Histone Deacetylase 6 (HDA6) Are Involved in The Down-Regulation of Jasmonic Acid (JA) Responses Produced by Low Red/Far-Red (R:FR) Ratios in Arabidopsis

CERRUDO IGNACIO; BALLARÉ CARLOS L.

Cordoba

Congreso; 16th International Congress on Photobiology; 2014

International Union of Photobiology

In response to damage or herbivory, plants rapidly accumulate the hormone JA, which activates defense responses [5]. When plants perceive low R:FR ratios, a signal of proximity of competitors, they activate the expression of the shade-avoidance syndrome. Studies have shown that low R:FR down-regulate JA responses [1; 2]. For example, JA-induced up-regulation of the transcription factor ERF1, and its target gen PDF1.2, are suppressed in low R:FR [6; 3]. Posttranslational modifications of histones, including acetylations, play a key role in gene activity. Histone acetylation is modulated through the action of histone acetyl transferases and HDAs. The HDAs have been implicated in the regulation of JA signaling in Arabidopsis [4], and recent work suggested that JAZ proteins recruit HDA6 to repress the JA-ET signaling [6]. Here, we show that in plants treated with an inhibitor of HDAs (Trichostatin A), low R:FR failed to down-regulate the expression of ERF1 and PDF1.2. Bioassays with Botrytis cinerea in HDA6 mutant plants (axe1-4; axe1-5) showed that, in contrast to wild-type plants, these mutants do not respond to low R:FR ratios with increased susceptibility to fungal infection. These mutants also fail to down-regulate anthocyanin accumulation in low R:FR. We propose that HDA6-mediatd changes in the chromatin structure are involved in the down-regulation of the JA responses in plants grown under low R:FR ratios