异源表达蒙古沙冬青AmDREB1F基因提高转基因拟南芥的耐逆性

Ectopic expression of the AmDREB1F gene from Ammopiptanthus mongolicus enhances stress tolerance of transgenic Arabidopsis

摘要:

脱水应答元件结合蛋白 (Dehydration-responsive element binding proteins，DREBs) 是一类重要的植物耐逆相关转录因子。蒙古沙冬青Ammopiptanthus mongolicus是中国西北荒漠区特有的强耐逆常绿阔叶灌木。为探明其AmDREB1F基因在耐受非生物逆境中的功能和作用机理，文中对该基因编码蛋白的亚细胞定位、表达模式和转基因拟南芥的耐逆性进行了分析。结果表明：AmDREB1F编码的蛋白质定位于细胞核内；在室内培养幼苗中，该基因在正常条件下不表达，在低温和干旱胁迫下有较明显表达，在高盐和高温胁迫下仅有微弱表达，而在脱落酸 (Abscisic acid，ABA) 处理下不表达；在野外生长植株的叶片中，其表达量在秋末、冬季和早春远高于其他季节，而不同器官相比，其在根和未成熟果荚中的表达量远高于其他器官；将AmDREB1F在拟南芥中组成型表达可提高多个受DREBs调控的胁迫响应基因的转录水平，增强转基因株系对干旱、高盐和低温以及氧化胁迫的耐性，同时导致其生长发育延滞，外施赤霉素3可消除生长延滞现象；将该基因进行胁迫诱导表达也可提高转基因拟南芥对上述非生物胁迫的耐受性，而不影响其生长发育。这些结果说明AmDREB1F可能通过ABA非依赖的信号途径在响应和耐受逆境胁迫中起正调节作用。

Abstract:

Dehydration-responsive element binding proteins (DREBs) are an important class of transcription factors related to plant stress tolerance. Ammopiptanthus mongolicus is an evergreen broadleaf shrub endemic to desert areas of northwest China, and it has a very high tolerance to harsh environments. In order to reveal the functions and mechanisms of the AmDREB1F gene from this species in enduring abiotic stresses, we performed subcellular localization test, expression pattern analysis, and stress tolerance evaluation of transgenic Arabidopsis harboring this gene. The protein encoded by AmDREB1F was localized in the nucleus. In laboratory-cultured A. mongolicus seedlings, the expression of AmDREB1F was induced significantly by cold and drought but very slightly by salt and heat stresses, and undetectable upon ABA treatment. In leaves of naturally growing shrubs in the wild, the expression levels of the AmDREB1F gene were much higher during the late autumn, winter and early spring than in other seasons. Moreover, the expression was abundant in roots and immature pods rather than other organs of the shrubs. Constitutive expression of AmDREB1F in Arabidopsis induced the expression of several DREB-regulated stress-responsive genes and improved the tolerance of transgenic lines to drought, high salinity and low temperature as well as oxidative stress. The constitutive expression also caused growth retardation of the transgenics, which could be eliminated by the application of gibberellin 3. Stress-inducible expression of AmDREB1F also enhanced the tolerance of transgenic Arabidopsis to all of the four stresses mentioned above, without affecting its growth and development. These results suggest that AmDREB1F gene may play positive regulatory roles in response to abiotic stresses through the ABA-independent signaling pathways.