| 摘要: |
| 【目的】克隆胡杨木葡聚糖内转糖苷酶/水解酶基因PeXTH，并研究该基因和植物抗Cd2+性之间的关系。【方法】利用RT-PCR方法从胡杨中克隆一个木葡聚糖内转糖苷酶/水解酶基因PeXTH，将该基因的全长cDNA克隆到植物表达载体pGreen0029上，然后通过农杆菌介导法，将重组表达载体转入烟草，并对转基因烟草的抗Cd2+能力进行初步分析。【结果】PeXTH基因的开放阅读框（ORF）长867 bp，含ATG起始密码子和TAG终止密码子，编码由288个氨基酸组成的蛋白；多重氨基酸序列比对结果显示，PeXTH蛋白含有木葡聚糖内转糖苷酶/水解酶（XTHs）的保守催化活性域DEIDFEFLG和N－糖基化位点NLSG；Real-Time PCR检测结果表明，PeXTH基因已经成功在2个转基因株系（L6和L14）中过表达；Cd2+胁迫后，转基因烟草根组织中积累的Cd2+含量显著高于野生型，而叶组织中积累的Cd2+含量明显低于野生型；Cd2+胁迫下，转基因烟草叶片的相对电导率显著低于野生型，但抗氧化酶活性、营养元素含量、叶片净光合速率和蒸腾速率等生理指标都要明显高于野生型。【结论】PeXTH基因的过表达提高了烟草对Cd2+的抗性，为进一步深入研究PeXTH基因在植物抗Cd2+机制中的作用奠定了良好基础。 |
| 关键词: 胡杨 烟草 PeXTH Cd2+ 抗Cd2+性 |
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| 基金项目:国家自然科学基金项目（31270654，31170570，31200470）；北京市自然科学基金项目（6112017）；北京市优秀博士学位论文指导教师专项基金项目（YB20081002201）；高等学校学科创新引智计划项目（B13007）；中央高校基本科研业务费专项（JC2011-2，TD-2012-04） |
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| Cloning of Populus euphratica PeXTH gene and its effect on Cd2+ tolerance of transgenic tobacco |
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HAN Yan-sha,LU Yan-jun,YU Rui,et al
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| Abstract: |
| 【Objective】The aim of this study was cloning a putative xyloglucan endotransglucosylase/ hydrolase gene (PeXTH) of Populus euphratica and analyzing its role in Cd2+ tolerance of transgenic tobacco plants.【Method】The PeXTH gene was isolated from Populus euphratica leaves by RT-PCR.The full-length cDNA of PeXTH was cloned into the expression vector pGreen0029,and then the recombinant pGreen0029 PeXTH was transferred into tobacco plants through Agrobacterium mediated method.Anti Cd2+ characters of the transgenic lines were analyzed.【Result】The PeXTH gene contained an open reading frame of 867 bp encoding a putative protein with 288 amino acids with the start codon of ATG and the termination codon of TAG.The putative amino acids sequence of PeXTH contained the conserved DEIDFEFLG domain and the N-glycosylation motif NLSG.Real-Time PCR analysis showed PeXTH gene was overexpressed in two transgenic tobacco lines.Compared to wild plants,transgenic tobacco had higher Cd2+ concentrations in roots and lower Cd2+ concentrations in leaves.Under Cd2+ stress,the relative electrolytic leakage in leaves of transgenic plants was significantly lower than that of wild plants,while antioxidant enzyme activities,nutrient element contents,net photosynthetic rates and transpiration rates in leaves of transgenic tobacco plants were significantly higher.【Conclusion】Overexpression of PeXTH enhanced Cd2+ tolerance of tobacco plants. |
| Key words: Populus euphratica tobacco PeXTH Cd2+ Cd2+ tolerance |
