Isolation and Characterization of a GS2 Gene in Melon (Cucumis melo L.) and its Expression Patterns under the Fertilization of Different Forms of N
Isolation and Characterization of a GS2 Gene in Melon (Cucumis melo L.) and its Expression Patterns under the Fertilization of Different Forms of N
复制标题
DOI：
10.1007/s12033-009-9203-7
复制
发表时间：
2010-01-01
影响因子：
2.6
通讯作者：
Huang, Dan-Feng
中科院分区：
文献类型：
--
作者：
Deng, Yang-Wu;Zhang, Yi-Dong;Huang, Dan-Feng
我们利用RACE技术从甜瓜中克隆了一个新的谷氨酰胺合成酶基因M-GS 2（登录号：AY 773090）。6.3.1.2 M-GS 2基因全长1807 bp，开放阅读框（ORF）为1296 bp，编码432个氨基酸。该蛋白含有植物GS 2蛋白中保守的结构域，与其他高等植物GS 2酶具有广泛的序列同源性。M-GS 2在叶片中特异性表达，并且M-GS 2中的叶绿体转运肽（cTP）的鉴定表明其定位于叶绿体。如实时定量PCR所示，肥料中不同形式的氮（N）对M-GS 2的转录调控不同。铵和硝酸盐喂养只显着调节M-GS 2转录叶饥饿（0.75 mM）或中等（3.75 mM）N水平显着增加M-GS 2转录1天，降低到一个恒定的低水平后，2-3天，而足够的N水平（7.5 mM）有轻微的影响，在整个3天相比，控制。然而，谷氨酸喂养，不仅显着调节M-GS 2转录在叶（最初下降，然后增加到高于对照组的水平），但也在根，在那里它是不断上调。本研究结果表明，M-GS 2是第一个在甜瓜中克隆和鉴定的GS基因，甜瓜通过差异表达M-GS 2来响应氮肥的变化。
We isolated a novel glutamine synthetase (GS, EC 6.3.1.2) gene M-GS2 (accession: AY773090) by the RACE approach from melon. The full-length cDNA of M-GS2 is 1807 bp and contains a 1296 bp open reading frame (ORF) encoding 432 amino acids. The deduced protein contains conserved structural domains among plant GS2 proteins and shares extensive sequence homology with GS2 enzymes from other higher plants. M-GS2 expresses with specificity in leaf, and identification of a chloroplast transit peptide (cTP) in M-GS2 suggests that it localizes to the chloroplast. As shown by real-time quantitative PCR, distinct forms of nitrogen (N) found in fertilizers transcriptionally regulated M-GS2 differently. Ammonium and nitrate feeding only significantly regulated M-GS2 transcripts in leaf; starving (0.75 mM) or moderate (3.75 mM) N levels dramatically increased M-GS2 transcripts for 1 day, decreasing to a constant low level after 2-3 days, while sufficient N level (7.5 mM) had a minor effect throughout 3 days compared to controls. Glutamate feeding, however, not only significantly regulated M-GS2 transcripts in leaf (decreased initially then increased to higher levels than controls), but also in root, where it was up-regulated continuously. Our results suggested that M-GS2 is the first GS gene cloned and characterized in melon and melon responds to the variations in N fertilization by differentially expressing M-GS2.