Pm67, a new powdery mildew resistance gene transferred from Dasypyrum villosum chromosome 1V to common wheat (Triticum aestivum L.)

Abstract

Powdery mildew, caused by the biotrophic fungus Blumeria graminis f. sp. tritici (Bgt), is a global disease that poses a serious threat to wheat production. To explore additional resistance gene, a wheat-Dasypyrum villosum 1V#5 (1D) disomic substitution line NAU1813 (2n = 42) with high level of seedling resistance to powdery mildew was used to generate the recombination between chromosomes 1V#5 and 1D. Four introgression lines, including t1VS#5 ditelosomic addition line NAU1815, t1VL#5 ditelosomic addition line NAU1816, homozygous T1DL·1VS#5 translocation line NAU1817, and homozygous T1DS·1VL#5 translocation line NAU1818 were developed from the selfing progenies of 1V#5 and 1D double monosomic line that derived from F1 hybrids of NAU1813/NAU0686. All of them were characterized by fluorescence in situ hybridization, genomic in situ hybridization, 1V-specific markers analysis, and powdery mildew tests at different developmental stages. A new powdery mildew resistance gene named Pm67 was physically located in the terminal bin (FL 0.70–1.00) of 1VS#5. Lines with Pm67 exhibited seedling stage immunity and tissue-differentiated reactions at adult plant stage. The sheaths, stems, and spikes of the Pm67 line were still immune, but the leaves showed a low degree of susceptibility. Microscopic observation showed that most penetration attempts were stopped in association with papillae on the sheath, and colonies cannot form conidia on the susceptible leaf of Pm67 line at adult plant stage, suggesting that the defence layers of the Pm67 line is tissue-differentiated. Thus, the T1DL·1VS#5 translocation line NAU1817 provides a new germplasm in wheat breeding for improvement of powdery mildew resistance.