Hu Honghong, You Jun, Fang Yujie, Zhu Xiaoyi, Qi Zhuyun, Xiong Lizhong
National Center of Plant Gene Research Wuhan, National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
Plant Mol Biol. 2008 May;67(1-2):169-81. doi: 10.1007/s11103-008-9309-5. Epub 2008 Feb 14.
Plants respond to adverse environment by initiating a series of signaling processes including activation of transcription factors that can regulate expression of arrays of genes for stress response and adaptation. NAC (NAM, ATAF, and CUC) is a plant specific transcription factor family with diverse roles in development and stress regulation. In this report, a stress-responsive NAC gene (SNAC2) isolated from upland rice IRA109 (Oryza sativa L. ssp japonica) was characterized for its role in stress tolerance. SNAC2 was proven to have transactivation and DNA-binding activities in yeast and the SNAC2-GFP fusion protein was localized in the rice nuclei. Northern blot and SNAC2 promoter activity analyses suggest that SNAC2 gene was induced by drought, salinity, cold, wounding, and abscisic acid (ABA) treatment. The SNAC2 gene was over-expressed in japonica rice Zhonghua 11 to test the effect on improving stress tolerance. More than 50% of the transgenic plants remained vigorous when all WT plants died after severe cold stress (4-8 degrees C for 5 days). The transgenic plants had higher cell membrane stability than wild type during the cold stress. The transgenic rice had significantly higher germination and growth rate than WT under high salinity conditions. Over-expression of SNAC2 can also improve the tolerance to PEG treatment. In addition, the SNAC2-overexpressing plants showed significantly increased sensitivity to ABA. DNA chip profiling analysis of transgenic plants revealed many up-regulated genes related to stress response and adaptation such as peroxidase, ornithine aminotransferase, heavy metal-associated protein, sodium/hydrogen exchanger, heat shock protein, GDSL-like lipase, and phenylalanine ammonia lyase. Interestingly, none of the up-regulated genes in the SNAC2-overexpressing plants matched the genes up-regulated in the transgenic plants over-expressing other stress responsive NAC genes reported previously. These data suggest SNAC2 is a novel stress responsive NAC transcription factor that possesses potential utility in improving stress tolerance of rice.
植物通过启动一系列信号传导过程来应对不利环境，这些过程包括激活转录因子，而转录因子可调控一系列应激反应和适应相关基因的表达。NAC（NAM、ATAF和CUC）是植物特有的转录因子家族，在植物发育和胁迫调控中具有多种作用。在本报告中，对从旱稻IRA109（水稻粳稻亚种）中分离出的一个胁迫响应NAC基因（SNAC2）在胁迫耐受性方面的作用进行了表征。已证明SNAC2在酵母中具有反式激活和DNA结合活性，且SNAC2-GFP融合蛋白定位于水稻细胞核中。Northern杂交和SNAC2启动子活性分析表明，SNAC2基因受干旱、盐度、寒冷、创伤和脱落酸（ABA）处理诱导。将SNAC2基因在粳稻中花11中过表达，以测试其对提高胁迫耐受性的影响。在严重冷胁迫（4-8摄氏度，持续5天）后所有野生型植株死亡时，超过50%的转基因植株仍保持活力。在冷胁迫期间，转基因植株的细胞膜稳定性高于野生型。在高盐条件下，转基因水稻的发芽率和生长速率显著高于野生型植株。SNAC2的过表达还可提高对聚乙二醇处理的耐受性。此外，过表达SNAC2的植株对ABA的敏感性显著增加。对转基因植株的DNA芯片分析揭示了许多与应激反应和适应相关的上调基因，如过氧化物酶、鸟氨酸转氨酶、重金属相关蛋白、钠/氢交换体、热休克蛋白、GDSL样脂肪酶和苯丙氨酸解氨酶。有趣的是，过表达SNAC2的植株中上调的基因与先前报道的过表达其他胁迫响应NAC基因的转基因植株中上调的基因均不匹配。这些数据表明，SNAC2是一种新型的胁迫响应NAC转录因子，在提高水稻胁迫耐受性方面具有潜在应用价值。
