Group of Biotechnology of Pharmaceutical Plants, Laboratory of Pharmacognosy, Division of Pharmacognosy-Pharmacology, Department of Pharmaceutical Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece.
Plant Signal Behav. 2009 Nov;4(11):1099-101. doi: 10.4161/psb.4.11.9873. Epub 2009 Nov 18.
The arginine biosynthetic pathway represents an area of plant biochemistry that has been poorly investigated. Recently, the first enzyme of the arginine pathway, encoded by the N-acetyl-L-glutamate synthase gene (SlNAGS1), was isolated and characterized in tomato, and was found to be structurally similar to other predicted NAGS. SlNAGS1 accumulation patterns suggest a possible role of this gene in hypoxia-induced responses. The 35S::SlNAGS1 Arabidopsis plants accumulated ornithine at high levels and exhibited increased tolerance to salt and drought stresses. Ornithine is the intermediate compound in the arginine biosynthesis where the pathway divaricates to the production of compounds, such as proline and polyamines that are known to serve osmoprotective functions. It is therefore likely that the elevated ornithine accumulation in the SlNAGS1-overexpressing plants be coupled with the production of a pool of osmoprotectants that end up to the improved stress tolerance. The possible implications of ornithine accumulation are discussed.
精氨酸生物合成途径是植物生物化学中一个研究甚少的领域。最近，在番茄中分离并鉴定了精氨酸途径的第一个酶，即 N-乙酰-L-谷氨酸合酶基因（SlNAGS1），并发现其结构与其他预测的 NAGS 相似。SlNAGS1 的积累模式表明该基因可能在缺氧诱导的反应中发挥作用。35S::SlNAGS1 拟南芥植物积累大量的鸟氨酸，表现出对盐和干旱胁迫的更高耐受性。鸟氨酸是精氨酸生物合成中的中间化合物，该途径分支为产生脯氨酸和多胺等化合物，这些化合物已知具有渗透保护功能。因此，SlNAGS1 过表达植物中鸟氨酸的积累可能与产生一组渗透保护剂有关，这些渗透保护剂最终提高了对胁迫的耐受性。讨论了鸟氨酸积累的可能影响。
