Isolation of GsNAC20 Gene from Glycine soja and Its Response to Abiotic Stresses

Plant-specific transcription factor family NAC (NAM, ATAF1/2, CUC2) plays essential roles in various biological processes including development, senescence, morphogenesis, and stress signal transduction pathway. An NAC gene, which was designated GsNAC20 and showed 99% similarity to GmNAC20 (EU440353.1) from Glycine max, was isolated from G. soja using yeast one hybrid method. The GsNAC20 protein possesses a typical NAC DNA-binding domain at the N-terminal and a transcription activation region at the C-terminal. Like GmNAC20, GsNAC20 could bind to MYB1AT element (the core sequence of AAACCA) in vitro, but no transcriptional activation activity was detected in the yeast assay system. Using the transient expression system in tobacco epidermis cells, GsNAC20 was confirmed to be localized in nucleus. The expression of GsNAC20 was induced by drought, low temperature and salt stress, and the expression patterns were different in leaf and root of G. soja. Overexpression of GsNAC20 gene in the transgenetic lines of Arabidopsis thaliana resulted in enhanced sensitivity of the transgenic plants under salt stress. All results prove that GsNAC20 is a new member of the NAC family in G. soja, which is closely related to the stresses of salt and drought.

摘 要NAC (NAM, ATAF1/2, CUC2)转录因子作为一类新型转录因子已成为非生物胁迫基因工程领域的研究热点。本研究以野生大豆(Glycine soja)为材料, 利用酵母单杂交的方法筛选到一个能够与MYB1AT元件(核心序列为AAACCA)结合的转录因子基因, 该基因与大豆NAC20 (EU440353.1)基因具有99%的相似性, 命名为GsNAC20。GsNAC20蛋白含有典型的NAC结构域和转录激活区。酵母试验表明, GsNAC20转录因子能够与耐逆相关顺式元件MYB1AT特异结合, 但不具有自激活功能。细胞定位分析证明该基因位于细胞核中, 符合转录因子的特征。GsNAC20能够响应高盐、干旱和低温胁迫, 并且在根和叶中具有不同的表达模式。超量表达GsNAC20基因的拟南芥对盐胁迫的敏感性提高。以上结果表明GsNAC20参与植物非生物胁迫反应过程, 该基因在非生物胁迫基因工程研究领域具有良好的理论研究和实际应用价值。