Type‐2 histone deacetylases as new regulators of elicitor‐induced cell death in plants

Abstract

Summary• Plant resistance to pathogen attack is often associated with a localized programmed cell death called hypersensitive response (HR). How this cell death is controlled remains largely unknown.• Upon treatment with cryptogein, an elicitor of tobacco defence and cell death, we identified NtHD2a and NtHD2b, two redundant isoforms of type-2 nuclear histone deacetylases (HDACs). These HDACs are phosphorylated after a few minutes' treatment, and their rate of mRNAs are rapidly and strongly reduced, leading to a 40-fold decrease after10 h of treatment.• By using HDAC inhibitors, RNAi-and overexpression-based approaches, we showed that HDACs, and especially NtHD2a ⁄ b, act as inhibitors of cryptogeininduced cell death. Moreover, in NtHD2a ⁄ b-silenced plants, infiltration with cryptogein led to HR-like symptoms in distal leaves.• Taken together, these results show for the first time that type-2 HDACs, which are specific to plants, act as negative regulators of elicitor-induced cell death in tobacco (Nicotiana tabacum), suggesting that the HR is controlled by posttranslational modifications including (de)acetylation of nuclear proteins.

Plant-Specific Histone Deacetylases HDT1/2 Regulate GIBBERELLIN 2-OXIDASE2 Expression to Control Arabidopsis Root Meristem Cell Number

“…However, the function of HDTs in root development has not been investigated. It has been shown that HDTs are involved in responses to biotic and abiotic stress (Sridha and Wu, 2006;Bourque et al, 2011;Ding et al, 2012;Luo et al, 2012), and they can repress the expression of defense-related genes by altering their chromatin acetylation status (Bourque et al, 2011;Ding et al, 2012). We studied whether HDTs regulate the switch from cell division to expansion and in this way contribute to the mechanisms controlling RM cell number and subsequently root growth.…”

Nitric Oxide Modulates Histone Acetylation at Stress Genes by Inhibition of Histone Deacetylases

“…In the case of HD1, phosphorylation changed the substrate specificity of the enzyme whereas dephosphorylation of HD2 resulted in the inactivation of this protein (Brosch et al, 1992;Lusser et al, 1997;Kölle et al, 1999). Recently, it was shown that NtHD2a and NtHD2b, both belonging to the plant-specific HDAC family, are rapidly phosphorylated after cryptogein treatment of tobacco (Nicotiana tabacum) suspension cells, but the precise function of this modification during the hypersensitive response remained elusive (Bourque et al, 2011).…”

“…Since reductive decomposition of GSNO results in the formation of GSH and, additionally, NO induces a rapid change in the glutathione state by activating the biosynthesis of GSH (Kovacs et al, 2015), a GSH treatment was included as an additional control to distinguish the direct effects of GSNO-released NO from those mediated by an increase of the GSH concentration, similar to a recently published study (Begara-Morales et al, 2014). As positive control, 5 mM trichostatin A (TSA) was applied, which is an inhibitor of RPD3-like HDACs and possibly HD-tuins (Yoshida et al, 1990;Bourque et al, 2011).…”

Le monoxyde d’azote

“…B. Réponse hypersensible : dans l'exemple présenté, des feuilles de tabac ont été infiltrées par la cryptogéine, une protéine produite par l'oomycète Phytophthora cryptogea qui déclenche une réponse immunitaire. La zone nécrotique, ou RH, témoigne de la mort des cellules directement en contact avec la cryptogéine [37]. Lors de l'établissement de la RH, les cellules qui n'ont pas été en contact avec la cryptogéine (tissus adjacents à la zone nécrotique ou distants de celle-ci) sont placées dans un état de veille défensive permettant à la plante de résister efficacement à une attaque ultérieure par Phytophthora cryptogea ou d'autres agents pathogènes.…”