Xie Pengfei, Liu Jia, Lu Ruisen, Zhang Yanmei, Sun Xiaoqin
Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China.
Front Genet. 2022 Sep 6;13:991900. doi: 10.3389/fgene.2022.991900. eCollection 2022.
The exploitation of plant disease resistance () genes in breeding programs is an effective strategy for coping with pathogens. An understanding of gene variation is the basis for this strategy. Rice blast disease, caused by the fungus, is a destructive disease of rice. The rice blast resistance gene represents a new class of plant gene because of its novel extracellular domain. We investigated the nucleotide polymorphism, phylogenetic topology and evolution patterns of the gene among 67 cultivated and wild rice relatives. The gene originated early in the basal Poales and has remained as a single gene without expansion. The striking finding is that susceptible alleles might be derived from a single nucleotide substitution of the resistant alleles after the split of subspecies. Functional pleiotropy and linkage effects are proposed for the evolution and retention of the disease-susceptible alleles in rice populations. One set of DNA primers was developed from the polymorphic position to detect the functional nucleotide polymorphism for disease resistance of the gene based on conventional Polymerase Chain Reaction. The nucleotide diversity level varied between different domains of the gene, which might be related to distinct functions of each domain in the disease defense response. Directional (or purifying) selection appears dominant in the molecular evolution of the gene and has shaped its conserved variation pattern.
在育种计划中利用植物抗病（）基因是应对病原体的有效策略。了解基因变异是该策略的基础。由真菌引起的稻瘟病是水稻的一种毁灭性病害。稻瘟病抗性基因因其新颖的细胞外结构域而代表了一类新的植物基因。我们研究了67个栽培稻和野生稻近缘种中该基因的核苷酸多态性、系统发育拓扑结构和进化模式。该基因起源于基部禾本目早期，并且一直作为单个基因未发生扩增。引人注目的发现是，易感等位基因可能在亚种分化后由抗性等位基因的单个核苷酸替换产生。针对水稻群体中感病等位基因的进化和保留提出了功能多效性和连锁效应。基于传统聚合酶链反应，从多态性位点开发了一组DNA引物，以检测该基因抗病性的功能性核苷酸多态性。该基因不同结构域之间的核苷酸多样性水平有所不同，这可能与每个结构域在病害防御反应中的不同功能有关。定向（或纯化）选择在该基因的分子进化中似乎占主导地位，并塑造了其保守的变异模式。
