Molecular Genetics and Biosynthesis of Loline Alkaloids by Mutualistic Endophystes

9808554 Schardl植物对昆虫的防御包括称为生物碱的各种含氮化学物质。 在具有共生真菌内生菌的禾本科植物中，内生菌产生几种重要的抗昆虫生物碱，从而保护禾本科植物免受草食性昆虫的侵害。 该项目的重点是黑麦草碱，真菌生物碱是独特的草内生菌系统，高度杀虫，异常丰富。 基于内生菌是黑麦草碱的来源这一发现，将进行黑麦草碱生物碱生产的生物化学和遗传学研究。 首先，将改进培养方法以诱导或抑制黑麦草的真菌表达。 利用这些方法，将确定拟议的黑麦草碱生物碱前体的具体命运。 最后，将基于在表达和不表达黑麦草碱生物碱条件下表达的差异来鉴定可能编码黑麦草碱生物合成途径中的步骤的基因。 这项工作将促进对次生代谢物的生物合成的理解，这些次生代谢物在植物的生物保护中起着重要作用，并且在植物和有益微生物之间的生态相互作用中起着重要作用。 对社会的一个可能的应用惠益将是在农业和园艺中更加知情和广泛地使用生物植物保护系统，帮助减少使用破坏生态的化学品和做法。

9808554 Schardl The defenses of plants against insects include diverse nitrogen-containing chemicals called alkaloids. In grasses that possess symbiotic fungal endophytes several important anti-insect alkaloids are produced by the endophytes, which thereby protect the grass plants from herbivorous insects. This project focuses on the lolines, fungal alkaloids that are unique to grass-endophyte systems, highly insecticidal, and exceptionally abundant. building on the finding that the endophyte is the source of lolines, the biochemistry and genetics of loline alkaloid production will be conducted. First, culture methods will be refined to induce or suppress fungal expression of lolines. Making use of these methods, the specific fate of proposed loline alkaloid precursors will be determined. Finally, genes that may code for steps in the biosynthetic pathway to lolines will be identified based on differences in expression under loline alkaloid-expressing and non-expressing conditions. This work will advance understanding of the biosynthesis of secondary metabolites that play important roles in biological protection of plants from their pests, and in ecological interactions between plants and beneficial microorganisms. A likely applied benefit to society will be more informed and widespread use of biological plant protection systems in agriculture and horticulture, helping reduce the use of ecologically damaging chemicals and practices.