Abstract: Uptake, translocation, and distribution of ¹⁴C-labelled oligosaccharides in watermelon seedling were investigated by the means of radioactive isotope tracer. The autoradiograph experiment showed that oligosaccharides could fast be absorbed by the watermelon seedling after it was supplied through leaf or root. The translocation of the oligosaccharides in leaf trended from the margin to the center. After treatment by leaf-dripping for 8 h and treatment by root-dipping for 24 h, the oligosaccharides translocated and distributed in whole watermelon seedling, indicating that ¹⁴C-labelled oligosaccharides have a strong ability to spread and translocate downwards or upwards in the seedling. During 4 h to 120 h after the treatment by leaf-dripping, the specific activity of root, others(stem and indirectly treated leaf in the whole seedling) transformed from 0.18×10⁵ and 23.08×10⁵ Bq/kg to 0.32×10⁵ and 3.02×10⁵ Bq/kg, respectively. As a whole, the trend of distribution and downward translocation was weak. During 4 h to 120 h after the treatment by root-dipping, the specific activity of root, stem, cotyledon, and true leaf transformed from²2.23×10⁵, 2.23×10⁵, 8.33×10⁵ and 12.78×10⁵ Bq/kg to 431.11×10⁵, 42.23×10⁵, 65.57×10⁵ and 78.89×10⁵ Bq/kg, respectively, suggesting a strong accumulation trend above the ground and upward translocation activity of ¹⁴C-oligosaccharides in watermelon seedling.

Key words: C-labelled oligosaccharides, Radioactive isotope tracer, Pharmacology, Watermelon seedling, Uptake and translocation