Preliminary Study In NAC Transcription Factors Of Medicago Falcata L.

NAC transcription factors belong to a great transcription factor family which is endowed with multiple biological functions, and only found in higher terrestrial plants. They are shown to involve in the variety kinds of biological reaction processes of plants, such as growth, hormone response, and adversity stress. Although the NAC genes of many plants have been cloned and explored in recent years, little research has been conducted on the NAC transcription factors of Medicago. In this research, the transcriptome sequencing of Medicago falcata L. was performed. Then the NAC transcription factors were screened based on the data obtained. Afterwards, the ten NAC protein sequences for Medicago falcata L. were randomly selected to construct the phylogenetic tree. Furthermore, the bioinformatics analysis was further carried out to research the characteristics of the tree. The results were included as follows:1) The phylogenetic tree was constructed as follows:At first, the multiple sequence alignment between the 10 NAC proteins for Medicago falcata L. and 85 NAC proteins sourced from TFDB for Medicago truncatula, was conducted. And then, the phylogenetic tree was constructed. The results revealed that 95 NAC transcription factors of Medicago can be divided into five categories (I-V). The compared NAC transcription factors of Medicago falcata L. and Medicago truncatula exhibit high homogeneity2) For the amino acid sequences for the NAC proteins of ten kinds of Medicago falcata L., their protein primary structure and physicochemical properties were analyzed and their protein secondary structure, conserved domains, motif, and tertiary structure were predicated. The predicated results showed that the ten kinds of Medicago falcata L. indicated preferable consistency between the secondary and tertiary structures, and were found to all have NAM domain as the conserved domain. These findings were verified, which agreed with the structural characteristics of NAC transcription factors family:the DNA-binding domain highly conserved for the N-terminal and C-terminal fragments of the proteins presented diverse regions of transcriptional regulation.3)In this work, the length of the cDNA for the c78782_g3 gene cloned from the Medicago falcata L. was measured to be 911bp. In addition, hydrophilic proteins with 292 amino acid residues were encoded in total.The results obtained may lay a scientific foundation for the further research into regulating the growth and the stress resistance of Medicago falcata L. using NAC transcription factors.