Reverse genetics approach to characterize a function of NADH-glutamate synthase1 in rice plants
Reverse genetics approach to characterize a function of NADH-glutamate synthase1 in rice plants
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DOI：
10.1007/s00726-010-0531-5
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发表时间：
2010-10-01
期刊：
影响因子：
3.5
通讯作者：
Yamaya, Tomoyuki
中科院分区：
文献类型：
--
作者：
Tamura, Wataru;Hidaka, Yusuke;Yamaya, Tomoyuki
生长在厌氧水稻土上的水稻植株更喜欢使用铵离子作为无机氮源。氨离子通过谷氨酰胺合成酶(GS)和谷氨酸合成酶(GOGAT)的偶联反应被同化。在水稻中，有一个小的GOGAT基因家族：有两种依赖NADH的类型和一种依赖铁氧还蛋白(FD)的类型。FD-GOGAT在叶绿体中光呼吸产生的氨离子的再同化过程中起着重要作用。虽然两个NADH-GOGAT基因的细胞类型和年龄依赖性的表达已经被很好地描述，但单个基因产物的代谢功能还不完全清楚。反向遗传学方法是研究同工酶功能的直接方法。我们已经分离到一个缺失NADH依赖的谷氨酸合成酶1(NADH-GOGAT1)的水稻基因敲除突变体，我们的研究表明，该同工酶对苗期根系的初级铵同化起重要作用。NADH-GOGAT1在水稻生长至收获时对有效分蘖数的发育也具有重要作用。NADH-GOGAT2和Fd-GOGAT在突变体中的表达与野生型相同，表明这些GOGATs不能补偿NADH-GOGAT1的功能。
Rice plants grown in anaerobic paddy soil prefer to use ammonium ion as an inorganic nitrogen source for their growth. The ammonium ions are assimilated by the coupled reaction of glutamine synthetase (GS) and glutamate synthase (GOGAT). In rice, there is a small gene family for GOGAT: there are two NADH-dependent types and one ferredoxin (Fd)-dependent type. Fd-GOGAT is important in the re-assimilation of photorespiratorily generated ammonium ions in chloroplasts. Although cell-type and age-dependent expression of two NADH-GOGAT genes has been well characterized, metabolic function of individual gene product is not fully understood. Reverse genetics approach is a direct way to characterize functions of isoenzymes. We have isolated a knockout rice mutant lacking NADH-dependent glutamate synthase1 (NADH-GOGAT1) and our studies show that this isoenzyme is important for primary ammonium assimilation in roots at the seedling stage. NADH-GOGAT1 is also important in the development of active tiller number, when the mutant was grown in paddy field until the harvest. Expression of NADH-GOGAT2 and Fd-GOGAT in the mutant was identical with that in wild-type, suggesting that these GOGATs are not able to compensate for NADH-GOGAT1 function.