WheatTaNADPOpromotes spot blotch resistance

Abstract

ABSTRACTBipolaris sorokinianais a common soil-borne fungal pathogen that can infect various organs of wheat (Triticum aestivumL.), causing diseases such as spot blotch, common root rot, head blight, and black point. The genetic basis of wheat resistance toB. sorokinianais not yet fully understood. In this study, a natural population of 1,302 global common wheat germplasms was established and inoculated withB. sorokinianaat the seedling stage in a greenhouse. Resistance to spot blotch was assessed, revealing that only about 3.8% of the germplasms exhibited moderate or higher resistance levels. A genome-wide association study (GWAS) using high-density 660K single nucleotide polymorphism (SNP) data identified a region on chromosome 1BL (621.2-674.0 Mb) with 9 SNPs significantly associated (p< 10e-4) with spot blotch resistance, designated asQsb.hebau-1BL. RNA sequencing and qRT-PCR assays showed that the geneTraesCS1B02G410300, encoding nicotinamide-adenine dinucleotide phosphate-binding oxidoreductase (TaNADPO), was significantly induced byB. sorokiniana. Five SNP variations were found in the promoter region ofTaNADPOin wheat lines with or withoutQsb.hebau-1BL. Transient expression ofTaNADPOinNicotiana benthamianaleaves showed a cytoplasmic subcellular localization of the fusion protein with a green fluorescent protein (GFP) tag. Wheat transgenic lines overexpressingTaNADPOexhibited significantly enhanced resistance to spot blotch compared to wildtype plants, with higher accumulation of reactive oxygen species (ROS). The knockout EMS mutant ofTriticum turgidum NADPO(tdnadpo-K2561, Gln125*) showed significantly reduced resistance to spot blotch and lower ROS accumulation compared to wildtype plants. In summary,TaNADPOhas been identified as a crucial gene for resistance toB. sorokiniana, providing valuable insights for developing spot blotch-resistant wheat varieties through molecular breeding techniques.