Characterization of Pm68, a new powdery mildew resistance gene on chromosome 2BS of Greek durum wheat TRI 1796

Authors: HE, HUAGANG - Jiangsu University; LIU, RENKANG - Jiangsu University; MA, PENGTAO - Yantai University; DU, HAONAN - Jiangsu University; ZHANG, HUANHUAN - Jiangsu University; WU, QIUHONG - Chinese Academy Of Sciences; YANG, LIJUN - Hubei Academy Of Agricultural Sciences; GONG, SHUANGJUN - Hubei Academy Of Agricultural Sciences; LIU, TIANLEI - Jiangsu University; HUO, NAXIN - University Of California, Davis; Gu, Yong; ZHU, SHANYING - Jiangsu University

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2020
Publication Date: 9/11/2020
Citation: He, H., Liu, R., Ma, P., Du, H., Zhang, H., Wu, Q., Yang, L., Gong, S., Liu, T., Huo, N., Gu, Y.Q., Zhu, S. 2020. Characterization of Pm68, a new powdery mildew resistance gene on chromosome 2BS of Greek durum wheat TRI 1796. Journal of Theoretical and Applied Genetics. 134:53-62. https://doi.org/10.1007/s00122-020-03681-2.
DOI: https://doi.org/10.1007/s00122-020-03681-2

Interpretive Summary: Wheat is one of the most widely cultivated cereal crops in the world, providing about 20 % of daily dietary calories consumed by humans. Wheat production is greatly threatened by powdery mildew disease, caused by the fungal pathogen Blumeria graminis f. sp. tritici (Bgt) that has complex and variable virulence structures in natural populations. Exploiting and utilizing broad-spectrum powdery mildew resistance (Pm) genes are important and urgent to effectively control the mildew disease. Although the tetraploid durum wheat is a relatively small cereal crop mainly used for pasta making, it possesses good resistance to leaf rust, stem rust, and stripe rust and has been widely used for wheat improvement. In this study, we mapped a powdery mildew resistance gene in durum wheat using a mapping population derived a cross between a resistance line, TRI1796, and susceptible line, PI584832. This highly effective resistance gene, Pm68, was mapped to the short arm of chromosome 2B and flanked by two molecular markers with a short genetic distance of 0.22 centimorgan (cM). This new broad-spectrum powdery mildew resistance gene and the closely linked molecular markers developed are valuable resources for improvement of both common wheat and durum wheat through marker-assisted breeding programs.

Technical Abstract: Durum wheat (Triticum turgidum L. var. durum Desf.) is not only an important cereal crop for pasta making, but also a genetic resource for common wheat improvement. In the present study, a Greek durum wheat TRI 1796 was found to confer high resistance to all tested isolates of Blumeria graminis f. sp. tritici (Bgt). Inheritance study on the F1 plants and the F2 population derived from the cross TRI 1796/PI 584832 revealed that the resistance in TRI 1796 was controlled by a single dominant gene, herein designated Pm68. Using bulked segregant RNA-Seq (BSR-Seq) analysis combined with molecular analysis, Pm68 was mapped to the terminal part of the short arm of chromosome 2B (2BS) which was flanked by markers Xdw04 and Xdw12/Xdw13 with genetic distances of 0.22 cM each. According to the reference genome of durum wheat cv. Svevo, the corresponding physical region spanned the Pm68 locus was about 1.78-Mb, in which, a number of disease resistance-related genes were annotated. This study reports the new broad-spectrum powdery mildew resistance gene Pm68 that would be a valuable resource for improvement of both common wheat and durum wheat. The co-segregated markers (Xdw05 – Xdw11) developed here would be useful tools for marker-assisted selection (MAS) in breeding.