Evaluation of alternative IAA biosynthetic pathways in the bacteria from the pseudomonas syringae complex
Pintado Calvillo, Adrián,Pérez-Martínez, Isabel,Cerezo, Miguel,Flors, Víctor,Ramos-Rodríguez, Cayo Juan
- Published
- 2017-07-02
- Language
- en
Abstract
Indole-3-acetic acid (IAA) is a phytohormone belonging to the auxin group which production is widely distributed among plant-associated bacteria. In phytopathogenic bacteria, several IAA biosynthetic pathways have been described. The best characterized is the indole-3-acetamide (IAM) pathway, where tryptophan is initially converted into IAM by a monooxygenase (iaaM gene), and later transformed to IAA in a reaction catalysed by a hydrolase (iaaH gene). Pseudomonas savastanoi pv. savastanoi NCPPB 3335 (Psv), which synthesizes IAA through IAM, encodes two paralogs of these two genes organized in two operons (iaaMH-1 and iaaMH-2). Previously, we have demonstrated that a Psv mutant in the iaaMH-1 operon produces an amount of IAA significantly lower than that synthesized by the wild type strain. This strain, shows a reduced virulence in olive plants. In contrast, a mutant in the iaaMH-2 operon (which encodes a iaaM-2 pseudogene), produces IAA levels similar to those of the wild type strain and is not affected in virulence. Unexpectedly, the iaaMH-1 mutant and the double mutant iaaMH- 1/iaaMH-2 synthesize a residual amount of IAA, suggesting the existence of an alternative route for the production of this compound in Psv.
Full text
17/7/17 16&24Abstract detail Página 1 de 1file:///Users/adrianpintado/Desktop/Abstract%20detail.html Scientific programme PV12 Poster Viewing Pathogens / Pathogenicity - Part III 12-Jul-2017 10:30 17:00 Abstract: 334 EVALUATION OF ALTERNATIVE IAA BIOSYNTHETIC PATHWAYS IN THE BACTERIA FROM THE PSEUDOMONAS SYRINGAE COMPLEX Backgrounds Indole-3-acetic acid (IAA) is a phytohormone belonging to the auxin group which production is widely distributed among plant-associated bacteria. In phytopathogenic bacteria, several IAA biosynthetic pathways have been described. The best characterized is the indole-3-acetamide (IAM) pathway, where tryptophan is initially converted into IAM by a monooxygenase (iaaM gene), and later transformed to IAA in a reaction catalysed by a hydrolase (iaaH gene). Pseudomonas savastanoi pv. savastanoi NCPPB 3335 (Psv), which synthesizes IAA through IAM, encodes two paralogs of these two genes organized in two operons (iaaMH-1 and iaaMH-2). Previously, we have demonstrated that a Psv mutant in the iaaMH-1 operon produces an amount of IAA significantly lower than that synthesized by the wild type strain. This strain, shows a reduced virulence in olive plants. In contrast, a mutant in the iaaMH-2 operon (which encodes a iaaM-2 pseudogene), produces IAA levels similar to those of the wild type strain and is not affected in virulence. Unexpectedly, the iaaMH-1 mutant and the double mutant iaaMH1/iaaMH-2 synthesize a residual amount of IAA, suggesting the existence of an alternative route for the production of this compound in Psv. Objectives Identification of the alternative IAA biosynthetic pathway active in the Psv mutant devoid of the IAM pathway. Determination of the IAA biosynthetic pathway encoded by other strains of the P. syringae complex with different host spectrum. Methods Candidate genes search, directed mutagenesis and functional analysis. Conclusions Besides the IAM pathway, bacteria from the P. syringae complex encode other pathways for the biosynthesis of IAA. Co-authors A. Pintado 1, I. Pérez-Martínez 1, M. Cerezo 2, V. Flors 2, C. Ramos 1 1Universidad de Málaga, Biología CelularGenética y Fisiología Animal, Málaga, Spain 2Universitat Jaume I, Departament de Ciències Agràries i del Medi Natural, Castelló de la Plana, Spain << Back to session