茶树CsAMT1s亚家族基因的克隆与表达

Molecular cloning and expression analysis of CsAMT1s gene subfamily in Camellia sinensis

铵转运蛋白AMT具有介导植物NH_(4)^(+)跨膜转运的功能,由于茶树会优先吸收铵态氮营养,因此AMT在其体内的调节功能是后续氨基酸等物质合成的有力保障.基于茶树基因组数据确定了5个茶树CsAMT1s亚家族成员,并从福鼎大白茶中成功克隆,参考拟南芥AtAMT1s的命名规律,将它们分别命名为CsAMT1.1-1.5.生物信息学分析显示,CsAMT1s蛋白具有7-11个跨膜区域,均含有具有铵转运特性的Ammonium;ransp结构域,且上游序列中含有大量与环境因子、生长发育相关的顺式作用元件.CsAMT1s在茶树各组织间的表达模式分析结果表明,CsAMT1.1与CsAMT1.4在花蕾与新梢部位中具有较高的表达量,其功能与营养器官与生殖器官发育过程中的NH_(4)^(+)供应有关,而CsAMT1.3与CsAMT1.5在各组织部位间的表达量相对平均,因此推测它们可能在NH_(4)^(+)从地下至地上部的运输过程中发挥着主要作用.进一步研究发现,在氮高效茶树品种福鼎大白茶的嫩茎与花蕾中,CsAMT1.4与CsAMT1.1的表达量明显高于龙井43,CsAMT1.1与CsAMT1.5在这两个品种根系中的表达量也具有差异,推测CsAMT1s在不同茶树品种间的转录水平不同,在一定程度上反映出它们对氮素吸收利用效率的差异.

The AMT proteins mediate NH_(4)^(+)transport across the membrane in plants.As tea plants(Camellia sinensis)would preferentially absorb nitrogen nutrition in the form of ammonium,the regulation of AMT proteins in tea plants should guarantee the biosynthesis of many substances,especially amino acids.In this study,five sequences of CsAMT1s gene subfamily were identi?ed based on tea plant genome,successfully cloned from the tea cultivar Fudingdabaicha,and named CsAMT1.1-1.5 respectively with reference to the naming rules of AtAMT1s.Further bioinformatics analysis showed that these CsAMT1 proteins contain 7-11 transmembrane structures,all of which harbored Ammonium_transp domains with ammonium transport properties,and their upstream sequences contained a large number of cis-acting elements involved in response to environmental factors,growth,and development.The analysis of tissue expression speci?city of CsAMT1s genes demonstrated that CsAMT1.1 and CsAMT1.4 had higher expression levels in?ower buds and new shoots,and their functions may be related to the supply of NH_(4)^(+)during the development of vegetative and reproductive organs,whereas the expression levels of CsAMT1.3 and CsAMT1.5 in each tissue were relatively unchanged.Therefore,we speculated that they might play a critical role in root-to-shoot translocation of NH_(4)^(+).Further research found that in tender stems and?ower buds of high nitrogen e?cient cultivar Fudingdabaicha,the expression levels of CsAMT1.4 and CsAMT1.1 were signi?cantly higher than those of Longjing 43.The expression levels of CsAMT1.1 and CsAMT1.5 in the roots of these two cultivars were also different.From these?ndings,we concluded that the transcription level diversities of CsAMT1s in different cultivars re?ected their discrepancy of nitrogen absorption and utilization effciency to some extent.