Molecular Characterization of Nine Tissue-Specific or Stress-Responsive Genes of Histone Deacetylase in Tomato (Solanum lycopersicum)

Histone acetylation and deacetylation play an important role in plant growth and development by chromatin modifications. Regulation of histone acetylation and deacetylation is controlled by histone acetyltransferases and histone deacetylases (HDACs) in different tissues and development stages. Knowledge of the importance of genome stability, transcriptional regulation, development and response to stress has been obtained from the model plant Arabidopsis. However, little information on biological functions and development or stress-related HDAC genes is available in tomato. In this study, nine tomato histone deacetylase genes of the RPD3/HDA1 subfamily, from SlHDA1-SlHDA9, were characterized to encode histone deacetylase proteins that share high similarity of protein sequences and conserved domains with those of known plant HDACs. These HDAC genes have been further subdivided into four groups, namely Class I, Class II, Class III and Class IV based on phylogenetic analysis. Quantitative RT-PCR analysis revealed that the nine SlHDAC genes were expressed in all tissues with different transcript abundance and exhibited different tissue-specific expression profiles, suggesting that they may have crucial and diverse roles in tomato growth and development. Varying degrees of induction were detected in the transcript levels of these SlHDACs under various abiotic stresses including NaCl, dehydration, and high/low temperature. These nine SlHDACs were induced by the above stresses with differential/similar induction levels. Overall, this study provides valuable information for further exploring the regulation of HDAC genes during tomato development and fruit ripening and in response to environmental stresses.