Identification of two major QTL associated with Fusarium crown rot resistance in wheat

Fusarium crown rot (FCR), caused by the fungal genus Fusarium , is a severe soil-borne disease of wheat ( Triticum aestivum ) worldwide. In this study, we identified five quantitative trait loci (QTL) associated with FCR resistance on chromosomes 3A, 3B, 4B (two QTL), and 6A using a population of 128 F 7 recombinant inbred lines (RILs) derived from a cross between the two Chinese cultivars 04zhong 36 and Jinxiu 21. Of these QTL, two major QTL, QFcr.cau-3A and QFcr.cau-4B.1 , were stably detected across multiple trials and explained 14.06% and 18.09%, respectively, of the phenotypic variance based on best linear unbiased prediction (BLUP) data. The resistance alleles at these two loci were derived from the parental lines 04zhong36 ( QFcr.cau-3A ) and Jinxiu 21 ( QFcr.cau-4B.1 ), respectively. We confirmed the effects and stability of QFcr.cau-3A and QFcr.cau-4B.1 in an independent RIL population and in a collection of wheat accessions, respectively. Additionally, we detected a major and stable QTL for plant height, QPh.cau-4B , that overlapped with QFcr.cau-4B. 1. The allele of QPh.cau-4B conferring tallness was from Jinxiu 21. Conditional QTL mapping indicated that although QFcr.cau-4B.1 and QPh.cau-4B showed significant interactions, the effect of QFcr.cau-4B.1 remained significant after the effects of plant height were removed. Field inoculation experiments with the 60 RILs showing the greatest sensitivity or resistance to FCR at the seedling stage detected a significant and positive correlation between seedling and adult plant resistance (correlation coefficient = 0.71). The confidence intervals for QFcr.cau-3A and QFcr.cau-4B.1 contain 264 and 240 high-confidence genes, respectively. Based on gene annotation, sequence variation, and expression patterns, three genes ( TraesCS3A02G373300 , TraesCS3A02G376500 , and TraesCS4B02G222600) were considered as potential candidates for QFcr.cau-3A and QFcr.cau-4B.1 . Our results provide valuable resources for the cloning of FCR resistance loci that can be utilized in FCR resistance breeding programs.