抄録
The phloem exudate (PE) prepared from cotyledons of Ipomoea tricolor seedlings that had been exposed to a single 16 h dark period induced flowering in cultured apices excised from non-induced seedlings. When the PE was separated to 4 fractions by dialysis, low (‹1,000) and high (10,000–25,000) molecular weight (HMW) fraction had flower-inducing activity. To characterize the HMW fraction, the fraction was treated with some disintegrating enzymes. The flower-inducing activity was disappeared by proteinase K treatment. Therefore, HMW active substance(s) may be protein. When the HMW fraction was fractionated by gel filtration chromatography, the molecular weight of active fraction was ca. 23,000 dalton. Simultaneous addition of low molecular weight fraction could not promote inducing activity of HMW fraction. The PE prepared from I. tricolor seedlings grown under continuous light conditions (CL-PE) inhibited flowering in cultured apices excised from induced seedlings. When the CL-PE was added to assay medium simultaneously with HMW fraction, flowering was inhibited.
