Isolation and functional analysis of the Larix olgensis LoNAC3 transcription factor gene

Abstract

Background Larch is an important timber tree species. The traditional methods of tree genetic breeding have been progressing slowly. It is necessary to carry out gene function analysis and genetically modified breeding research. The NAC transcription factor family is a plant-specific transcription factor family with various biological functions, as shown in recent research. However, there are few studies on the NAC gene among gymnosperm coniferous species. Results LoNAC3 with complete cds was identified and isolated from the cDNA of Larix olgensis based on transcriptome data. The cDNA length of LoNAC3 is 1185bp, encoding 394 amino acids, with a conserved NAM domain located at the N-terminus, and subcellular localization in the nucleus. The results of real-time quantitative PCR analysis showed that the relative expression level of LoNAC3 was higher in the needles of L. olgensis, and the response to salt and drought treatment was more obvious. In addition, LoNAC3 was induced to express by methyl jasmonate (MeJA) and abscisic acid (ABA). By observing the phenotype of overexpressed LoNAC3 tobacco, it was found that overexpressed tobacco is shorter and blooms earlier than wild-type tobacco. Under abiotic stress, overexpressed tobacco has lower germination rates and poorer growth status. Transgenic tobacco under stress treatment has a higher malondialdehyde (MDA) content than wild-type tobacco, while peroxidase (POD) activity is lower than wild-type tobacco. Conclusions Through the analysis of LoNAC3 sequence and promoter expression, it can be concluded that LoNAC3 is involved in the drought and salt stress response processes of L. olgensis, and is induced by ABA and MeJA expression. Overexpression of LoNAC3 leads to stunted tobacco growth and negatively regulates its tolerance to drought and salt stress through the reactive oxygen species pathway. The preliminary analysis of the expression pattern and function of the LoNAC3 can provide a theoretical basis and high-quality materials for genetic improvement of larch in later stages.