巴西橡胶树中2个NADP-苹果酸酶基因的克隆和表达特性分析

从橡胶树中克隆2个NADP-ME(苹果酸酶)基因的全长cDNA,分别命名为HbNADP-ME1和HbNADP-ME2。HbNADP-ME1和HbNADP-ME2 cDNA全长分别为2 428、2 139 bp,分别编码643、593个氨基酸组成的蛋白,二者的氨基酸序列一致性高达87.25%,且分别与蓖麻和杨树的一个NADP-ME序列具有较高的序列一致性。2个HbNADP-ME蛋白都含有典型的植物NADP-ME蛋白的保守结构域,均富含亮氨酸(Leu),同属于非分泌型稳定蛋白。2个HbNADP-ME基因在橡胶树不同组织中的表达存在明显差异,在根中的表达量最高,种子和花中的表达量次之;另外,HbNADP-ME1基因在胶乳中受机械伤害有下调表达趋势,HbNADP-ME2基因在胶乳中受割胶处理也表现出下调表达趋势,而低温胁迫则显著诱导2个基因在叶片和根中的表达。结果说明,HbNADP-ME基因可能参与橡胶树的抗逆应答及代谢调控(包括胶乳代谢调控)。此结果为深入揭示橡胶树中NADP-ME基因的功能奠定了基础。

Molecular Cloning and Expression Analysis of NADP-malic Enzyme Gene in Hevea brasiliensis

NADP-malic enzyme is a key enzyme in malic acid metabolism pathway and plays important roles in the regulation of cellular pH homeostasis and stress responses in plants. Here, the full-length cDNAs of two NADP-ME genes were first cloned in Hevea brasiliensis(para rubber tree), and respectively, named HbNADP-ME1 and HbNADP-ME2. The cDNAs of HbNADP-ME1 and HbNADP-ME2 contained 2 428 bp and 2 139 bp nucleotides, and encoded proteins of 643 and 593 amino acids, respectively. HbNADP-ME1 and HbNADP-ME2 shared amino acid identities of 87.25%, and were highly homologous to NADP-ME proteins from Ricinus communis and Populus trichocarpa, respectively. Both HbNADP-ME proteins contained conservative domains typical of plant NADP-MEs, rich in leucine and belonging to the category of non-secreted stable proteins. The HbNADP-ME genes showed distinct expression patterns in different tissues, with the highest expression in roots, and then in seeds and flowers. The expression of HbNADP-ME1 gene was down regulated by wounding, and the expression of HbNADP-ME2 gene was down regulated by tapping, whereas low temperature conspicuously induced the expression of both HbNADP-ME genes in leaves and roots. The results suggested that the HbNADP-ME genes may play roles in the regulation of multiple metabolisms(e.g. latex metabolism)and stress responses in Hevea tree. The results presented will help unravel the physiological roles of the NADP-ME genes in Hevea tree.