转betA基因的小黑杨花粉植株耐盐性分析

The Analysis of Salt Tolerance of Transgenic Poplus simonii×P. nigra Pollen plantlets with betA Gene

甘氨酸甜菜碱是植物细胞内一种重要的调渗物质,盐胁迫下,甘氨酸甜菜碱的积累可以保护细胞内蛋白质的结构和功能,降低细胞水势,从而增强植物自身的耐盐能力。从大肠杆菌中克隆的胆碱脱氢酶基因(betA)是甘氨酸甜菜碱合成的关键酶基因,该基因编码的胆碱脱氢酶(CDH)可将胆碱一步合成为甜菜碱。本实验室已将胆碱脱氢酶基因(betA)转入到小黑杨花粉植株基因组中,并最终获得了4个转基因株系。本研究以4个转betA基因株系(TB1、TB2、TB3、TB4)及非转基因对照为试材,在浓度为1.2%的NaCl盐胁迫下,测定其甜菜碱含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性和丙二醛(MDA)含量,并调查试材的盐害情况,计算盐害指数,目的是为了研究转基因株系的耐盐效果,从中筛选出耐盐能力较强的转基因株系。试验结果表明,4个转基因株系的甜菜碱含量均高于非转基因对照;在1.2%NaCl胁迫下TB1、TB2、TB4的超氧化物歧化酶活性、过氧化物酶活性均高于非转基因对照,TB3低于对照;TB1、TB4的丙二醛含量低于对照,TB2、TB3与对照相近。进一步的盐害分析表明4个转基因株系中的TB1和TB4株系的盐害指数低于对照的42.1%和33.4%,TB2、TB3与对照无显著差异。综合各转基因株系的耐盐性及生理指标测定结果,4个转基因株系中,TB1、TB2的耐盐性明显优于对照,有希望用于盐碱地造林及推广。

Betaine is an important osmolyte in plant cells. Under salt stress conditions, it can protect structures and functions of proteins, decreases cellular water potential, and results in improved salt stress tolerance of plants. Choline dehydrogenase （CDH） is a key enzyme in betaine synthesis. It can synthesize betaine from choline in one step. In our study, choline dehydrogenase gene （betA） cloned from E.coli was transformed into Populus simonii×P, nigra and four transgenic plants were obtained. BetA transgenic lines （TB1,TB2,TB3,TB4） and control plants were used for salt tolerance tests. In exposure to 1.2% NaCl, betaine content, superoxide dismutase（SOD） activity, peroxidase （POD） activity and MDA content were measured, salt damage was investigated, and salt-harm index was calculated. The results indicated that betaine content of the 4 transgenic lines were all higher than control plants under salt stress condition; superoxide dismutase activity and peroxidase activity of TB1, TB2 and TB4 were higher than control plants, but TB3 was lower than control plants; MDA content of TB1 and TB4 was lower than control plants, TB2 and TB3 appeared to be similar with control plants. The analysis of salt damage showed that the salt-harm index of TB1 and TB4 was 42.1% and 33.4% lower than control plants respectively, but there was not remarkable difference among TB2 TB3 and control plants. Based on the salt tolerance and physiological index under salt stress conditions, the transgenic lines, TB1 and TB2 are more suitable for forestation in salt-alkaline area than the other transgenic lines and control plants.