烟草多酚氧化酶基因的克隆与序列分析

摘要

多酚氧化酶( PPO)在高等植物中广泛存在，其利用分子氧催化氧化酚类物质为醌，对植物的抗虫和抗病起着一定的作用，同时它介导的酶促反应也是烤制中烟草褐变的主要原因。本文采用RT－PCR，成功地从野生烟草( Nicotiana tabacum)叶片中克隆出了PPO cDNA序列。序列分析表明，烟草PPO基因ORF长为1773 bp，编码590个氨基酸，基因登陆号为KC540916，烟草与其他物种PPO的核苷酸序列与氨基酸序列同源性达80％以上，并包含两个高度保守的铜离子结合区域。烟草PPO基因的克隆为烟草的抗性研究和褐化反应的控制研究提供了良好的理论基础。%Polyphenol oxidases( PPO) , catalyzing the oxygen-dependent oxidation ofphenols to quinines,areubiquitous a﹣mong higher plantspecies, and assumedto beinvolved in plant defense against pests and pathogens. It had been proved to be the primary response for the deleterious browning of flue-cured tobacco. Nicotiana tabacum PPO gene had been suc﹣cessfully cloned by RT-PCR methodology. Sequence analysis indicated that the lengthof open reading frameof Nicotiana tabacum PPOgene was 1773bp, encoding 590 amino acids, which achieved the GenBankaccession numberNo.KC540916. Being blasted with NCBI Database, the PPO gene identities between Nicotiana tabacum and the relatives were higher than 80% both in nucleotide and amino sequences. Two copper-binding conserved domains were predicted. The cloning and sequence analysis of Nicotiana tabacum PPO gene could bring new clues for further explorations of tobacco plant-pest in﹣teractions and browning reaction.