Genome-wide identification, phylogenetic classification of histone acetyltransferase genes, and their expression analysis in sugar beet (Beta vulgaris L.) under salt stress.

ABSTRACT

MAIN CONCLUSION: This study identified seven histone acetyltransferase-encoding genes (HATs) from Beta vulgaris L. (sugar beet) genome through bioinformatics tools and analyzed their expression profiles under salt stress. Sugar beet HATs are phylogenetically divided into four families GNAT, MYST, CBP, and TAFII250. The BvHAT genes were differentially transcribed in leaves, stems, and roots of B. vulgaris salt-resistant (Casino) and -sensitive (Bravo) cultivars under salt stress. Histone acetylation is regulated by histone acetyltransferases (HATs), which catalyze ɛ-amino bond formation between lysine residues and acetyl groups with a cofactor, acetyl-CoA. Even though the HATs are known to participate in stress response and development in model plants, little is known about the functions of HATs in crops. In sugar beet (Beta vulgaris L.), they have not yet been identified and characterized. Here, an in silico analysis of the HAT gene family in sugar beet was performed, and their expression patterns in leaves, stems, and roots of B. vulgaris were analyzed under salt stress. Salt-resistant (Casino) and -sensitive (Bravo) beet cultivars were used for gene expression assays. Seven HATs were identified from sugar beet genome, and named BvHAG1, BvHAG2, BvHAG3, BvHAG4, BvHAC1, BvHAC2, and BvHAF1. The HAT proteins were divided into 4 groups including MYST, GNAT (GCN5, HAT1, ELP3), CBP and TAFII250. Analysis of cis-acting elements indicated that the BvHAT genes might be involved in hormonal regulation, light response, plant development, and abiotic stress response. The BvHAT genes were differentially expressed in leaves, stems, and roots under control and 300 mM NaCl. In roots of B. vulgaris cv. Bravo, the BvHAG1, BvHAG2, BvHAG4, BvHAF1, and BvHAC1 genes were dramatically expressed after 7 and 14 days of salt stress. Interestingly, the BvHAC2 gene was not expressed under both control and stress conditions. However, the expression of BvHAG2, BvHAG3, BvHAG4, BvHAC1, BvHAC2 genes showed a significant increase in response to salt stress in the roots of cv. Casino. This study provides new insights into the potential roles of histone acetyltransferases in sugar beet.