Biosynthesis and functional analysis of the COR-like metabolites produced by the common scab pathogen Streptomyces scabies

Li, Yuting (2015) Biosynthesis and functional analysis of the COR-like metabolites produced by the common scab pathogen Streptomyces scabies. Masters thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (2MB)

Abstract

Streptomyces scabies is a Gram-positive soil bacterium that causes common scab disease, which is identified by the round corky lesions that form on the surface of root and tuber crops such as potatoes. Virulence factors that contribute to the plant pathogenic phenotype of S. scabies include the phytotoxic secondary metabolite thaxtomin A and the secreted necrogenic protein Nec1. In addition, S. scabies produces a family of secondary metabolites called the COR-like metabolites, which are structurally similar to the COR (coronatine) phytotoxin produced by the bacterial plant pathogen Pseudomonas syringae. The goal of this thesis research was to characterize the biosynthesis and function of the S. scabies COR-like metabolites. In the first research chapter, the role of three genes, scab79711, cfa8 and scab79691, in metabolite biosynthesis was elucidated by constructing gene deletion mutants in S. scabies and assessing the effect of each deletion on the production of the COR-like metabolites. In the second research chapter, the bioactivity of the COR-like metabolites was investigated by testing S. scabies culture supernatants or extracts containing the metabolites in various plant bioassays. In addition, the bioactivity of the primary COR-like metabolite, coronafacoyl-L-isoleucine, was tested alongside equimolar amounts of COR in order to compare the relative toxicity of the two metabolites. The results of this study provide important insight into the biosynthetic pathway responsible for COR-like metabolite production in S. scabies as well as the role of the metabolites in S. scabies plant pathogenicity. Future directions for this research were discussed.

Actions (login required)

View Item