State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, Harbin, 150040, China.
BMC Plant Biol. 2024 Sep 28;24(1):881. doi: 10.1186/s12870-024-05619-y.
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.
LoNAC3 with complete cds was identified and isolated from the cDNA of Larix olgensis based on transcriptome data. The cDNA length of LoNAC3 is 1185 bp, 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 at different growth stages and in different tissues of L. olgensis, the relative expression level of LoNAC3 was highest in the needles. After drought, salt, alkali stress and hormone treatment, expression was induced to different degrees. The expression level of LoNAC3 was significantly increased under drought and salt conditions. The relative expression level changed under methyl jasmonate (MeJA) and abscisic acid (ABA) treatment. 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, LoNAC3 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.
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.
落叶松是一种重要的用材树种。传统的树木遗传育种方法进展缓慢，有必要开展基因功能分析和遗传改良育种研究。NAC 转录因子家族是一类具有多种生物学功能的植物特异性转录因子家族，最近的研究表明了这一点。然而，在裸子植物针叶树物种中，关于 NAC 基因的研究较少。
根据转录组数据，从落叶松 cDNA 中鉴定并分离出全长 cds 的 LoNAC3。LoNAC3 的 cDNA 长度为 1185bp，编码 394 个氨基酸，在 N 端具有保守的 NAM 结构域，亚细胞定位于细胞核。实时定量 PCR 分析结果表明，在落叶松不同生长阶段和不同组织中，LoNAC3 的相对表达水平在针叶中最高。在干旱、盐、碱胁迫和激素处理后，表达水平被不同程度地诱导。在干旱和盐胁迫下，LoNAC3 的表达水平显著增加。茉莉酸甲酯（MeJA）和脱落酸（ABA）处理后相对表达水平发生变化。通过观察过表达 LoNAC3 烟草的表型，发现过表达烟草比野生型烟草更矮，开花更早。在非生物胁迫下，LoNAC3 过表达烟草的发芽率较低，生长状态较差。胁迫处理的转基因烟草的丙二醛（MDA）含量高于野生型烟草，而过氧化物酶（POD）活性低于野生型烟草。
通过对 LoNAC3 序列和启动子表达的分析，可以得出结论，LoNAC3 参与了落叶松的干旱和盐胁迫响应过程，并且受到 ABA 和 MeJA 表达的诱导。过表达 LoNAC3 导致烟草生长受阻，并通过活性氧途径负调控其对干旱和盐胁迫的耐受性。对 LoNAC3 的表达模式和功能的初步分析可以为后期落叶松的遗传改良提供理论基础和优质材料。
