Polyphenol oxidase (PPO) in wheat and wild relatives: molecular evidence for a multigene family
Polyphenol oxidase (PPO) in wheat and wild relatives: molecular evidence for a multigene family
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DOI：
10.1007/s00122-007-0514-4
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发表时间：
2007-05-01
影响因子：
5.4
通讯作者：
Morris, Craig F.
中科院分区：
文献类型：
--
作者：
Massa, Alicia N.;Beecher, Brian;Morris, Craig F.
小麦多酚氧化酶（PPO）是导致亚洲面条和其它小麦制品变色的布朗宁反应的主要原因。据推测，编码小麦PPO的基因可能已经通过基因复制进化成一个多基因家族。本研究对二倍体小麦（Triticum monococcum，T. urartu、粗山羊草Aegilops tauschii和山羊草Ae. speltoides）、四倍体（T. turgidum，亚种dicoccoides和durum）和六倍体（T. aestivum栽培品种Klasic和ID377s）小麦物种的PPO基因的结构和组织获得更好的理解。从该基因的高度多态性和系统发育信息区域扩增DNA片段。结果，我们获得了高度区分的序列。从T. monococcum，提供了基因复制事件（旁系同源基因座）的证据。此外，获得的面包和硬粒小麦的序列的数量高于预期数量的正交位点。序列比较揭示了核苷酸和结构的多样性，并检测到五个序列内含子类型，所有具有共同的插入位置。这被推测为与先前报道的小麦PPO的内含子2同源。Stowaway家族的一个MITE解释了五个间插序列之间的主要差异，并且是T.普通小麦克拉西奇核苷酸和结构的多样性，以及良好解决的系统发育树，提供了分子证据，以支持假设的PPO多基因家族结构和组织。
Wheat polyphenol oxidase (PPO) is the major cause of browning reactions that discolor Asian noodles and other wheat products. It has been hypothesized that genes encoding wheat PPOs may have evolved by gene duplication into a multigene family. Here we characterized PPO genomic sequences from diploid (Triticum monococcum, T. urartu, Aegilops tauschii, and Ae. speltoides), tetraploid (T. turgidum, subspecies dicoccoides and durum) and hexaploid (T. aestivum cultivars Klasic and ID377s) wheat species to gain a better understanding of the structure and organization of PPO genes. DNA fragments were amplified from a highly polymorphic and phylogenetic informative region of the gene. As a result, we obtained highly discriminative sequences. Three distinct PPOs, obtained from the A genome of T. monococcum, provided evidence for gene duplication events (paralogous loci). Furthermore, the number of sequences obtained for bread and durum wheat was higher than the expected number of orthologous loci. Sequence comparison revealed nucleotide and structural diversity, and detected five sequence intron types, all with a common insertion position. This was hypothesized to be homologous to that of intron 2 of previously reported wheat PPOs. A MITE of the Stowaway family accounted for the major difference between the five intervening sequences, and was unique to T. aestivum cv. Klasic. Nucleotide and structural diversity, together with well-resolved phylogenetic trees, provided molecular evidence to support the hypothesis of a PPO multigene family structure and organization.