Zhong Li, Chen Dandan, Min Donghong, Li Weiwei, Xu Zhaoshi, Zhou Yongbin, Li Liancheng, Chen Ming, Ma Youzhi
National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Guizhou Institute of Prataculture, Guizhou Academy of Agricultural Sciences, Guiyang, Guizhou 550006, China.
College of Life Sciences, Northwest A&F University, Yangling, Shanxi 712100, China.
Biochem Biophys Res Commun. 2015 Feb 13;457(3):433-9. doi: 10.1016/j.bbrc.2015.01.009. Epub 2015 Jan 13.
To cope with environmental stress caused by global climate change and excessive nitrogen application, it is important to improve water and nitrogen use efficiencies in crop plants. It has been reported that higher nitrogen uptake could alleviate the damaging impact of drought stress. However, there is scant evidence to explain how nitrogen uptake affects drought resistance. In this study we observed that bZIP transcription factor AtTGA4 (TGACG motif-binding factor 4) was induced by both drought and low nitrogen stresses, and that overexpression of AtTGA4 simultaneously improved drought resistance and reduced nitrogen starvation in Arabidopsis. Following drought stress there were higher nitrogen and proline contents in transgenic AtTGA4 plants than in wild type controls, and activity of the key enzyme nitrite reductase (NIR) involved in nitrate assimilation processes was also higher. Expressions of the high-affinity nitrate transporter genes NRT2.1 and NRT2.2 and nitrate reductase genes NIA1 and NIA2 in transgenic plants were all higher than in wild type indicating that higher levels of nitrate transport and assimilation activity contributed to enhanced drought resistance of AtTGA4 transgenic plants. Thus genetic transformation with AtTGA4 may provide a new approach to simultaneously improve crop tolerance to drought and low nitrogen stresses.
为应对全球气候变化和过量施氮所造成的环境压力，提高作物的水分和氮素利用效率至关重要。据报道，较高的氮素吸收量可以减轻干旱胁迫的破坏性影响。然而，几乎没有证据能解释氮素吸收如何影响抗旱性。在本研究中，我们观察到bZIP转录因子AtTGA4（TGACG基序结合因子4）受干旱和低氮胁迫诱导，并且AtTGA4的过表达同时提高了拟南芥的抗旱性并减轻了氮饥饿。干旱胁迫后，转基因AtTGA4植株中的氮和脯氨酸含量高于野生型对照，参与硝酸盐同化过程的关键酶亚硝酸还原酶（NIR）的活性也更高。转基因植株中高亲和力硝酸盐转运蛋白基因NRT2.1和NRT2.2以及硝酸还原酶基因NIA1和NIA2的表达均高于野生型，表明较高水平的硝酸盐转运和同化活性有助于增强AtTGA4转基因植株的抗旱性。因此，用AtTGA4进行遗传转化可能为同时提高作物对干旱和低氮胁迫的耐受性提供一种新方法。
