Leakage of hexose phosphates from the maize scutellum

Abstract

Maize seedlings were incubated at room temperature in the dark with their scutella immersed in fructose solutions. Hexose phosphates and sucrose leaked from these scutella when the root-shoot axes were removed and the scutella placed in water at 1°. Considerable quantities of mannose-6-phosphate (M6P) accumulated in the scutella during incubation of seedlings in mannose or mannose plus fructose solutions; M6P leaked from the scutellum only after removal of the root-shoot axis. During a 4-hr period at 1°, the leakage of newly synthesized sucrose was proportionately greater than the leakage of newly synthesized M6P. The leakage of hexose phosphates at 1° only after removal of the root-shoot axis is additional support for the contention that leakage takes place in a mass flow of solution which empties into the bathing solution through the cut ends of the phloem and which originates in the mesophyll parenchyma cells.