巴西橡胶树磷酸蔗糖磷酸化酶基因的克隆和表达模式分析

Cloning and Expression of a Sucrose Phosphate Phosphatase Gene from Hevea brasiliensis

蔗糖是橡胶生物合成的主要碳源,而磷酸蔗糖磷酸化酶(SPP)是蔗糖合成最后步骤的关键酶,克隆橡胶树SPP家族基因并研究其表达特性,将有助于揭示橡胶树中蔗糖合成代谢的分子调控。本研究利用拟南芥和杨树的SPP氨基酸序列为探针,搜索橡胶树EST和基因组数据库,并设计引物进行PCR扩增,得到1个橡胶树SPP基因的cDNA和基因组序列,命名为HbSPP1。序列分析显示,HbSPP1基因组含有8个外显子、7个内含子,其cDNA序列的编码区(CDS)为1 278 bp,编码424个氨基酸,蛋白分子量为48.1 ku,等电点为6.02。进化上,HbSPP1基因与杨树SPP基因的亲源关系比拟南芥要近。组织特异性表达分析发现,HbSPP1在叶片中的表达丰度最高。另外,在叶片不同发育阶段中,HbSPP1在稳定期叶片中的表达明显低于幼期叶片。

Sucrose is the major carbon source used in rubber biosynthesis, and sucrose phosphate phosphatase （SPP）is the key enzyme catalyzing the last step of sucrose biosynthesis. Based on the Hevea brasiliensis EST and genome sequences with the SPP amino acid sequences of Populus and Arabidopsis, one Hevea SPP gene was cloned, named as HbSPP1. Sequence analysis revealed that the CDS length of HbSPP1 was 1 278 bp, encoding a protein of 424 amino acids with an average molecular weight of 48.1 ku, and a pI value of 6.02. Exon/intron structure analysis revealed 8 exons and 7 introns in HbSPP1 genomic sequence. Phylogenetically, HbSPP1 is more related to the orthologus of Populus than those of Arabidopsis. The tissue-specific expression analysis indicated that the HbSPP1 was mainly expressed in leaves. In addition, HbSPP1 expressions showed no obvious change in the three stages of immature leaves, but were markedly depressed in mature leaves. The results presented here would be conductive to further elucidating the functions of HbSPP1, and also the roles of SPP genes in the regulation of sucrose metabolism in H.brassiliensis.