The distribution of the flavanones neohesperidin and naringin has been analyzed during the development of the stem of C. aurantium. Neohesperidin was the most abundant flavonoid. The distribution of both flavanones in stem tissues, their presence in vascular fluids and the absence of 4’-O-methyltransferase activity in these tissues suggest that they are translocated between the different plant organs. The neohesperidin and naringin levels of immature fruits are substantially influenced by the number of leaves in their victinity, the more leaves there are, the greater the total content per fruit. The presence and distribution of neohesperidosides in particular zones of the vascular system of C. sinensis onto which C. aurantium had been grafted suggests that there is flavonoid translocation in the direction of plant growth. The in vitro study of flavonoid diffusion in small sections of C. aurantium stems supports the idea of a mechanism which takes part in the displacement of flavonoids through the plant. A study of neohesperidin and naringin distribution of C. aurantium stems, leaves, flowers and fruits and their relation with the 4’-O-methyltransferase activity observed in these organs suggests that the accumulation of flavonoids is the result of translocation and biosynthesis processes and that the contribution of each process to the overall flavanone content varies during organ development.
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