Expression profiling and characterization of a G-Box binding protein, B12Dg, from pearl millet

Objectives: This study aims to characterize the B12Dg from pearl millet and assess its expression in response to abiotic stress and plant hormones during germination. Methods: cDNA of B12Dg has been sequenced, the deduced protein has been characterized through in silico tools, and B12Dg expression has been examined after treatment by the plant hormones and under abiotic stresses. Results: The sequenced cDNA for PgB12Dg consisted of 314 base pairs and had an open reading frame of 261 base pairs encoded for 87 amino acids. The deduced PgB12Dg protein comprised a B12D domain from 7 to 74 amino acids and a transmembrane helix. Strong conservation was observed among the PgB12Dg protein and its orthologues from monocots. Transmembrane topology prediction and subcellular localization suggested that the deduced PgB12Dg protein accommodates transmembrane helix spanning from 10 to 32 amino acids embedded in the inner mitochondrion membrane. Expression analysis by real-time PCR indicated that PgB12Dg was upregulated in roots but downregulated in seeds from 3 day-old-seedlings under drought and cold stress. At the same time, no significant up or downregulation was shown under salt stress. Treatment by plant hormones showed upregulation by gibberellic acid and downregulation by abscisic acid in one-day-old germinated seeds. Conclusions: The regulation of PgB12Dg by plant hormones and abiotic stress in pearl millet during germination can help to understand the transcriptional regulation mechanisms of the PgB12Dg during plant growth under stress.