Poster: Regulation of gene expression

Abs # 792: Unstable double flower mutant fp harboring an insertion of Helitron-related transposable element in the common morning glory

Presenter:	Nitasaka, Eiji , enitascb@mbox.nc.kyushu-u.ac.jp
Authors	Nitasaka, Eiji  (A)   Iwasaki, Mayumi  (A)   Coberly, Caitlin  (B)
Affiliations:	(A): Kyushu University (B): Duke University

A double flower mutant, flora pleno (fp) of the common morning glory (Ipomoea purpurea) was isolated from a wild population of North Carolina. The mutant phenotype was unstable and various degree double flowers were often observed in a single plant. Stamens were transformed into petals, and were fused with original petals (corolla). The pistil was converted to a thick pistil, separl like organs, and a new flower in weak, intermediate and strong phenotype flowers, respectively. Moreover, single (wild-type) flowers were appeared in a fp mutant plant. Therefore, fp is thought to be a loss-of-function mutant of an orthologs of C-function MADS-box gene DUPLICATED (DP) isolated in the Japanese morning glory (I. nil). In the fp mutant, the transcription level of another C-function MADS-box gene PN was normal, but the DP transcript was not detected. Analysis of the genomic region revealed that there was a novel insertion sequence in the second intron of DP-ortholog (FP). This 12.7 kb insertion sequence has the striking similarity to the recently described DNA helicase-bearing transposable elements Helitrons, and it was designated as Helip1. The unstable phenotype of fp mutation is possibly caused by the frequent somatic excision of Helip1 in FP gene that supplies some extent of wild-type FP products. This was confirmed by a finding that wild-type DNA fragment of FP was detected by PCR in the fp mutant background. This is the first report for an active Helitron-related transposable element in any organism.