蔷薇科果树TMT基因家族生物信息学分析

[目的]本文旨在对蔷薇科果树液泡膜单糖转运蛋白（TMT）基因家族成员进行鉴定，分析其染色体定位、序列特性、进化关系及在白梨中的表达特征，为蔷薇科果树TMT基因功能研究和利用奠定基础。[方法]基于苹果、草莓、梅、桃、白梨、西洋梨和黑树莓7个蔷薇科果树物种的全基因组测序结果，应用生物信息学方法进行序列分析，通过RT-qPCR技术分析白梨TMT基因在各器官组织中和果实不同发育阶段的表达特性。[结果]苹果、草莓、梅、桃、白梨、西洋梨和黑树莓等TMT基因家族成员数量分别为5、2、4、4、6、4、2，各物种TMT基因不均匀地分布在2~4条染色体上。TMT蛋白结构高度保守，均存在11个α螺旋跨膜结构域，氨基酸序列长度700左右，等电点（pI）为4.79~5.93，最大疏水系数为0.312~0.438，为疏水性蛋白，亚细胞定位预测均位于液泡膜。系统进化分析表明，7个蔷薇科果树物种的TMT家族基因明显聚为两组，组Ⅰ中的TMT基因可能为其主要的功能基因。TMT基因家族经历过2次全基因组复制事件，进化过程中主要受纯化选择作用。定量分析发现，白梨中鉴定的PbTMT1、PbTMT2、PbTMT3在成熟叶中和果实膨大期表达量最高，PbTMT4的表达量随着果实发育不断增高，PbTMT6的表达量在成熟叶中最高，而在果实发育后期急剧下降。[结论]蔷薇科果树TMT基因家族成员高度保守，主要在液泡膜上起重要功能，不仅在果实糖分积累过程中发挥重要作用，还参与了植物发育和抗逆过程。
[Objectives]In order to study the functional characterization of tonoplast monosaccharide transporter(TMT)genes in the future,TMT genes were identified in fruit trees of Rosaceae and their structural feature,phylogenetic tree,and expression characteristics in Pyrus bretschneideri were explored. [Methods]Based on the sequenced results of whole genome from Malus domestica,Fragaria×vesca,Prunus mume,Prunus persica,Pyrus bretschneideri,Pyrus communis and Rubus occidentalis,the sequences were analyzed by the method of bioinformation,and the expression characteristic of TMT genes in P. bretschneideri was analysed by RT-qPCR. [Results]The TMT genes number of M. domestica,F. vesca,P. mume,P. persica,P. bretschneideri,P. communis and R. occidentalis was 5,2,4,4,6,4,2,respectively. All of the TMT genes were highly conservative,and the amino acid sequences of all TMT genes were about 700,which contained 11 putative transmembrane α-helices,the theoretical isoelectric point(pI)from 4.79 to 5.93,the grand average of hydropathicity between 0.312 and 0.438,and the protein sequences were located in the vacuole membrane based on the subcellular localization prediction. Phylogenetic tree analysis showed that TMT genes could be classified into two groups. GroupⅠcontained main functional genes of TMT genes family. Evolutionary analysis showed that there were two whole genome duplication events of TMT gene family during the evolution process,and the selective pressure was main factors. The expression analysis in P. bretschneideri showed that the PbTMT1,PbTMT2 and PbTMT3 had higher expression in mature leaves,the expression of PbTMT4 increased with the development of fruit,and PbTMT6 had higher expression in mature leaf but declined sharply during the late stage of fruit development. [Conclusions]TMT gene family in fruit trees of Rosaceae contained a highly conserved domain,and the TMT genes localized in the vacuole membrane not only involved in