Molecular Mapping of QTL for Fusarium Head Blight Resistance in a Doubled Haploid Population of Chinese Bread Wheat.

Fusarium head blight (FHB) is a destructive disease of wheat worldwide, particularly in China. To map genetic loci underlying FHB resistance, a doubled haploid (DH) population consisting of 174 lines was developed from a cross between widely grown Chinese cultivars Yangmai 16 and Zhongmai 895. The DH population and parents were evaluated in field nurseries at Wuhan in 2016-2017 and 2017-2018 with both spray inoculation and natural infection, and at Jingzhou in 2017-2018 with grain-spawn inoculation. The DH lines were genotyped with a wheat 660K SNP array. FHB index, plant height, anther extrusion, and days to anthesis were recorded and used for QTL analysis. Seven QTL for FHB resistance were mapped to chromosome arms 3BL, 4AS, 4BS, 4DS, 5AL, 6AL, and 6BS, in at least two environments. QFhb.caas-4BS and QFhb.caas-4DS co-located with semi-dwarfing alleles Rht-B1b and Rht-D1b, respectively, and were also associated with anther extrusion. The other five QTL were genetically independent of the agronomic traits, indicating their potential value in breeding for FHB resistance. Based on correlations between FHB indices and agronomic traits in this population, we concluded that increasing plant height to some extent would enhance FHB resistance, anther extrusion played a more important role in environments with less severe FHB, and days to anthesis was independent of FHB response when viewed across years. PCR-based markers were developed for the 3BL and 5AL QTL, which were detected in more than three environments. The InDel marker InDel_AX-89588684 for QFhb.caas-5AL was also validated on a wheat panel, confirming its effectiveness for marker-assisted breeding for improvement of FHB resistance.