Mutagenesis-Derived Resistance to Black Point in Wheat

Abstract

Black point, a severe global wheat disease, necessitates deploying resistant cultivars for effective control. Despite this, susceptibility remains prevalent among most wheat cultivars. Identifying new sources of resistance and understanding their mechanisms are crucial for breeding resistant cultivars. This study pinpointed black point resistance in an EMS-mutagenized wheat population of Wanyuanbai 1 (WYB) and analyzed resistant mutants using RNA-Seq. The findings reveal: (i) wyb-18, among 10008 EMS-mutagenized lines, exhibited robust resistance with significantly lower black point incidence under artificial Bipolaris sorokiniana inoculation in 2020 and 2021 (average incidence of 5.2% over two years), markedly reduced compared to WYB (50.9%). (ii) wyb-18 kernels displayed black point symptoms at 12 days after inoculation (dai), three days later than WYB. At 15 dai, wyb-18 kernels had isolated black spots, unlike WYB kernels, where the entire embryo turned black. (iii) wyb-18 showed heightened antioxidant enzyme activity, including peroxidase, catalase, and superoxide dismutase. (iv) Analysis of 543 differentially expressed genes (DEGs) between wyb-18 and WYB at 9 dai identified enrichment in the MAPK signaling pathway through KEGG analysis. Ten genes in this pathway exhibited upregulated expression, while one was downregulated in wyb-18. Among these, PR1, WRKY11, SAPK5, and TraesCS1A02G326800 (Chitin recognition protein) consistently showed upregulation in wyb-18, making them potential candidates for black point resistance. These results offer valuable germplasm for breeding and novel insights into the mechanisms of black point resistance.