The function of AHG2/AtPARN in biotic and abiotic stess responses

Abstract

The phytohormone abscisic acid (ABA) regulates physiologically important stress and developmental responses. To address the mechanism of ABA response, we isolated 4 novel ABA hypersensitive mutants named ahg (ABA hypersensitive germination). ahg2 showed clear ABA hypersensitivity not only in germination but also at later developmental stages. Map-based cloning of AHG2 revealed that this gene encodes a poly(A)-specific ribonuclease (AtPARN). Interestingly, the expression mRNA levels of stress- and salicylic acid-inducible genes in ahg2 were upregulated compared to WT. ahg2 also showed SA hypersensitivity in germination and resistance against biotrophic pathogen P. syringae pv. tomato but not against necrotrophic pathogen B. cinerea in plant. In addition, ahg2 plant accumulated more SA as well as ABA. We will discuss the role of AHG2/AtPARN in abiotic stress and biotic stress.