He Xin-Jian, Mu Rui-Ling, Cao Wan-Hong, Zhang Zhi-Gang, Zhang Jin-Song, Chen Shou-Yi
National Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Plant J. 2005 Dec;44(6):903-16. doi: 10.1111/j.1365-313X.2005.02575.x.
An NAC-type transcription factor gene AtNAC2 was identified from Arabidopsis thaliana when expression patterns of the genes from a microarray analysis were examined. The AtNAC2 expression was induced by salt stress and this induction was reduced in magnitude in the transgenic Arabidopsis plants overexpressing tobacco ethylene receptor gene NTHK1. AtNAC2 is localized in the nucleus and has transcriptional activation activity. It can form a homodimer in yeast. AtNAC2 was highly expressed in roots and flowers, but less expressed in other organs examined. In addition to the salt induction, the AtNAC2 can also be induced by abscisic acid (ABA), ACC and NAA. The salt induction was enhanced in the ethylene overproducer mutant eto1-1, but suppressed in the ethylene-insensitive mutants etr1-1 and ein2-1, and in the auxin-insensitive mutant tir1-1when compared with that in wild-type plants. However, the salt induction of AtNAC2 was not significantly affected in the ABA-insensitive mutants abi2-1, abi3-1 and abi4-1. These results indicate that the salt response of AtNAC2 requires ethylene signaling and auxin signaling pathways but does not require ABI2, ABI3 and ABI4, intermediates of the ABA signaling pathway. Overexpression of AtNAC2 in transgenic Arabidopsis plants resulted in promotion of lateral root development. AtNAC2 also promoted or inhibited downstream gene expressions. These results indicate that AtNAC2 may be a transcription factor incorporating the environmental and endogenous stimuli into the process of plant lateral root development.
通过检测基因芯片分析中基因的表达模式，从拟南芥中鉴定出一个NAC类型的转录因子基因AtNAC2。AtNAC2的表达受盐胁迫诱导，而过表达烟草乙烯受体基因NTHK1的转基因拟南芥植株中，这种诱导作用的强度降低。AtNAC2定位于细胞核，具有转录激活活性，能在酵母中形成同源二聚体。AtNAC2在根和花中高表达，而在其他检测的器官中表达较少。除了盐诱导外，AtNAC2还可被脱落酸（ABA）、乙烯利（ACC）和萘乙酸（NAA）诱导。与野生型植株相比，乙烯过量产生突变体eto1-1中盐诱导作用增强，而乙烯不敏感突变体etr1-1和ein2-1以及生长素不敏感突变体tir1-1中盐诱导作用受到抑制。然而，AtNAC2的盐诱导在ABA不敏感突变体abi2-1、abi3-1和abi4-1中没有受到显著影响。这些结果表明，AtNAC2的盐响应需要乙烯信号传导和生长素信号传导途径，但不需要ABA信号传导途径的中间体ABI2、ABI3和ABI4。在转基因拟南芥植株中过表达AtNAC2导致侧根发育的促进。AtNAC2还促进或抑制下游基因的表达。这些结果表明，AtNAC2可能是一个将环境和内源刺激整合到植物侧根发育过程中的转录因子。
