Application of a fast-forward genetic tool to identify plant genes involved in the perception of coronatine, a phytotoxin produced by Pseudomonas syringae pv. tomato DC3000

Abstract

Scope and Method of Study: The purpose of this study was to identify host factors that are involved during the interaction of the phytopathogen Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) and host plants. The specific objectives of this project were to: (i) screen Nicotiana benthamiana lines silenced with a N. benthamiana cDNA library for altered chlorosis in response to the phytotoxin coronatine (COR); and (ii) further characterize the identified genes from tomato and Arabidopsis, which are hosts infected by Pst DC3000. Another purpose of this study was to (iii) develop a high-throughput tomato seedling assay that could be used for screening of Pst DC3000 virulence mutants.

Findings and Conclusions: Objective I. Several plant genes were identified with potential roles in COR-induced chlorosis. One of the genes, ALC1, was further characterized on tomato and Arabidopsis and found to be involved in COR/Pst DC3000-mediated chlorosis. Furthermore, genetic analysis suggested that the gene is involved in the regulation of Pst DC3000-induced senescence in Arabidopsis. Objective II. A high-throughput tomato seedling assay was developed and optimized. The assay was validated using well-characterized Pst DC3000 virulence mutants and compared with results previously obtained using mature tomato plants.