Expression of the Medicago truncatula MtDof32 transcription factor regulates plant growth and enhances abiotic stress tolerances in transgenic Arabidopsis

The DNA-binding one Zinc Finger (Dof) protein is an important transcription factor unique in plants, which plays important roles in regulating plant biological rhythm, flowering and nitrogenium storage. In this study, the MtDof32 gene was isolated from Medicago truncatula and the gene function was characterized in trangenic plants. The expression pattern exhibited that MtDof32 gene might be involved in stress responses and tolerances. Transgenic Arabidopsis thaliana plants were obtained by agrobacterium tumefaciens-mediated transformation. Compared with wild-type plants, the MtDof32 transgenic Arabidopsis showed reduced total branch number by 40 % on average, and increased rosettes number, the number gap was growing with plant growth. These phenotypes have never been found in previous studies. In addition, transgenic plants also showed delayed flowering, enlarged flower and leaf organs, and enhanced tolerances to osmotic and salt stresses. The expression level of some branching and flowering regulation genes in transgenic plants changed significantly, compared to those of wild-type plants. Taken together, these results demonstrated novel functions of MtDof32 in reducing branch number and increasing rosettes number, which is beneficial for further studies about the plant growth and development regulation network mediated by Dof protein family.