Trehalose and trehalase in plants: Recent developments

Trehalose is a non-reducing disaccharide consisting of two alpha-glycosidically linked glucose units. It accumulates in many microorganisms and invertebrate animals when they are exposed to various forms of stress, and it may serve as a protectant of enzymes and membranes, particularly under conditions of heat and desiccation stress. Most vascular plants lack the capacity to produce trehalose, except for a small number of desiccation tolerant plants, such as some ferns and the angiosperm Myrothamnus flabellifolia. In contrast, a highly specific trehalase activity has been described in many plants. The enzyme does not cleave other common alpha-glucosides, and it is highly sensitive to the inhibitor validamycin A. Trehalases have been found in various tissues; particularly high activities occur in pollen and legume root nodules. The possible functions of plant trehalase are discussed, focussing on its significance in the interaction of plants with trehalose-accumulating microorganisms.