ACCUMULATION OF GLUTAMINE-SYNTHETASE DURING EARLY DEVELOPMENT OF MARITIME PINE (PINUS-PINASTER) SEEDLINGS
ACCUMULATION OF GLUTAMINE-SYNTHETASE DURING EARLY DEVELOPMENT OF MARITIME PINE (PINUS-PINASTER) SEEDLINGS
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DOI：
10.1007/bf00201059
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发表时间：
1991-01-01
期刊：
影响因子：
4.3
通讯作者：
DEVICENTE, A
中科院分区：
文献类型：
--
作者：
CANOVAS, FM;CANTON, FR;DEVICENTE, A
艾顿松 (Pinus pinaster Aiton) 幼苗在完全黑暗的环境下生长时会积累叶绿素 (Chl)。 叶绿素 a 和叶绿素 b 的含量在发芽过程中增加，在光照和黑暗生长的植物中达到相似的水平。 在胚胎中检测到谷氨酰胺合成酶（GS；EC 6.3.1.2）活性，并且其水平在深色发芽幼苗的子叶中显着增加。 当种子在白光存在下发芽时，观察到相似水平的 GS 活性。 通过离子交换色谱仅发现一种 GS 形式，其在约 0.1 M KCl 下洗脱。 在子叶中检测到了 43 kDa 的主要 GS 多肽，并且其稳态水平随着以不依赖于光的方式发育而增加。 在根和针叶中，43 kDa 的相关 GS 多肽是通过蛋白质印迹分析可检测到的独特种类。 分离叶绿体中可溶性蛋白的免疫印迹显示 GS 蛋白丰度较低，表明松子叶中谷氨酰胺的合成主要发生在细胞质中。 用分离的枝条进行的供氮实验表明，NO3- 和 NH4+ 都不能调节 GS 水平和多肽模式。 我们的结果表明，光和氮供应等环境因素对松树发育过程中 GS 积累的作用有限。
Seedlings of Pinus pinaster Aiton accumulated chlorophyll (Chl) when grown in complete darkness. Contents of Chl a and Chl b increased during germination, reaching similar levels in light- and dark-grown plants. Glutamine-synthetase (GS; EC 6.3.1.2) activity was detected in the embryo and its level increased markedly in cotyledons of dark-germinated seedlings. Similar levels of GS activity were observed when the seeds were germinated in the presence of white light. Only one GS form, which eluted at about 0.1 M KCl, was found by ion-exchange chromatography. A predominant GS polypeptide of 43 kDa was detected in cotyledons, and its steady-state level increased with development in a light-independent fashion. In roots and needles, a related GS polypeptide of 43 kDa was the unique species detectable by western blot analysis. Immunoblots of soluble proteins from isolated chloroplasts showed low abundance of GS protein, indicating that glutamine synthesis in pine cotyledons occurs mainly in the cytosol. Nitrogen-feeding experiments carried out with detached shoots indicated that neither NO3- nor NH4+ regulate GS levels and the polypeptide pattern. Our results indicate that environmental factors, such as light and nitrogen supply, have a limited role in GS accumulation during pine development.