NPR1 paralogs of Arabidopsis and their role in salicylic acid perception.

María José Castelló,Julián Lamilla,Laura Medina-Puche,Pablo Tornero,Hua Lu

doi:10.1371/journal.pone.0209835

Abstract

Salicylic acid (SA) is responsible for certain plant defence responses and NON EXPRESSER OF PATHOGENESIS RELATED 1 (NPR1) is the master regulator of SA perception. In Arabidopsis thaliana there are five paralogs of NPR1. In this work we tested the role of these paralogs in SA perception by generating combinations of mutants and transgenics. NPR2 was the only paralog able to partially complement an npr1 mutant. The null npr2 reduces SA perception in combination with npr1 or other paralogs. NPR2 and NPR1 interacted in all the conditions tested, and NPR2 also interacted with other SA-related proteins as NPR1 does. The remaining paralogs behaved differently in SA perception, depending on the genetic background, and the expression of some of the genes induced by SA in an npr1 background was affected by the presence of the paralogs. NPR2 fits all the requirements of an SA receptor while the remaining paralogs also work as SA receptors with a strong hierarchy. According to the data presented here, the closer the gene is to NPR1, the more relevant its role in SA perception.

Highlights

Plants use several pathways for their defence against pathogens
In order to check if there was any NON EXPRESSER OF PATHOGENESIS RELATED 1 (NPR1)-like activity, our readout was the expression of the PR1 protein [42]
S1a Fig shows the immunodetection of PR1 after the transient expression of the Green Fluorescence Protein (GFP) fused to the NPRs, while the bottom shows the level of the GFP-NPRs as a control

Summary

Introduction

Plants use several pathways for their defence against pathogens. Broadly speaking, necrotrophic pathogens are dealt with by the methyl jasmonate pathway (MeJA, [1]), while biotrophic pathogens are resisted by means of the salicylic acid pathway (SA, [2]), with examples of positive and negative interactions between both pathways [3].NON EXPRESSER OF PATHOGENESIS RELATED 1 (NPR1) is an important SA perception gene. Plants use several pathways for their defence against pathogens. Necrotrophic pathogens are dealt with by the methyl jasmonate pathway (MeJA, [1]), while biotrophic pathogens are resisted by means of the salicylic acid pathway (SA, [2]), with examples of positive and negative interactions between both pathways [3]. NON EXPRESSER OF PATHOGENESIS RELATED 1 (NPR1) is an important SA perception gene. When mutants of Arabidopsis thaliana (Arabidopsis) were found that did not recognize SA or its analogues, the results were three alleles of NO RESPONSE TO BTH 4 (NRB4, [4]), and more than fifty alleles of NPR1 [5,6,7,8,9].

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Results

Conclusion