Elongator mediates ABA responses, oxidative stress resistance and anthocyanin biosynthesis in Arabidopsis

Elongator is a histone acetyl-transferase complex consisting of six subunits, and is highly conserved in eukaryotic organisms. Here, we isolated two novel mutants, elp2 and elp6, during a genetic screening for ABA-hypersensitive Arabidopsis mutants. Map-based cloning identified ELP2 and ELP6, which encode the orthologs of the yeast Elongator subunits, ELP2 and ELP6, respectively. Another Elongator subunit mutant, elp4/elo1, was obtained from the SALK T-DNA collection. The elp1/abo1/elo2 mutant was isolated in a previous study. All four of the Elongator mutants had narrow leaves, reduced root growth, ABA hypersensitivity and an increased accumulation of anthocyanins. Mutations in the core subcomplex subunits ELP1/ABO1 and ELP2, but not in the accessory subcomplex subunits ELP4/ELO1 and ELP6, caused stomatal closing to be supersensitive to ABA. In addition, the four mutants were all more resistant than the wild type to oxidative stress produced by methyl viologen, and to CsCl. Gene expression analysis indicated that the four mutants had increased transcript levels of CAT3 under normal conditions, increased transcript levels of ZAT10 when treated with ABA and reduced transcript levels of MYBL2, which encodes a single-repeat MYB protein, acting as a negative regulator of anthocyanin biosynthesis. Our results suggest that Elongator plays crucial roles in regulating plant responses to ABA, oxidative stress resistance and anthocyanin biosynthesis in Arabidopsis.