Study On The Characteristic Of MfNAC34 Gene In Medicago Falcata

Medicago falcata exhibits a greater tolerance against cold,salt and drought stresses,and it is an excellent germplasm resource and important gene pool for breeding and improvement of leguminous herb.Several studies have demonstrated that the NAC transcription factor family genes play significant roles in regulating plant growth,development and responding to the stresses.Based on a cDNA sequence obtained from wild Medicago falcata in our laboratory,the complete amino acids sequence of coded protein was derived.The coded protein comprised 206 amino acids,and the putative NAM domain was found form the9 to 142 amino acids positions.Then the cDNA was named as MfNAC34 gene because the sequence alignment indicated that the deduced protein shared the highest identity with Medicago truncatula MtNAC34.The MfNAC34,with a predicted molecular mass of 23.52 kDa and an isoelectric point of 4.24,was predicted as a kind of hydrophilic protein without signal peptide and transmembrane domain,and maybe locate to the cell nucleus.Then,the localization of MfNAC34 in the cell nucleus was assessedand confirmed by a confocal microscope after transient expression of MfNAC34-sGFP in tobacco(Nicotiana Benthamiana)epidermal cell.It was confirmed that the MfN-AC34 play a role of transcriptional activation in yeast cell and the transcriptional activation domain was located at the Cterminal of MfNAC34 protein.The expression level of MfNAC34 in stems was prominently higher than in roots and leaves.At the sa-me time,the expression of MfNAC34 was regulated by salt,drought and cold stresses in roots,stems and leaves of wild Medicago falcata.These findings indicate that the MfNAC34 may play an important role in responding to the salt,drought and cold stresses in wild Medicago falcata.Meanwhile,the overexpression vector pPZP221(35-S-MfNAC34-NOS)was constructed and transformed into Arabidopsis thaliana via floral dipping method,and the T1 transgenic plants were confirmed by PCR analysis.After subculturing,the T3 transgenic plants were obtained,which can be used as preliminary material for further exploration of the function of MfNAC34 responding to the abiotic stresses.