湖南桃江病圃稻瘟病菌的无毒基因及水稻抗瘟单基因联合抗性分析

Analysis of avirulence genes of Magnaporthe oryzae and resistance association of monogene against blast from rice blast nursery in Hunan Taojiang

摘要:

【目的】鉴定湖南省桃江病圃稻瘟病菌无毒基因型，为合理搭配种植湖南省水稻抗瘟品种和抗病育种提供依据。【方法】在湖南桃江病圃采集水稻品种“丽江新团黑谷”(LTH)稻瘟菌病样，用单孢分离法分离稻瘟病菌单孢并纯化获得单孢菌株，用针刺离体法将菌株接种到以“LTH”为轮回亲本培育而成的24个含单抗瘟基因的水稻5叶期第5叶片上，对供试菌株进行无毒基因鉴定，并应用联合致病性系数和联合抗病性系数分析抗瘟基因组合间的互作。【结果】供试92个稻瘟病单孢菌株含有全部的24个无毒基因，对24个已知含单抗瘟基因的水稻材料表现出不同程度的毒力水平，含水稻抗瘟基因Pi-20对供试菌株抗菌频率最高，达54.35%；通过联合致病性系数和联合抗病性系数分析抗瘟基因组合间的互作，结果表明最佳搭配组合为Pi-20×Pi-ks (RAC=0.28，PAC=0.23)。【结论】湖南省桃江病圃稻瘟病菌致病力较强，24个抗瘟基因多已感病化，含抗性基因Pi-20与Pi-k、Pi-ks、Pi-3组合的水稻品种目前可在湖南省推广利用，但需研究引进新的抗瘟基因。

Abstract:

[Objective] We identified avirulence genes of rice blast fungus in Taojiang, Hunan Province, to deploy rice blast resistant varieties and blast resistant breeding in Hunan. [Methods] We collected samples of leaf blast of Lijiangxintuanheigu (LTH) in Taojiang and isolated blast fungi through single spore isolation. Avirulence genes of these fungi were identified by in vitro after being inoculated onto the 5th leaf of the 24 monogenic near-isogenic lines against blast at 5 leaves stage which is cultivated from LTH with known blast-resistance gene. We analyzed the interactions between the blast-resistance genes combining pathogenicity association coefficient (PCA) with resistance association coefficient (RAC). [Results] The total 92 strains of M. oryzae contain the whole 24 avirulent genes based on 24 near-isogenic lines, and they also showed different levels of virulence, where the anti-stain frequency of Pi-20 was the highest up to 54.35%. Moreover, the optimal combination of resistant genes was Pi-20×Pi-ks (RAC=0.28, PAC=0.23). [Conclusion] The virulence of M. oryzae was strong and 24 blast-resistant monogenes were nearly diseased in Taojiang rice blast nursery of Hunan Province. At present, rice cultivars carrying resistant genes combinations (Pi-20 with Pi-k, Pi-ks, Pi-3) can be popularized in Hunan Province, but new blast resistance genes must be further imported.