烟草NRAMP家族全基因组鉴定及响应重金属胁迫的表达分析

Genome-wide Identification of NRAMP Family and Expression Analysis in Response to HeavyMetal Stress in Nicotiana tabacum L.

天然抗性相关巨噬蛋白(natural resistance associated macrophage protein,NRAMP)是一类负责金属离子吸收与内稳态平衡相关的蛋白质,对植物生长发育起着至关重要的作用。本研究基于基因组学从重要经济作物烟草中鉴定了NtNRAMP基因家族10个成员并对其理化性质进行了分析。系统进化树结果显示植物NRAMP蛋白可聚为2个亚家族;比较烟草NtNRAMP基因家族的保守基序和内含子-外显子分布发现2个亚家族之间成员在基因结构和蛋白结构水平存在显著差异;启动子区域顺式作用元件显示多个NtNRAMP家族成员受到植物激素和环境胁迫的调控。qPCR结果显示NtNRAMP家族基因在根、茎、叶、花等组织中具有不同的表达模式;Cd胁迫能够导致所有烟草NtNRAMP家族基因表达水平显著上调;在营养缺陷处理中NtNRAMP1/2/3/6基因的表达水平显著受到Fe缺乏诱导而上调,暗示其与Fe的吸收与转运功能相关;此外,Zn缺乏胁迫显著诱导NtNRAMP1的表达,推测其与Zn的内稳态平衡相关。本研究鉴定烟草NtNRAMP基因家族成员并分析了其表达模式,为深入研究烟草NtNRAMP蛋白在金属离子吸收、转运和维持内稳态等生理进程发挥的生物学功能提供了参考信息。

Natural resistance-associated macrophage protein(NRAMP)is a class of proteins responsible for the absorption of metal ions and homeostasis,and plays a vital role in plant growth and development.Based on genomics,this study identified 10 members of the NtNRAMP gene family from tobacco,an important cash crop,and analyzed their physical and chemical properties.Phylogenetic tree results showed that plant NRAMP proteins were divided into two subfamilies.According to the results of the conserved motifs analysis and intron-exon structure of the tobacco NtNRAMP gene family,it is found that the members of the two subfamilies have significant differences in genomic and protein level;cis-acting elements in the promoter region showed that multiple NtNRAMP family members were regulated by plant hormones and environmental stress.The results of qPCR indicated that the NtNRAMP gene family showed different expression patterns in the five tissues including roots,stems,old leaves,young leaves and flowers;Cd stress could provoke the expression levels of all tobacco NtNRAMP family genes significantly;the expression level of NtNRAMP1/2/3/6 genes was significantly up-regulated by Fe deficiency,which suggested that most of NtNRAMP genes were related to the absorption and transport of Fe.In addition,Zn deficiency stress significantly induced the expression of NtNRAMP1,which was speculated to be related to the homeostasis of Zn.This study identified members of the NtNRAMP gene family in tobacco and analyzed their expression patterns,which provides references for the in-depth study of the biological functions of NtNRAMP proteins in the physiological processes of metal ion absorption,transport and homeostasis.