The differing responses of two Arabidopsis ecotypes to ammonium are modulated by the photoperiod regime
The differing responses of two Arabidopsis ecotypes to ammonium are modulated by the photoperiod regime
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DOI：
10.1007/s11738-010-0551-5
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发表时间：
2011-03-01
影响因子：
2.6
通讯作者：
Su, Yanhua
中科院分区：
文献类型：
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作者：
Li, Baohai;Shi, Weiming;Su, Yanhua
在水培条件下，比较了两种拟南芥生态型（Col-0和JA22）在不同光周期下对过量铵态氮（NH4（+））的反应。在本研究中，我们发现外源NH_4（+）对两种生态型拟南芥幼苗的生长有严重的抑制作用，并导致游离NH_4（+）和氨基酸的积累，以及谷氨酰胺合成酶（GS）和谷氨酸脱氢酶（GDH）活性的增加。与光（16 h）-暗（8 h）周期光周期相比，连续光照下，游离NH4（+）和总氨基酸含量增加，GS、NADH依赖的谷氨酸合成酶和GDH活性降低。统计分析表明，在高NH4（+）胁迫下，无论光周期如何，地上部的生长下降、游离NH4（+）积累、氨基酸总量和GS活性水平之间均存在着强相关性。有趣的是，在连续光照下，与JA22相比，Col-0表现出更强的抗生长抑制能力，并保持约1倍的将过量游离NH4（+）转化为氨基酸的能力，以及1倍的由外部NH4（+）诱导的GS活性。相反，在光暗循环条件下，Col-0和JA22之间的这些差异被消除。综上所述，Col-0和JA22对NH_4~（+）的敏感性在连续光照和光暗循环光周期之间发生了变化，这与地上部GS活性的变化有关。
Responses to excessive ammonium (NH4 (+)) were compared between two Arabidopsis ecotypes (Col-0, JA22) with respect to different photoperiods in hydroponics. In this study, we showed that external extra NH4 (+) led to severe growth suppression, accumulations of free NH4 (+) and amino acids and increased the activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) in shoots of the two Arabidopsis ecotypes. However, the levels of free NH4 (+) and total amino acids increased, whereas the activities of GS, NADH-dependent glutamate synthase and GDH decreased under the continuous light when compared with the light (16 h)-dark (8 h) cycle photoperiod. Statistical analyses suggested that strong correlations exist among the growth reduction, accumulations of free NH4 (+), total amino acids and levels of GS activity in shoots under the high NH4 (+) stress regardless of the photoperiod regimes. Interestingly, under the continuous light, Col-0 showed more resistant to such growth reduction and maintained about onefold higher capability of converting excess free NH4 (+) into amino acids, with onefold higher GS activity induced by the external NH4 (+) when compared with JA22. In contrast, these differences were abolished between Col-0 and JA22 under the light-dark cycle condition. Taken together, our results conclude that the sensitivity to NH4 (+) of Col-0 and JA22 is changed between the continuous light and the light-dark cycle photoperiod, which is correlative to the alteration of the GS activity in shoots.