Genome-wide association study reveals novel regulators of defense hormonal crosstalk in Arabidopsis thaliana
S. PROIETTI (1), S. Coolen (1), L. Caarls (1), S. Van Wees (1), C. Pieterse (1) (1) Utrecht University, Netherlands

The jasmonic acid (JA) pathway plays an important role in the regulation of plant defense against necrotrophic pathogens and insect herbivores. Salicylic acid (SA) and abscisic acid (ABA) have been shown to interact with the JA pathway, resulting in strong effects on the defense output. Several molecular players of SA/JA and ABA/JA crosstalk have been identified, but many missing links remain elusive. To identify new regulators of SA/JA and ABA/JA crosstalk, we performed a genome-wide association (GWA) study on natural genetic variation in Arabidopsis for the effect of SA and ABA on JA pathway. Firstly, 349 wild Arabidopsis accessions were treated with MeJA, ABA+MeJA or SA+MeJA after which the level of expression of the JA marker gene PDF1.2 was quantified. The results showed that Arabidopsis has a large genetic variation in the magnitude by which SA and ABA affect JA-responsive gene expression. GWA mapping of the gene expression data revealed genomic regions that are potentially associated with SA/JA or ABA/JA crosstalk. Underlying candidate genes are involved in regulatory as well as metabolic pathways, signal transduction, transporter activity and oxidative stress. The role of 6 candidate genes in SA/JA crosstalk and of 12 candidate genes in ABA/JA crosstalk was confirmed using T-DNA insertion lines. Future research will be focused on unraveling their mode of action in hormonal interplay, which will help to better understand the way plants react to combinatorial stress.

Abstract Number: P16-467
Session Type: Poster