Pyramiding Three QTL Improved Fusarium Head Blight Resistance in Wheat (Triticum Aestivum L.)

Abstract Fusarium head blight (FHB) is a destructive fungal disease and a major threat to wheat production and food safety worldwide. Mapping of FHB-resistant quantitative trait loci (QTL) has facilitated marker-assisted breeding (MAS). To make better use of the genes/loci from different resistant sources, it is desirable to understand their combined effects on FHB resistance and agronomic traits in different genetic backgrounds. In this study, several FHB resistant donors were first characterized, including Yangmai 18 (YM18) with Fhb1, Zhenmai 9 (ZM9) and Yangmai 16 (YM16) both with QFhb.yaas-2DL and QFhb.yaas-3BL, Ningmai 13 (NM13) with Fhb1 and QFhb.yaas-3BL. TaHRC-KASP, KASP-QFhb-2DL and KASP-QFhb-3BL were used for Fhb1, QFhb.yaas-2DL and QFhb.yaas-3BL, respectively, and they were screened in 77 cultivars/lines. Using the three KASP markers, we developed three RIL populations using MAS from crosses YM18/ZM9, YM18/YM16 and YM18/NM13. F5 populations were investigated for their FHB severity, along with major agronomic traits. Of these three QTL, Fhb1 was the most effective in reducing FHB damage, followed by QFhb.yaas-2DL and QFhb.yaas-3BL. The lines with all three QTL showed significantly more strong resistance than those with only two or one QTL. Fhb1 might have negative effect on kernel number per spike (NKS), but not have significant effect on thousand kernel weight (TKW) and yield. On the other hand, QFhb.yaas-3BL might have positive effect on TKW and yield, and QFhb.yaas-2DL might have positive effect on spike number per plant (NSP) and yield. The addition of these two or three QTL shows positive effects on yield under different genetic backgrounds. Three elite lines, YM18/ZM9-12, YM18/YM16-18 and YM18/YM16-22, with similar FHB resistance to Sumai 3 (SM3) and superior yield to Yangmai 20 (YM20) across multiple environments, have the potential to be released as commercial varieties.