Epigenetic Chromatin Modifiers in Barley: II. Characterization and Expression Analysis of the HDA1 Family of Barley Histone Deacetylases During Development and in Response to Jasmonic Acid

Epigenetic regulation of gene expression plays an important role in various aspects of eukaryotic development and is associated with modifications of chromatin structure. These are accomplished, in part, through the reversible process of histone acetylation/deacetylation, catalyzed by histone acetyltransferases (HATs), and histone deacetylases (HDACs), respectively. Eukaryotic HDACs are grouped in three major families, RPD3/HDA1 (thereafter cited as HDA1), SIR2 and the plant-specific HD2. Histone deacetylase genes have been studied in Arabidopsis and rice, but little is known about these genes from important crop plants. In this work, cDNAs encoding members of the HDA1 family and representing all four classes, Class I, Class II, Class III, and Class IV, were isolated and characterized from barley (Hordeum vulgare), a cereal crop of high agronomic importance. Expression analysis of the barley HDA1 family genes, HvHDAC1-I-1, HvHDAC1-I-3, HvHDAC1-II-1, HvHDAC1-III-1, and HvHDAC1-IV-1 demonstrated that they are expressed in all tissues and seed developmental stages examined. Differences in transcript abundance both in vegetative and reproductive tissues were observed among the different genes suggesting functional diversification of the HDA1 members. Differential expression was also evidenced for some of the HDA1 genes in two barley cultivars differing in various characteristics, such as seed size and resistance to stress, implying a possible association of these genes with different traits. Furthermore, the HDA1 genes were found to respond to the stress-related hormone jasmonic acid (JA), suggesting an association of these genes with barley responsiveness to biotic and abiotic stress. The expression pattern of the HDA1 genes suggests possible roles in the epigenetic regulation of barley development and stress response.