Isolation and Expression Pattern Analysis of Larix olgensis LoNAC5: LoNAC5 Acts as a Positive Regulator of Drought and Salt Tolerance

NAC transcription factors are a kind of plant specific transcription factor widely distributed in plants, and they play an important role in the process of plant growth and development. According to the transcriptome data, a transcription factor with typical NAC characteristics was isolated from <i>Larix olgensis</i> (common name "Dahurian larch"), that we named <i>LoNAC5</i>. The length of the coding sequence (CDS) was 1164 bp, encoding 387 amino acids. The LoNAC5 protein harbors a NAM (NAC family) domain at the 14-139 aa region of its N-terminus and an activation domain at the 324-364 aa region of the C-terminus. Phylogenetic tree analysis revealed that <i>LoNAC5</i> belonged to the ATNAC3 subgroup. Cis-acting element analysis showed that there were multiple plant stress-resistance-related elements on the promoter of <i>LoNAC5</i>, including hormone and light responsiveness elements. <i>LoNAC5</i> was localized in the nucleus by injection transformation of tobacco leaves. Results suggested that the LoNAC5 protein is active as a homodimer and that it binds to the GATGTG motif. The results of RT-qPCR showed that <i>LoNAC5</i> is a highly expressed gene in <i>L. olgensis</i>, and the expression level is highest in 180-day needles. <i>LoNAC5</i> responded to various hormone treatments and was induced by drought and salt stress. The yeast phenotype test showed that overexpression of <i>LoNAC5</i> could make yeast grow better under drought and salt stress. It was speculated that <i>LoNAC5</i> might act in <i>L. olgensis</i> as a positive regulator of drought and salt tolerance.