HIGH-RESOLUTION HISTOGRAPHICAL MAPPING OF GLUCOSE-CONCENTRATIONS IN DEVELOPING COTYLEDONS OF VICIA-FABA IN RELATION TO MITOTIC-ACTIVITY ANDSTORAGE PROCESSES - GLUCOSE AS A POSSIBLE DEVELOPMENTAL TRIGGER

Previous studies provided evidence that the carbohydrate status trigge rs developmental processes in the growing cotyledons of Vicia faba. We describe here the high-resolution mapping of glucose concentrations i n tissue sections of developing faba bean cotyledons by quantitative b ioluminescence and single-photon imaging. Patterns of local glucose di stributions are compared with tissue cell type, mitotic index and the distribution pattern of starch. During cotyledon differentiation, grad ients in the glucose concentration emerge which are related to the par ticular cell type. Higher concentrations are found in non-differentiat ed premature regions of the cotyledon whereas mature starch-accumulati ng regions contain particularly low concentrations of glucose. In addi tion, glucose concentration is correlated to mitotic activity. The glu cose distribution pattern is therefore related to the developmental gr adient. Our data provide for the first time evidence for steep glucose gradients across developing plant embryos and favour the idea that su gar gradients may have morphogenic functions in developing cotyledons.