Histone deacetylase gene SlHDA3 is involved in drought and salt response in tomato

Histone deacetylation, one of the vital modifying factors of post-translational modifications, is catalyzed by histone deacetylase. The genes of histone deacetylase (HDACs) play critical roles in responses to various stress. However, the detailed functions of most SlHDAC members in tomato remain unknown. In this work, we found that a histone deacetylase, SlHDA3, is involved in the response to NaCl and drought abiotic stresses. The expression of SlHDA3 was also induced significantly by NaCl, drought stress and hormone treatments. Upon silencing of SlHDA3 in tomato, the RNAi transgenic plants presented depressed tolerance to drought and salt stresses compared with Wild-type (WT) tomato. The results of the sensitivity experiment analysis indicated that the length of hypocotyl and root in RNAi plants were more inhibited by ABA and salt stress compared to those in WT plants at the post-germination stage. More serious growth status was exhibited in SlHDA3 transgenic plants under salt and drought stress, as evaluated by a series of physiological parameters related to stress responses, such as decreased Survival ratio (RWC), survival rate, Abscisic acid (ABA) content, chlorophyll content and Catalase (CAT) activity, and increased Malondialdehyde (MDA) and proline contents. In addition, the expression analysis of transgenic plants by quantitative reverse transcription-PCR (qRT-PCR) showed that the transcripts of genes associated with responses to abiotic stress were down-regulated under salt-stressed conditions. In summary, SlHDA3 acts as a stress-responsive gene, plays a role in the positive regulation of abiotic stress tolerance, and may be one of the new target genes in the engineering breeding of salt- and drought-tolerant tomato.