Isolation of a Suppressor-mutator/Enhancer-like transposable element, Tpn1, from Japanese morning glory bearing variegated flowers.

Abstract

The Japanese morning glory has an extensive history of genetic studies. Many mutants in the colors and shapes of its flowers and leaves have been isolated since the 17th century, and more than 200 genetic loci have been localized for the 10 linkage groups. They include over 20 mutable loci, several with variegated flower phenotypes. In a line of Japanese morning glory bearing variegated flowers called flecked, a transposable element of 6.4 kb, termed Tpn1, was found within one of the anthocyanin biosynthesis genes encoding dihydroflavonol-4-reductase (DFR). The 6.4-kb element carries 28-bp perfect terminal inverted repeats, the outer 13 bp being identical to those of the maize transposable element Suppressor-mutator/Enhancer. It is flanked by 3-bp direct repeats within the second intron of the DFR gene, 9 bp upstream of the third exon. When somatic and germinal excision occurs, it produces excision sequences characteristic of plant transposable elements. Cosegregation data of the variegated flower phenotype and the DFR gene carrying Tpn1 indicated that the mutable phenotype is due to excision of Tpn1 from the DFR gene. Sequences homologous to Tpn1 are present in multiple copies in the genome of Japanese morning glory.

Transcriptome Analysis of Differentially Expressed Genes Relevant to Variegation in Peach Flowers

“…Much genetic evidence supports the hypothesis that flower variegation is caused by transposable elements inserted into structural genes or regulatory elements related to anthocyanin synthesis [26]–[28]. The different transcript levels detected in this study for structural genes and TFs might be due to insertions of transposable elements.…”

A bHLH transcription factor, DvIVS, is involved in regulation of anthocyanin synthesis in dahlia (Dahlia variabilis)

“…The insertion generated a 3 bp (TGG) target site duplication (TSD), similar to the TSD generated by other CACTA-type transposable elements (Inagaki et al , 1994; Zabala and Vodkin, 2008; Xu et al , 2010). It also contained an ORF for antisense orientation (Fig.…”

Genome sequence and analysis of the Japanese morning glory Ipomoea nil

“…Mutants carrying mutable ct alleles showing somatic reversion to the wild type were reported in the 1930s; however, existing ct mutants showed no mutable phenotypes31. The ct locus was mapped on LG5 of the classical linkage map and was located 1.2 cM from the A3 locus for the anthocyanin biosynthesis gene616. It can be presumed that the CONTRACTED ( CT ) gene is a brassinosteroid (BR) biosynthesis gene, because BR application rescued the deficiency of ct and kobito ( kbt ) double mutants32.…”

“…Our recent studies have revealed that many of these mutant lines have been the result of mutagenic activity by Tpn1 family transposons4678910. These transposons are class II elements and members of En/Spm or CACTA superfamily that can transpose via a cut-and-paste mechanism.…”

“…TnpA and TnpD bind to the sub-terminal repetitive regions (SRRs) and terminal inverted repeats (TIRs) of En/Spm , respectively11. The copy number of the Tpn1 family was estimated to be 500–1,000, and almost 40 copies have been characterized46789101213. All of the transposons characterized thus far are non-autonomous elements, and no elements encoding intact transposase genes have been identified.…”