谷瘟病菌无毒基因AVR1-CO39序列变异及遗传多样性分析

 谷瘟病是谷子上毁灭性病害之一,为了探讨不同地区谷瘟病菌群体的遗传多样性,对我国11个省(自治区)171株谷瘟病菌的无毒基因AVR1-CO39进行扩增测序,并利用ClustalX2.0和DnaSP5.0软件对测序结果进行分析。结果表明,171株谷瘟病菌单孢菌株AVR1-CO39的CDS编码区共有40个多态性位点,依据序列之间的核苷酸差异划分为37个单倍型,H1型为绝对优势单倍型。我国11个省份谷瘟病菌群体的AVR1-CO39具有较高的遗传多态性,由于存在较为频繁的基因交流,种群之间没有明显的遗传分化。种群内部的遗传分化是谷瘟病菌遗传分化的主要方式,错配分布检测结果显示进化过程中可能出现群体扩张,并且谷瘟病菌的聚类与地理来源没有显著的关系。研究结果表明,谷瘟病菌无毒基因AVR1-CO39具有较高的变异性,以H1为核心单倍型在不断地变异衍生出新的等位基因类型,并且这种变异衍生趋势并不受地理隔离的影响。研究结果可为谷子抗病品种选育,揭示谷瘟病菌无毒基因与谷子抗病基因之间的互作机制提供理论支持。

Analysis of sequence variation and genetic polymorphism in AVR1-CO39 of Magnaporthe oryzae in foxtail millet

Magnaporthe oryzae is one of the most destructive pathogens in foxtail millet. In order to reveal the genetic diversity in multiple population of M. oryzae from different regions of China, AVR1-CO39 of 171 isolates from 11 provinces in China were amplified and sequenced. All nucleotide sequences were analyzed using Clus-talX2.0 and DnaSP5.0 softwares. The results showed 40 segregating sites in the CDS region of AVR1-CO39 genes from all 171 isolates. These were divided into 37 haplotypes based on nucleotide variations, and H1 type was the dominant haplotype. There was high genetic polymorphism in AVR1-CO39 of M. oryzae from 11 provinces of China. Due to frequent gene exchanges, there was no obvious genetic differentiation among populations. The analysis suggested that evolution of AVR1-CO39 gene might be caused by the genetic differentiation within populations. The mismatch detection results showed that group expansion might occur during the evolution process, and the haplotypes clustering group of M. oryzae didn’t show any obvious correlation with geographical origin. The above results showed that the avirulence gene AVR1-CO39 of M. oryzae was highly variable. New allele types derived by constant variation of H1 as the core haplotype, and the variation trend was not affected by geographical isolation. The results of this study could be used for breeding of blast resistance varieties of foxtail millet, and reveal the interaction mechanism between the avirulence genes of M. oryzae and disease resistance genes of foxtail millet.