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脱落酸(abscisic acid,ABA)对植物的生长发育具有独特的调控功能,并在植物适应逆境环境中发挥重要作用。9-顺式环氧类胡萝卜素双加氧酶(NCED)是高等植物中ABA生物合成途径的一个关键酶。根据GenBank中的植物NCED基因的同源序列设计简并引物,通过RT-PCR及RACE技术从枸杞叶片中克隆到1个编码NCED的基因,命名为LbNCED。其cDNA全长为2316 bp,含有1个1824 bp的开放阅读框,编码1个含607氨基酸残基,分子量为67.38 kDa、等电点(pI)为6.43的假定蛋白,其氨基酸序列与番茄(Lycopersicon esculentum)和马铃薯(Solanum tuberosum)的同源性达90%,在N-末端具有1个含15个氨基酸的叶绿体转运肽。Southern杂交结果表明,该基因在枸杞基因组中以低拷贝形式存在。盐处理和脱水处理的枸杞叶片中LbNCED基因的表达与内源ABA的积累同步变化。
Abscisic acid (ABA) has a unique regulatory function on plant growth and development, and plays an important role in plant adaptation to adverse environment. 9-cis-epoxy carotenoid dioxygenase (NCED) is a key enzyme in the ABA biosynthesis pathway in higher plants. According to the homologous sequences of plant NCED gene in GenBank, degenerate primers were designed. One gene encoding NCED was cloned from Lycium barbarum by RT-PCR and RACE technology and named as LbNCED. The full-length cDNA was 2316 bp in length and contained an open reading frame of 1824 bp encoding a hypothetical protein containing 607 amino acid residues with a molecular mass of 67.38 kDa and an isoelectric point (pI) of 6.43. The deduced amino acid sequence was identical to that of tomato Lycopersicon esculentum and potato (Solanum tuberosum) have 90% homology and one 15 amino acid chloroplast transit peptide at the N-terminus. Southern hybridization results show that the gene is present in the low copy form of the Chinese wolfberry genome. The expression of LbNCED gene in the leaves of medlar treated with salt and dehydration changed synchronously with the accumulation of endogenous ABA.