藜麦NRT2基因家族的鉴定及表达分析

Identification and Expression Analysis of NRT2 Gene Family of Chenopodium quinoa

硝态氮是植物吸收氮素的2种主要形式之一,硝酸盐转运蛋白2(NRT2)在土壤中硝酸盐缺乏时发挥主导作用。为探究藜麦NRT2基因家族的特征和表达模式,利用生物信息学方法,对藜麦NRT2基因进行全基因组鉴定,并分析了其编码蛋白、染色体定位、基因结构、系统进化、顺式作用元件、组织表达特异性以及不同氮素水平处理后基因的表达模式。结果表明,藜麦中有15个NRT2基因,分布在7条染色体上,每个成员分别含有1~9个内含子及2~10个外显子,蛋白亚细胞定位预测其均定位在质膜上,为疏水性蛋白。同时,系统进化分析显示,藜麦NRT2蛋白家族属于2个亚家族,与拟南芥的亲缘关系更近。顺式作用元件分析显示,藜麦NRT2家族成员启动子区存在大量与生长发育及逆境胁迫等相关的顺式作用元件。藜麦NRT2基因家族成员在不同组织器官中的表达存在差异,在根、茎、叶中表达量较高。在低氮条件下,藜麦NRT2.4、NRT2.7、NRT2.15表达上调;0,25%N处理后藜麦NRT2.7、NRT2.15的表达量急剧增加。研究结果可为后续藜麦NRT2s基因克隆和功能以及氮素胁迫分析提供参考依据。

Nitrate nitrogen is one of the two main form of nitrogen uptaken by plants.Nitrate transporter 2(NRT2)plays a leading role in nitrogen uptake under nitrate deficiency conditions.In order to explore characteristics and expression pattern of NRT2 gene in Chenopodium quinoa,in the present study,fifteen members of C.quinoa NRT2s were identified based on bioinformatics analysis,and their encoding protein,chromosome location,gene structure,systematic evolution,promoter elements,tissue expression specificity and expression profile under different nitrogen levels were analyzed.The results showed that 15 NRT2s of C.quinoa were distributed on 7 chromosomes,each member contained 1-9 introns and 2-10 exons,respectively.These C.quinoa NRT2 proteins were predicted to be located on plasma membrane and belong to hydrophobic proteins.The evolutionary analysis found that the NRT2 protein family of quinoa belonged to two subfamilies,and they showed closer relationship to Arabidopsis thaliana.The cis-acting element analysis exhibited that the promoter regions of NRT2 had elements related to growth and stress responses.NRT2s showed varied expression profile in different C.quinoa tissues where more CqNRT2 members were higher expressed in roots,stems and leaves than those in other organs.The expression of CqNRT2.4,CqNRT2.7 and CqNRT2.15 was up-regulated under low nitrogen conditions where the expression levels of CqNRT2.7 and CqNRT2.15 were up-regulated sharply with 0 and 25%nitrogen treatment.The study might provide a reference basis for subsequent cloning,functional and nitrogen stress analysis of CqNRT2s gene.