6种水稻初级代谢物对水稻抗瘟性的影响

Effects of six metabolites on rice resistance to blast fungus, Magnaporthe oryzae

  • 摘要: 【目的】解析稻瘟菌与水稻互作时的水稻初级代谢物对稻瘟菌形态发育和水稻防御响应的影响,为生产上水稻稻瘟病绿色防控措施的制定提供基础数据。【方法】利用6种水稻初级代谢物(多巴胺盐酸盐、L-谷氨酰胺、酪胺、α-品烯、L-色氨酸和半乳糖醇)标准品按一定浓度处理稻瘟病菌株,观察代谢物对稻瘟菌菌落生长和菌株形态发育(产孢、菌丝生长和附着胞形成等)的影响;在此基础上,利用相同浓度的代谢物标准品处理稻瘟菌侵染36和48 h时的感病水稻丽江新团黑谷,进行稻瘟病病害调查、防御基因表达分析、活性氧(ROS)含量和过氧化物酶(POD)活性等生理指标测定。【结果】除L-谷氨酰胺和L-色氨酸对生长第9 d的稻瘟病菌菌落生长有显著影响外(P<0.05,下同),其余4种代谢物对稻瘟病菌菌落生长无显著影响(P>0.05,下同);6种水稻初级代谢物对稻瘟菌产孢有抑制作用,其中以酪胺和α-品烯的抑制效果最明显;多巴胺盐酸盐显著抑制稻瘟菌孢子的萌发,其余5种代谢物对稻瘟菌孢子萌发无显著影响;6种水稻初级代谢物对稻瘟菌芽管生长有显著的促进作用;多巴胺盐酸盐和L-色氨酸对附着胞形成有明显的促进作用,L-谷氨酰胺和酪胺对附着胞形成具有抑制作用。6种水稻初级代谢物明显降低稻瘟菌接种36和48 h时的水稻稻瘟病症状和病情指数,其中以多巴胺盐酸盐、酪胺和半乳糖醇对稻瘟病的控制效果最佳;6种水稻初级代谢物对稻瘟菌接种48 h时的稻瘟病控制效果高于其对接菌36 h时的水稻。进一步研究发现多巴胺盐酸盐和半乳糖醇抑制了稻瘟菌侵染36和48 h水稻中茉莉酸(JA)信号基因OsCOI1aOsCOI1bOsMYC2表达,但JA抑制子基因OsJAZ9上调,诱导ROS相关基因OsRbohBOsRbohA以及病程相关基因OsPR10aOsPR5上调,其中以2种代谢物诱导稻瘟菌侵染48 h时水稻中的ROS相关基因和病程相关基因的表达量高于稻瘟菌侵染36 h时的感病水稻;多巴胺盐酸盐诱导稻瘟菌侵染36和48 h时的水稻中POD活性明显增加,ROS含量有一定程度的增加。【结论】水稻初级代谢物通过影响稻瘟菌形态发育、诱导防御相关基因表达和POD活性增加等提高水稻抗瘟性,具有作为植物病害绿色防控激发子的潜力。

     

    Abstract: 【Objective】Analyzing the effect of primary metabolites during interaction of rice and Magnaporthe oryzae on rice blast morphogenesis and defense response,to provide basic data for the formulation of green control measures for rice blast in production.【Method】The six primary metabolites with a certain concentration(dopamine hydrochloride, L-glutamine,tyramine,α-pinene,L-tryptophan,galactinol)were used to treat the rice blast strains to observe the effects of metabolites on colony growth,strain morphology(sporulation,hypha germination and appressorium formation)of M.oryzae. On this basis,the same concentrations of metabolite standards were used to treat 36 h- and 48 h- infected rice to investigate symptom of rice blast disease,analyze defense gene expression,and detect reactive oxygen species(ROS) content and peroxidase(POD)activity.【Result】Except for L-glutamine and L-tryptophan,which had a significant effect on the growth of the rice blast fungus colony on the ninth day of growth(P<0.05,the same below),the other four metabolites had no significant effect on the growth of the rice blast fungus colony(P>0.05). Six kinds of primary metabolites of rice had inhibitory effect on sporulation of M.oryzae,among which tyramine and α-pinene had the most obvious inhibitory effect. Dopamine hydrochloride significantly inhibited the spore germination of M.oryzae,while the other five metabolites had no obvious effect on the spore germination ofM.oryzae.Six kinds of primary metabolites of rice could significantly promote the growth of germ tube ofM.oryzae. Dopamine hydrochloride and L-tryptophan promoted appressorium formation,while L-glutamine and tyramine inhibited appressorium formation. Six kinds of primary metabolites in rice reduced the symptoms and disease index of rice blast at 36 and 48 h after inoculation with M.oryzae,among which dopamine hydrochloride,tyramine and galactitol had the best control effect on rice blast. The control effect of the six kinds of primary metabolites on rice blast at 48 h was higher than that at 36 h. Further studies found that dopamine hydrochloride and galactitol inhibited the expression of jasmonic acid(JA)signaling genes OsCOI1aOsCOI1b and OsMYC2 in rice at 36 and 48 h of rice blast fungus infection,but the JA repressor gene OsJAZ9 was up-regulated and induced ROS-related genes OsRbohBOsRbohA and the disease-related genes OsPR10aOsPR5 were up-regulated. Among them,the expression levels of ROS-related genes and disease course-related genes in rice induced by the two metabolites at 48 h of M.oryzae infection were higher than those in infected rice at 36 h after M.oryzae. Both metabolites inhibited JA signaling genes. Dopamine hydrochloride induced obvious increase in POD activity and a certain degree of increase in ROS content in rice at 36 and 48 h of M.oryzae infection.【Conclusion】Metabolites can improve rice blast resistance of susceptible rice variety through affecting the morphological development of rice blast fungus,inducing the expression of defense-related genes and increasing POD activity in susceptible rice. Therefore,the six metabolites have potential applications in the green control of rice blast disease.

     

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