Malonyltransferase acting on xenobiotic glucosides. Has activity toward 2-Naphthol glucoside (2NAG), 1-Naphthol glucoside (1NAG), kaempferol 7-O-glucoside, hydroxycoumarin glucosides and phenol-glucosides, but not toward kaempferol 3-O-glucoside or daidzin. Prefers phenol glucosides rather than naphtol glucosides. In vivo, seems to be involved in the malonylation of 4-methylumbelliferone glucoside or 4-nitrophenyl glucoside while PMAT1 would be involved in the malonylation of 2-Naphthol glucoside. a flavonol 7-O-beta-D-glucoside + malonyl-CoA = a flavonol 7-O-(6-O-malonyl-beta-D-glucoside) + CoA Up-regulated by high sucrose and by low phosphate stresses. Belongs to the plant acyltransferase family. Phenolic glucoside malonyltransferase subfamily.