Each year brings new facts concerning multiple roles of sugar pathways in plant metabolism. One of them--the trehalose pathway--has been shown to play a role in stress signalling. The last enzyme of this pathway--trehalase--has been proven to be strongly expressed in guard cells. Modifications of its abundance cause changes in stomatal closure and response to abscisic acid. Our phenotypical studies of different mutants of Arabidopsis thaliana and Musa have enabled us to propose a new function of trehalase. It might play a role in the feedback of sucrose as a closing signal for stomata in reaction to an efficient photosynthesis. To characterize the phenotype we measured: the dynamic cumulative water loss, the dynamic leaf surface temperature, and the stomatal conductance. Based on the obtained results we have determined the time points for a proteomics study. The exact role of trehalase and related proteins in the proposed mechanism will be defined with multiple analysis including mass spectrophotometry and enzymatic activities. The samples will be collected from a wide type of plants including model organism (Arabidopsis--wild type, trehalase mutant plants) and crops (banana). The final results will shed light on the complete role of trehalase and the feedback pathway.