Involved in the regulation of trehalose content by hydrolyzing trehalose to glucose. alpha,alpha-trehalose + H2O = alpha-D-glucose + beta-D-glucose Has extracellular activity when expressed in yeast. Highly expressed in flowers. Expressed at low levels in leaves and stems. No visible phenotype under normal growth conditions, but plants accumulate high levels of trehalose and starch. Belongs to the glycosyl hydrolase 37 family.