Preliminary analysis of two NAC transcription factor expression patterns in Larix olgensis

Abstract

The NAC transcription factor family is plant-specific with various biological functions. However, there are few studies on the NAC gene involving coniferous species. Bioinformatics research and expression analysis of NAC genes in Larix olgensis can be used to analyse the function of the NAC gene in the future. Screening of excellent genetic materials and molecular breeding have been utilized to cultivate high-quality, stress-resistant larches. According to the transcriptome data for L. olgensis, the genes Unigene81490 and Unigene70699 with complete ORFs (open reading frames) were obtained by conserved domain analysis and named LoNAC1 and LoNAC2, respectively. The cDNAs of LoNAC1 and LoNAC2 were 1971 bp and 1095 bp in length, encoding 656 and 364 amino acids, respectively. The molecular weights of the proteins encoded by the two genes were predicted to be 72.61 kDa and 41.13 kDa, and subcellular localization analysis indicated that the proteins were concentrated in the nucleus. The results of real-time quantitative PCR analysis showed that at different growth stages and in different tissues of L. olgensis, the relative expression levels of the two NAC genes were highest in the stem, and the expression differences were more obvious in non-lignified tissues. After drought, salt and alkali stress and hormone treatment, expression was induced to different degrees. The expression levels of LoNAC1 and LoNAC2 in semi-lignified L. olgensis were higher than in the other two periods (non-lignified and lignified), and expression levels significantly increased under drought and salt stress. Relative expression levels changed under hormone treatment. It is speculated that these two genes may not only be related to drought and salt stress and secondary growth but may also be induced by hormones such as abscisic acid. Overall, LoNAC1 and LoNAC2 are genetic materials that can be used for molecular breeding of larch.