beta-carbonic anhydrases play a role in salicylic acid perception in Arabidopsis

Abstract

[EN] The plant hormone salicylic acid (SA) is required for defense responses. NON EXPRESSER OF PATHOGENESIS RELATED 1 (NPR1) and NON RECOGNITION OF BTH-4 (NRB4) are required for the response to SA in Arabidopsis (Arabidopsis thaliana). Here, we isolated several interactors of NRB4 using yeast two-hybrid assays. Two of these interactors, beta CA1 and beta CA2, are beta-carbonic anhydrase family proteins. Since double mutant beta ca1 beta ca2 plants did not show any obvious phenotype, we investigated other beta CAs and found that NRB4 also interacts with beta CA3 and beta CA4. Moreover, several beta CAs interacted with NPR1 in yeast, including one that interacted in a SA-dependent manner. This interaction was abolished in loss-of-function alleles of NPR1. Interactions between beta CAs and both NRB4 and NPR1 were also detected in planta, with evidence for a triple interaction, NRB4-beta CA1-NPR1. The quintuple mutant beta ca1 beta ca2 beta ca3 beta ca4 beta ca6 showed partial insensitivity to SA. These findings suggest that one of the functions of carbonic anhydrases is to modulate the perception of SA in plants.