Search for an unknown mobile genetic element controlling expression of genes in phenylpropanoid biosynthesis

虽然转座子被认为存在于几乎所有的生物体中，但它们只从少数几种植物中分离出来，并且只在玉米(Zea Mays)和金鱼草(金鱼草)两种植物中得到了遗传和分子水平的特征。它们转座、影响基因表达和促进DNA重排的能力导致遗传不稳定。我们正试图从日本传统园艺植物中鉴定出新的转座元件，包括日本牵牛花(Pharbitisnil)、牵牛花(Ipomoea Purpurea)和杜鹃花(Rhododuron)。从一株日本牵牛花中发现了一个6kb的插入片段，命名为Tpn1(转座子Pharbitis nil one)，用于花青素的生物合成。其末端反向重复序列和靶重复序列的长度表明它是玉米Spm/en家族的一个新的转座元件。Tpn1元件的末端区域含有10个碱基重复序列，可能是转座酶结合位点。这些区域还携带104个和123个碱基的串联直接重复序列。转座酶结合区的组织结构与已知的植物转座元件有很大的不同。我们还在一个具有可变花型的牵牛花系中发现了花青素生物合成基因的DNA重排。

Although transposable elements are believed to exist in virtually every organism, they have been isolatad from only a few plants and have been characterized at genetic and molecular levels in only two plants, maize (Zea mays) and snapdragon (Antirrhinum majus). Their ability to transpose, affect gene expression and promote DNA rearrangements causes genetic instability.We are trying to identify and characterize new transposable elements from traditional horticultutral plants bearing variegated flowers in Japan which include Japanese morning glory (Pharbitisnil), morning glory (Ipomoea purpurea) and azalea (Rhododendron). From a line of the Japanese morning glory producing variegated flowers called "flecked", we have found a 6 kb insertion, termed Tpnl (Transposon Pharbitis nil one ) within the DFR gene for anthocyanin pigment biosynthesis. Its terminal inverted repeats and length of target duplications indicate that it is a new transposable element belonging to the maize Spm/En family. The terminal regions of the Tpnl element contain 10 bp repeats which are likely to be transposase binding sites. The regions also carry 104 bp and 123 bp tandem direct repeats. The organization of the putative transposase binding region differs significantly from the known plant transposable elements.We have also identified DNA rearrangements in a gene for anthocyanin biosynthesis in a line of morning glory bearing mutable flower phenotype.