5种蔷薇科树种多酚氧化酶比较基因组学分析

Comparative Genomics Analysis of the Polyphenol Oxidase Genes Among Five Rosaceae Species

蔷薇科植物中有多种具有重要价值的水果,如苹果、梨、桃、草莓和黑树莓等。这些水果普遍容易发生由多酚氧化酶(PPO)介导的酶促褐变而导致重大经济损失,从全基因组角度分析比较PPO基因家族,有助于加深对PPO基因家族和功能的认识。采用比较基因组学的方法,对这5种植物的PPO基因家族进行了基因鉴定、染色体定位、编码蛋白的亚细胞定位、内含子统计分析、基因系统进化、基因倍增与丢失等特征分析。从这5种植物中,共计鉴定出了42个PPO基因,其中6个基因被认定是假基因;绝大多数基因编码的蛋白定位于叶绿体,2个定位于线粒体,3个是分泌型蛋白;PPO基因在染色体上有串联重复和散布两种形式;9个基因具有内含子,聚类结果显示可以将它们分为6个类型,每个基因类型在进化过程中都发生过基因倍增和丢失;同型基因内含子的位置和大小具有相似性。这些结果揭示蔷薇科植物PPO基因内含子是伴随着基因倍增产生的,基因倍增也是推动PPO基因多样化的重要动力,PPO基因倍增和丢失差异导致PPO基因数量在不同物种之间产生差异。

There are many important fruit plants such as apple, pear, strawberry, blackberry, peach in Rosaceae.They were liable to occurrence enzymatic browning caused by polyphenol oxidase, which result in lots of economics loss. For further analysis PPO, PPO genes were compared by genomic level among five Rosaceae plants. PPO genes were identified and those genes were anchored in chromosome, encoding proteins subcellular location, intron characters, gene duplication and loss, gene phylogeny were analyzed using comparative genomic methods. From five the plants, 42 genes were identified, of which six genes were deduced pseudogenes, 31 genes encoding proteins were located in chloroplast, two were located in mitochondria, three were secretory protein. PPO genes were anchored with tandem repeat or scatter. Phylogenetic trees showed that all these PPO genes could be classed into six types, and genes duplication and loss was occurred for each type in history. There were nine intron-PPO genes and the position and length of intron from the same type PPO gene were similar. In conclusion, the appear of PPO genes intron was an accompany to gene duplication, and PPO genes polymorphism was also caused by gene duplication. The main reason of PPO genes copy variation is gene duplication and loss with plant evolution in Rosaceae.