毛白杨蔗糖合酶基因PtSUS1的克隆及其表达模式分析

Cloning and Expression Patterns of PtSUS1 in Populus tomentosa

蔗糖合酶（sucrose synthase）与植物库强调节、次生壁的形成和纤维素合成等有着密切的联系,其中在纤维素合成过程中的作用尤为显著。本研究根据我们已获得的毛白杨PtSUS1基因片段设计引物,采用RACE技术,获得了毛白杨PtSUS1的基因序列,测序结果显示该基因序列全长为2 669 bp,包括一个完整的阅读框,编码805个氨基酸。通过Blast检索分析表明,PtSUS1与拟南芥、巨桉、陆地棉、温州蜜柑、毛果杨SUS1的核酸和氨基酸序列的同源性分别达到76%~97%和82%~97%。运用生物信息软件对PtSUS1编码的蛋白进行了二级结构预测和功能位点分析,结果显示该蛋白氨基酸序列包括两个功能域,存在可能的磷酸化位点38个,无跨膜结构域存在。系统进化分析表明PtSUS1与PtSUS2关系最为接近。RT-PCR分析结果显示,PtSUS1在被检测的毛白杨根、茎、叶及雌雄花芽组织和器官中均有表达,呈现组成型表达模式。该研究为进一步深入探索毛白杨蔗糖合酶基因PtSUS1的功能奠定了基础。

ucrose synthase（SUS） was closely associated with sink strength,secondary wall formation and cellulose synthesis in plant.Among these items,cellulose synthesis is considered to be the most important.According to the known gene fragment of PtSUS1 and the principle of RACE amplification,we got the gene sequence of PtSUS1 from Populous tomentosa.The full sequence of PtSUS1 which contains an open reading frame（ORF） is 2 669 bp encoding a deduced amino acid sequence of 805 residues.Blast analysis results indicated that the homology was as high as 76% to 97% and 81% to 97%,respectively,when compared PtSUS1 sequence of amino acid and nucleotide with the ones of Arabidopsis thaliana,Eucalyptus grandis,Gossypium hirsutum,Citrus unshiu,and Populus trichocarpa.Furthermore,secondary structure and functional sites in amino acid sequences have been predicted by the bioinformatics technology,the results suggested that the encoded protein contains 2 functional domains,38 PKA phosphorylation sites and no transmembrane regions.Phylogenetic analysis demonstrated that PtSUS1 is most similar to PtSUS2.And the expression of PtSUS1 mRNA was detected in all the tissues and organs tested such as root,stem,leaves and flowers of Populus tomentosa by RT-PCR,presenting the constitutive expression pattern.The data of this paper will provide the basis for further gene function research of PtSUS1 in Populus tomentosa.