Genetic Diversity and Evolutionary Analyses Reveal the Powdery Mildew Resistance GenePm21Undergoing Diversifying Selection

文献类型： 外文期刊

第一作者： He, Huagang

作者： He, Huagang;Ji, Jian;Tong, Juan;Feng, Yongqiang;Zhu, Shanying;Li, Hongjie;Wang, Xiaolu;Han, Ran;Liu, Cheng;Bie, Tongde;Zhu, Shanying

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关键词： Dasypyrum villosum; Pm21allele; genetic diversity; evolutionary analysis; diversifying selection; wheat powdery mildew resistance

期刊名称：FRONTIERS IN GENETICS （ 影响因子：4.599； 五年影响因子：4.888 ）

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年卷期： 2020 年 11 卷

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收录情况： SCI

摘要： Wheat powdery mildew caused byBlumeria graminisf. sp.tritici(Bgt) is a devastating disease that threatens wheat production and yield worldwide. The powdery mildew resistance genePm21, originating from wheat wild relativeDasypyrum villosum, encodes a coiled-coil, nucleotide-binding site, leucine-rich repeat (CC-NBS-LRR) protein and confers broad-spectrum resistance to wheat powdery mildew. In the present study, we isolated 73Pm21alleles from different powdery mildew-resistantD. villosumaccessions, among which, 38 alleles were non-redundant. Sequence analysis identified seven minor insertion-deletion (InDel) polymorphisms and 400 single nucleotide polymorphisms (SNPs) among the 38 non-redundantPm21alleles. The nucleotide diversity of the LRR domain was significantly higher than those of the CC and NB-ARC domains. Further evolutionary analysis indicated that the solvent-exposed LRR residues ofPm21alleles had undergone diversifying selection (dN/dS = 3.19734). In addition, eight LRR motifs and four amino acid sites in the LRR domain were also experienced positive selection, indicating that these motifs and sites play critical roles in resistance specificity. The phylogenetic tree showed that 38Pm21alleles were divided into seven classes. Classes A (including originalPm21), B and C were the major classes, including 26 alleles (68.4%). We also identified three non-functionalPm21alleles from four susceptible homozygousD. villosumlines (DvSus-1 to DvSus-4) and two susceptible wheat-D. villosumchromosome addition lines (DA6V#1 and DA6V#3). The genetic variations of non-functionalPm21alleles involved point mutation, deletion and insertion, respectively. The results also showed that the non-functionalPm21alleles in the two chromosome addition lines both came from the susceptible donors ofD. villosum. This study gives a new insight into the evolutionary characteristics ofPm21alleles and discusses how to sustainably utilizePm21in wheat production. This study also reveals the sequence variants and origins of non-functionalPm21alleles inD. villosumpopulations.

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