Sucrose leakage from the maize scutellum

Abstract

Sucrose accumulated in the cytoplasm of mesophyll, parenchyma cells when maize scutella (whole or sliced) were put in concentrated (e.g. 1·0 M) fructose solutions. This accumulated cytoplasmic sucrose leaked from the tissue when the fructose solution was replaced with water or with a more dilute hexitol solution. The amount of leakage was proportional to the concentration difference between the fructose solution bathing the scutellum slices during the sucrose accumulation period and the hexitol solution bathing the slices during the leakage period. Only small amounts of cytoplasmic sucrose leaked from the whole scutellum into water until the root-shoot axis was removed. Other substances also leaked, with sucrose, from the scutellum. Sucrose, nitrogenous compounds, K + and phosphorous compounds leaked in greatest amounts. The results presented are consistent with the ideas of the mass flow hypothesis. In the scutellum system a pressure flow of solution originates in the mesophyll cells, flows from cell to cell through plasmodesmata, into and through the phloem sieve tubes, and, finally, into the bathing solution.