Lu Tingting, Liu Lulu, Wei Minjing, Liu Yingying, Qu Zianshang, Yang Chuanping, Wei Hairong, Wei Zhigang
State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, Harbin, China.
School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI, United States.
Front Plant Sci. 2018 Jan 19;9:9. doi: 10.3389/fpls.2018.00009. eCollection 2018.
The glutamine synthetase (GS1) is a key enzyme that catalyzes the reaction of glutamate and ammonia to produce glutamine in the nitrogen (N) metabolism. Previous studies on in several plant species suggest that overexpression of GS1s can enhance N utilization, accelerate plant vegetative growth, and change wood formation. In this study, we isolated a gene, termed , from This gene was expressed at a higher level in roots, and relatively lower but detectable levels in xylem, leaves and phloem of . The protein encoded by is primarily located in the cytoplasm. Overexpression of in tobacco led to the increased GS1 activity and IAA content, the augmented N assimilation, and the enlarged leaves with altered anatomical structures. These changes presumably promoted photosynthetic, growth, and biomass productivity. It was noteworthy that the secondary cell walls and fiber characteristics changed remarkably in transgenic tobacco. These changes aligned well with the altered expression levels of the genes involved in fiber development, secondary cell wall component biosynthesis, IAA biosynthesis, amino acid transport, and starch breakdown. Taken together, the results from our study suggest that catalytic functions of on N assimilation and metabolism in transgenic tobacco had significant effects on vegetative growth, leaf development, and secondary cell wall formation and properties through acceleration of photosynthesis and IAA biosynthesis, and redirection of carbon flux to synthesis of more cellulose and hemicellulose.
谷氨酰胺合成酶（GS1）是一种关键酶，在氮（N）代谢中催化谷氨酸和氨反应生成谷氨酰胺。先前对几种植物物种的研究表明，GS1的过表达可以提高氮的利用率，加速植物营养生长，并改变木材形成。在本研究中，我们从[植物名称]中分离出一个名为[基因名称]的基因。该基因在根中表达水平较高，而在[植物名称]的木质部、叶片和韧皮部中表达水平相对较低但可检测到。[基因名称]编码的蛋白质主要位于细胞质中。在烟草中过表达[基因名称]导致GS1活性和吲哚乙酸（IAA）含量增加，氮同化增强，叶片增大且解剖结构改变。这些变化可能促进了光合作用、生长和生物量生产力。值得注意的是，在[基因名称]转基因烟草中，次生细胞壁和纤维特性发生了显著变化。这些变化与参与纤维发育、次生细胞壁成分生物合成、IAA生物合成、氨基酸运输和淀粉分解的基因表达水平改变密切相关。综上所述，我们的研究结果表明，[基因名称]在转基因烟草中对氮同化和代谢的催化功能通过加速光合作用和IAA生物合成以及将碳通量重新导向合成更多的纤维素和半纤维素，对营养生长、叶片发育以及次生细胞壁的形成和特性产生了显著影响。
