Pleiotropic effects of TaMYB3R1 on plant development and response to osmotic stress in transgenic Arabidopsis.

In a previous study, we isolated and characterized TaMYB3R1, a MYB3R gene, from wheat (Triticum aestivum L.). In vitro assays showed that the TaMYB3R1 protein is localized to the nucleus, and functions as an MSA-binding transcriptional activator. Expression of TaMYB3R1 is induced by exogenous abscisic acid (ABA) and abiotic stress, which encouraged us to further investigate its function in planta. In the present study, we generated transgenic Arabidopsis plants overexpressing TaMYB3R1. Compared with wild-type plants, the transgenic lines produced more rosette leaves, and thus more inflorescences, but the plants showed delayed development at the reproductive stage. The TaMYB3R1 protein also functions in the osmotic stress response. Transgenic Arabidopsis plants showed enhanced tolerance to drought and salt stresses, and the tolerance phenotype was conveyed by limiting transpiration through increasing stomatal closure as well as reducing water loss. In addition, TaMYB3R1 influenced the expression of both ABA-dependent and ABA-independent responsive genes, implicating TaMYB3R1 in diverse osmotic stress-response mechanisms in Arabidopsis. Our study sheds light on novel functions of a plant MYB3R protein.