31个水稻主效抗瘟基因对广西稻瘟病菌群体的抗性分析

Resistance analysis of 31 major rice blast resistance genes against Magnaporthe grisea(Hebert)Barr population in Guangxi

【目的】鉴定评价31个已知主效抗瘟基因对广西稻瘟病菌的抗性,明确其在广西水稻育种中的利用价值,为水稻抗瘟新品种的选育、有效聚合抗瘟基因及抗瘟品种合理布局提供理论支撑。【方法】以25个抗瘟单基因系、6个抗稻瘟病近等基因系以及桂R106、红脚占、砦糖3个广西地方抗源品种和感病品种CO39、丽江新团黑谷为供试水稻材料,利用2018—2021年来自广西不同生态稻作区的328个稻瘟病菌单孢菌株对供试31个水稻主效抗瘟单基因进行室内人工喷雾接种抗性评价,并利用稻瘟病区自然诱发病圃对其进行田间抗性鉴定,评价供试水稻材料的抗病性,分析任意2个抗瘟基因的联合抗性频率,进行抗瘟基因与测试菌株的亲和性聚类分析。【结果】31个主效抗瘟基因对测试稻瘟病菌单孢菌株的抗性频率介于0~84.5%,多数基因抗性频率较低,在病区病圃表现高度感病。抗性频率较高的抗瘟基因依次为Pi-k、Pi-km、Pi-9、Pi-1和Pi-z^(5),分别为84.5%、82.9%、80.5%、77.4%和68.9%,这些抗瘟基因在病区病圃也表现出较好的田间抗病性;对任意2个抗瘟基因联合抗性频率分析发现,不同抗瘟基因间组合的联合抗性频率比单个抗瘟基因的抗性频率均有不同程度提高,其中Pi-km×Pi-9的联合抗性频率最高,达97.9%;根据抗瘟基因与测试菌株的亲和性结果进行聚类分析,供试31个主效抗瘟基因可划分为两大组,第I组包括Pi-a(1)等24个抗性较弱的抗瘟基因,抗性频率在0~57.0%,第Ⅱ组包括Pi-9等7个抗性较强的抗瘟基因,抗性频率在41.5%~84.5%。【结论】抗瘟基因Pi-k、Pi-km、Pi-9、Pi-1和Pi-z^(5)对广西稻瘟病菌具有较高的抗性频率,在病圃表现出较好的田间抗性,在广西仍可因地制宜加以利用。基因聚合有望选育出抗谱较广的抗瘟水稻品种。

【Objective】The objective of the study was to identify and evaluate the resistance of 31 known major rice blast resistance genes to Magnaporthe grisea(Hebert)Barr in Guangxi,to make clear their application value in rice breeding in Guangxi,and to provide theoretical support for the selection and breeding of new rice blast resistance varieties,the effective polymerization of resistance genes,and the rational layout of blast resistant varieties.【Method】Twentyfive blast resistant monogenic lines,six near-isogenic lines for resistance to rice blast,and three Guangxi local resistance source varieties of Gui R106,Hongjiaozhan and Zhaitang,and disease-susceptible varieties of CO39,and Lijiang Xintuanheigu,were used as the rice materials for the test.The indoor artificial spray inoculation was used to evaluate the resistance of 31 major rice blast resistance monogenic genes provided for the test using 328 Magnaporthe grisea monosporous strains from different ecological rice-growing region in Guangxi from 2018 to 2021.Field resistance identification was also carried out by natural nursery in blast zone.The resistance of the tested lines was evaluated.The joint resistance frequencies of any two rice blast resistance genes was analyzed.Cluster analysis of compatibility between rice blast resistance genes to the tested strains was conducted.【Result】The resistance frequencies of the 31 major rice blast resistance genes to the monosporous strains of tested pathogens ranged from 0 to 84.5%.Most of the genes showed low resistance frequencies and high susceptibility in the blast zone nursery.The rice blast resistance genes with higher resistance frequencies were Pi-k,Pi-km,Pi-9,Pi-1 and Pi-z^(5),with the values of 84.5%,82.9%,80.5%,77.4%and 68.9%respectively,and these rice blast resistance genes showed better field resistance in the blast zone nursery.The analysis of the joint resistance frequencies of any two rice blast resistance genes revealed that the joint resistance frequencies of different combinations of rice blast resistance genes were higher than those of individual resistance genes to varying degrees,with Pi-km×Pi-9 combination having the highest joint resistance frequency of 97.9%.According to the cluster analysis of compatibility results between rice blast resistance genes and the tested strains,the 31 rice blast resistance genes for testing could be classified into two major groups.Group I included 24 weak rice blast resistance genes such as Pi-a(1)with resistance frequencies ranging from 0 to 57.0%,and group II included 7 strong rice blast resistance genes such as Pi-9 with resistance frequencies ranging from 41.5%to 84.5%.【Conclusion】Rice blast resistance genes Pi-k、Pi-km、Pi-9、Pi-1 and Pi-z^(5) have high resistance frequency to M.grisea in Guangxi and show good field resistance in the blast nursery.Therefore,these genes can still be used for future rice breeding according to local conditions in Guangxi.Gene polymerization is expected to select and breed rice blast resistance varieties with broader resistance spectrum.