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

虽然转座因子被认为存在于几乎所有生物体中，但它们仅从少数植物中分离出来，并且仅在玉米（Zea mays）和金鱼草（Antirhinum majus）这两种植物中在遗传和分子水平上进行了表征。它们的转座、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的杂色花卉园艺植物中识别和表征新的转座元件，这些植物包括日本牵牛花 (Pharbitisnil)、牵牛花 (Ipomoea purpurea) 和杜鹃花 (Rhododendron)。从产生称为“斑点”的杂色花的日本牵牛花品系中，我们在 DFR 基因内发现了一个 6 kb 的插入，称为 Tpnl（转座子 Pharbitis nil one），用于花青素生物合成。其末端反向重复序列和目标重复长度表明它是属于玉米Spm/En家族的新转座元件。 Tpnl 元件的末端区域包含 10 bp 重复序列，可能是转座酶结合位点。这些区域还携带 104 bp 和 123 bp 串联同向重复序列。假定的转座酶结合区的组织与已知的植物转座元件显着不同。我们还在带有可变花表型的牵牛花品系中鉴定了花青素生物合成基因中的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.