Novel haplotypes and networks of AVR-Pik alleles in Magnaporthe oryzae
Novel haplotypes and networks of AVR-Pik alleles in Magnaporthe oryzae
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DOI：
10.1186/s12870-019-1817-8
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发表时间：
2019-05-16
影响因子：
5.3
通讯作者：
Wang, Raoquan
中科院分区：
文献类型：
--
作者：
Li, Jinbin;Wang, Qun;Wang, Raoquan
稻瘟病是世界范围内危害水稻最严重的真菌病害之一。稻瘟病菌的无毒基因（AVR）被水稻的同源抗病基因（R）识别，并触发小种特异性抗性。AVR的变化是新比赛的主要驱动力之一。检测从水稻产区采集的稻瘟病菌群体分离物中AVR基因的变异将有助于评估R基因在水稻产区的有效性。Pik基因含有5个R等位基因（Pik、Pikh、Pikp、Pikm和Piks），对应于M的AVR等位基因（AVR-Pik/kh/kp/km/ks）。米。Pik基因特异性识别并防止M.包含AVR-Pik的磁盘。M.结果通过分析AVR-Pik等位基因的DNA序列变异，并在田间条件下测定其对同源抗病基因Pik等位基因的无毒性，研究了AVR-Pik等位基因的可能进化途径。对366株M.来自中国云南省的猪携带AVR-Pik等位基因。在云南6个地区的分离物中，66.7%~ 90.3%的分离物携带AVR-Pik等位基因。此外，10个AVR-Pik单倍型编码5个新的AVR-Pik变异体中确定的201株。AVR-Pik等位基因通过逐步碱基替换从无毒力形式进化为毒力。这些研究结果表明，AVR-Pik等位基因正选择和突变是负责击败种族特异性抗性Pik等位基因在nature.ConclusionsWe证明了AVR-Pik等位基因的多态性和分布在云南省，中国。通过对AVR-Pik不同单倍型的致病性分析，首次揭示了AVR-Pik等位基因在云南稻区的回避和逐步进化。功能性AVR-Pik具有多样的序列结构，并且在自然界中处于正选择下。
BackgroundRice blast disease is one of the most destructive fungal disease of rice worldwide. The avirulence (AVR) genes of Magnaporthe oryzae are recognized by the cognate resistance (R) genes of rice and trigger race-specific resistance. The variation in AVR is one of the major drivers of new races. Detecting the variation in the AVR gene in isolates from a population of Magnaporthe oryzae collected from rice production fields will aid in evaluating the effectiveness of R genes in rice production areas. The Pik gene contains 5 R alleles (Pik, Pikh, Pikp, Pikm and Piks) corresponding to the AVR alleles (AVR-Pik/kh/kp/km/ks) of M. oryzae. The Pik gene specifically recognizes and prevents infections by isolates of M. oryzae that contain AVR-Pik. The molecular variation in AVR-Pik alleles of M. oryzae and Pik alleles of rice remains unclear.ResultsWe studied the possible evolutionary pathways of AVR-Pik alleles by analyzing their DNA sequence variation and assaying their avirulence to the cognate Pik alleles of resistance genes under field conditions in China. The results of PCR products from genomic DNA showed that 278 of the 366 isolates of M. oryzae collected from Yunnan Province, China, carried AVR-Pik alleles. Among the isolates from six regions of Yunnan, 66.7-90.3% carried AVR-Pik alleles. Moreover, 10 AVR-Pik haplotypes encoding five novel AVR-Pik variants were identified among 201 isolates. The AVR-Pik alleles evolved to virulent from avirulent forms via stepwise base substitution. These findings demonstrate that AVR-Pik alleles are under positive selection and that mutations are responsible for defeating race-specific resistant Pik alleles in nature.ConclusionsWe demonstrated the polymorphism and distribution of AVR-Pik alleles in Yunnan Province, China. By pathogenicity assays used to detect the function of the different haplotypes of AVR-Pik, for the first time, we showed the avoidance and stepwise evolution of AVR-Pik alleles in rice production areas of Yunnan. The functional AVR-Pik possesses diversified sequence structures and is under positive selection in nature.