Abstract:

Proline is one of the most important and widespread osmolyte which functions in adaptation to adverse environmental stresses in many organisms. Also it is an important carbon and nitrogen resource in higher plants. Metabolism of proline has been elucidated in many plant species. However, transport of proline was poorly characterized although transport system plays an important role in proline distribution in different tissues. We isolated one full length cDNA encoding proline transporter from the typical halophyte: Atriplex hortensis L. through cDNA library screening and 5′-RACE. The deduced amino acid sequence had eleven transmembrane domains, showed 60%-69% similarities to other ProTs and the gene was designated AhProT1 . In the phylogenetic tree, higher plants’ ProTs, e.g. AhProT1 , showed more similar to ProP from microorganisms than ProT from mammalians. AhProT1 gene was transformed into Arabidopsis thaliana under 35S promoter. In MS medium containing ［U-14C］ proline, AhProT1+ plants were able to accumulate much more radiolabeled proline in the roots than control plants. In MS medium containing different concentrations of NaCl, AhProT1+ plants could endure 200 mmol/L NaCl and keep development and biomass increase with proline supply, whereas control plants died back at 150 mmol/L NaCl.

榆钱菠菜脯氨酸转运蛋白基因的克隆及转基因拟南芥的耐盐性
沈义国₁*张万科_1*阎冬青₂ 杜保兴₁ 张劲松₁ 陈受宜_1**

（1.中国科学院遗传与发育生物学研究所，北京100101；2. 西北农林科技大学生命科学学院，陕西杨凌712100）

摘要： 脯氨酸是自然界中分布最广泛 ,作用最重要的渗透保护剂之一 ,同时又是高等植物中一类重要的碳源和氮源物质。为了解环境胁迫下脯氨酸的转运调节 ,从一个典型的盐生植物榆钱菠菜 (AtriplexhortensisL .)中通过cDNA文库筛选和 5′-RACE的方法获得了一个全长的cDNA (AhProT1) ,其编码蛋白与脯氨酸转运蛋白有 6 0 %～ 6 9%的同源性 ,含有 11个跨膜结构域。聚类分析表明 ,微生物和高等植物的脯氨酸转运蛋白同源程度相对高于哺乳动物。为进一步分析脯氨酸转运蛋白在植物中的功能 ,将AhProT1置于 35S启动子下转入拟南芥 (Arabidopsisthaliana)。通过同位素示踪法发现 ,与对照植物相比 ,转基因植物在根中积累更多的脯氨酸 ;在一系列不同浓度的盐胁迫试验中 ,转基因植株最高可耐受 2 0 0mmol/LNaCl,并可持续生长 ,而对照植株在 15 0mmol/LNaCl下即已死亡。

关键词： 榆钱菠菜；脯氨酸转运蛋白；沉积作用；盐胁迫

通讯作者。E-mail: sychen @ gemetocs.ac.cn; Fax:010-64873428 Tel.: 010-64886859

Key words: Atriplex hortensis, proline transporter, deposition, salt stress