Phenolic glucoside malonyltransferase that neutralizes phenolic glycosides in host plants (PubMed:33770502). Catalyzes the transfer of a malonyl group from malonyl-CoA to the phenolic glycosides, leading to their detoxification (PubMed:33770502). Phenolic glycosides, which are among the most abundant plant secondary metabolites, act as plant defense compounds: they strongly affect growth, development and behavior of insect herbivores (PubMed:33770502). Has malonyltransferase activity against flavonoids kaempferol 3-O-glucoside, kaempferol 7-O-glucoside, isoquercetin (quercetin 3-O-beta-D-glucopyranoside), apigetrin (apigenin 7-O-beta-D-glucoside) and prunin (naringenin 7-O-beta-D-glucoside) (PubMed:33770502). Also has activity toward non-flavonoid rhaponticin, but with lower efficiency (PubMed:33770502). a flavonol 3-O-beta-D-glucoside + malonyl-CoA = a flavonol 3-O-(6-O-malonyl-beta-D-glucoside) + CoA kaempferol 3-O-beta-D-glucoside + malonyl-CoA = CoA + kaempferol 3-O-(6-O-malonyl-beta-D-glucoside) malonyl-CoA + quercetin 3-O-beta-D-glucoside = CoA + quercetin 3-O-(6-O-malonyl-beta-D-glucoside) a flavonol 7-O-beta-D-glucoside + malonyl-CoA = a flavonol 7-O-(6-O-malonyl-beta-D-glucoside) + CoA (2S)-naringenin 7-O-beta-D-glucoside + malonyl-CoA = (2S)-naringenin 7-O-(6-O-malonyl-beta-D-glucoside) + CoA kaempferol 7-O-beta-D-glucoside + malonyl-CoA = CoA + kaempferol 7-O-(6-O-malonyl-beta-D-glucoside) apigenin 7-O-beta-D-glucoside + malonyl-CoA = apigenin 7-O-(6-O-malonyl-beta-D-glucoside) + CoA malonyl-CoA + rhaponticin = 6-O-malonyl-rhaponticin + CoA Expressed in all tissues (PubMed:33770502). Most highly expressed in the abdomen and especially in the gut (PubMed:33770502). Expressed in all developmental stages with higher expression in adults (PubMed:33770502). Also detected in the egg stage to a much lower level (PubMed:33770502). MAT1 protein-coding gene was acquired from plants through a plant-to-insect horizontal gene transfer event. Belongs to the plant acyltransferase family. Phenolic glucoside malonyltransferase subfamily. For the sake of sap - Issue 244 of February 2022