chinese Spring’ (CS) D‐genome disomic substitution lines for reaction to FHB indicated that chromosome 5A could affect resistance to FHB by generating variation in the 5AQ gene‐controlled spike structure. Also, we found that CS chromosome 6D might contain genes for FHB susceptibility and/or suppression of FHB resistance. Langdon chromosomes 2B and possibly 6A and 6B may contain the genes that enhance FHB resistance. In addition, we added the entire D genome of Aegilops tauschii Coss. RL5286 (2n = 2x = 14, DD) to LDN by producing LDN‐RL5286 amphiploid (2n = 6x = 42, AABBDD) and dissected the A. tauschii D genome in LDN background by producing LDN‐A. tauschii D genome addition lines. The A. tauschii chromosomes 1D and 5D were found to carry the genes that conditioned FHB resistance when they were individually or concurrently added to LDN. The genes for FHB resistance on these two chromosomes seemed to act additively in LDN. The other A. tauschii chromosomes (i.e., 2D, 3D, 4D, 6D, and possibly 7D) might contain the genes that downregulated or suppressed the FHB resistance‐related genes on chromosome 1D or 5D. Apparently, there are complex interactions among the genes on the A. tauschii chromosomes, as well as A‐ and B‐genome chromosomes, for FHB resistance in the durum background. Proper manipulation of the critical chromosomes may lead to the improvement of FHB resistance in durum wheat.