Trehalose metabolism in sugar sensing and plant development

Trehalose (alpha-D-glucopyranosyl-[1,1]-alpha-D-glucopyranoside), a non-red ucing disaccharide, is common in lower organisms such as bacteria, fungi an d invertebrates. In higher plants, trehalose is generally not accumulated a nd is even considered to be toxic. Recently, genes for trehalose metabolism have, however, been identified in higher plants and characterized by expre ssion studies and functional complementations of corresponding yeast mutant s. Interestingly, data obtained from plants externally supplied with trehal ose or from transgenic plants expressing trehalose biosynthesis genes from microorganisms point towards a role of trehalose, or intermediates of its m etabolism, in sugar sensing and development. These findings may open up new perspectives for engineering the sugar sensing system in plants. Here, we discuss results concerning trehalose as a regulator of the carbohydrate all ocation, system of the plant and possible mechanisms by which trehalose mig ht interfere with the sugar sensing mechanisms and other signal transductio n pathways. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.