The symbiosis phenotype and expression patterns of five nodule-specific genes of Astragalus sinicus under ammonium and salt stress conditions
The symbiosis phenotype and expression patterns of five nodule-specific genes of Astragalus sinicus under ammonium and salt stress conditions
复制标题
DOI：
10.1007/s00299-007-0346-3
复制
发表时间：
2007-08-01
影响因子：
6.2
通讯作者：
Zhou, Jun-Chu
中科院分区：
文献类型：
--
作者：
Chen, Da-Song;Li, You-Guo;Zhou, Jun-Chu
在以前的工作中，我们通过抑制性消减杂交从中华黄芪中分离出14个根瘤特异或根瘤增强基因。在这项研究中，我们进一步确定了盐胁迫和铵胁迫下中华根瘤菌五个根瘤特异基因的表达模式。用实时荧光定量RT-PCR定量检测被测基因的转录水平。结果表明：(1)约80 mM的氯化钠和所有含(NH4)(2)SO4的胁迫处理显著抑制了接种植株的固氮能力。约40 mM的氯化钠表现出相对较弱的抑制作用。(2)与正常条件下的阳性对照相比，所有氨胁迫均显著降低了所有基因的表达。(3)在无外源氮素的盐胁迫下，AsIIA255和AsE246的转录水平在处理3d后显著升高。而AsG2411、AsIIC2512和AsB2510的表达被80 mM的氯化钠抑制，而40 mM的氯化钠对AsG2411、AsIIC2512和AsB2510的表达无明显影响。(4)外源氮盐胁迫显著抑制AsG2411、AsIIC2512、AsB2510和AsIIA255的表达。而AsE246在含1 mM(NH4)(2)SO4的80 mM氯化钠中的转录水平仍高于阳性对照。3个半胱氨酸簇蛋白(CCP)基因(AsG2411、AsIIC2512、AsIIA255)和1个脂转移蛋白(LTP)基因(AsE246)在各处理中的表达谱与根瘤固氮能力的相关性可能解释了它们在共生和固氮过程中可能的作用的分子机制。我们的结果还表明AsIIA255和AsE246可能在中华绒螯蟹对盐胁迫的反应中发挥作用，从而促进固氮过程。
In previous works, we isolated 14 nodule-specific or nodule-enhanced genes from Astragalus sinicus by suppressive subtractive hybridization. In this study, we have further identified the expression patterns of five nodule-specific genes of A. sinicus under salt and ammonium stress. Transcription levels of genes tested were quantified by quantitative fluorescence real-time RT-PCR. Results showed that: (1) About 80 mM NaCl and all stress treatments containing (NH4)(2)SO4 significantly inhibited nitrogen-fixing capacity of inoculated plants. About 40 mM NaCl showed relative lighter inhibition. (2) Compare with positive control at normal conditions, the expressions of all genes were significantly reduced by all ammonium stress. (3) Under salt stress without exogenous nitrogen, transcription levels of AsIIA255 and AsE246 were significantly increased after treatment for 3 days. But expressions of AsG2411, AsIIC2512, and AsB2510 were suppressed by 80 mM NaCl and not significantly affected by 40 mM NaCl. (4) Under salt stress with exogenous nitrogen, expressions of AsG2411, AsIIC2512, AsB2510, and AsIIA255 were significantly suppressed. While, the transcription level of AsE246 under 80 mM NaCl containing 1 mM (NH4)(2)SO4 was still higher than that of positive control. The correlation of the expression profiles of three cysteine cluster protein (CCP) genes (AsG2411, AsIIC2512, AsIIA255) and one lipid transfer protein (LTP) gene (AsE246) with the nitrogen-fixing capacities of nodules in each treatments may explain the molecular mechanisms of their supposed functions in symbiosis and nitrogen-fixing process. Our results also implied that AsIIA255 and AsE246 might play a role in the response of A. sinicus to salt stress to facilitate the nitrogen-fixation process.