Identification of new transposable elements in the mutable alleles for flower variegation in the Japanese and common morning glories and transposition of the maize Ac/Ds elements in transgenic rice plants.

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The Japanese Morning glory (Pharbitis nil or Ipomoea nil) is a traditional horticultural plant in Japan, and extensive physiological and geneticalstudies on the plant have been conducted. Among several mutable loci that condition variegated flower phenotypes, two mutable alleles, flecked and speckled have been chosenfor molecular elucidation of the variegated phenotypes. The flecked mutant bears white floweres with colored flecks and sectors, and the flecked mutation was found to be caused by integration of the transposable element, Tpn1, into the DFR gene for anthocyanin pigmentation. We have also found that the seckled mutant also carries another transposable element, Tpn2, in the CHI gene for flower Pigmentation.The mutable flaked line of the common morning glory (Pharbitis purpurea or Ipomea purpurea) also bears white flowers with colored flakes and sectors, and the mutable flaked allele is shown to be a newly identified CHS gene having a new transposable element, Tip100, inserted.To understand the behavior of the transposable elements in heterologous system using transgenic plants, we are also characterizing somatic transposition of a non-autonomous Ds element mediated by the active Ac transposase in transgenic rice plants. We are currently investigating on the target selectivity in the somatic transposition of the Ds element.