Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
Plant Signal Behav. 2011 Jul;6(7):919-23. doi: 10.4161/psb.6.7.15304.
Plants accumulate a great diversity of natural products, many of which confer protective effects against phytopathogenic attack. Earlier we had demonstrated that the leaf extracts of Zizyphus jujuba and Ipomoea carnea inhibit the in vitro mycelial growth of Rhizoctonia solani, and effectively reduce the incidence of sheath blight disease in rice. Here we demonstrate that foliar application of the aqueous leaf extracts of Z. jujuba and I. carnea followed by challenge inoculation with R. solani induces systemic resistance in rice as evident from significantly increased accumulation of pathogenesis-related proteins such as chitinase, β-1,3-glucanase and peroxidase, as well as defense-related compounds such as phenylalanine ammonia-lyase and phenolic substances. Thin layer chromatographic separation of secondary metabolites revealed presence of alkaloid and terpenoid compounds in the leaf extracts of Z. jujuba that exhibited toxicity against R. solani under in vitro condition. Thus, the enhanced sheath blight resistance in rice seedlings treated with leaf extracts of Z. jujuba or I. carnea can be attributed to the direct inhibitory effects of these leaf extracts as well as their ability to elicit systemic resistance against R. solani.
植物积累了大量的天然产物，其中许多具有抵御植物病原物攻击的保护作用。我们之前已经证明，酸枣和番薯的叶提取物可以抑制丝核菌的体外菌丝生长，并有效降低水稻纹枯病的发病率。在这里，我们证明了在叶面喷施酸枣和番薯的水提叶提取物，然后用丝核菌进行挑战接种，可以诱导水稻产生系统抗性，如几丁质酶、β-1,3-葡聚糖酶和过氧化物酶等与发病相关的蛋白质以及苯丙氨酸解氨酶和酚类物质等防御相关化合物的积累明显增加。次生代谢产物的薄层色谱分离表明，酸枣叶提取物中存在生物碱和萜类化合物，这些化合物在体外条件下对丝核菌表现出毒性。因此，用酸枣或番薯叶提取物处理的水稻幼苗中增强的纹枯病抗性可以归因于这些叶提取物的直接抑制作用以及它们诱导对丝核菌产生系统抗性的能力。
