Hypothetical model of miRNAs regulation in triterpenoid biosynthesis pathway. AACT, acetyl-CoA C-acetyltransferase; HMGS, 3-hydroxyl-3-methylglutaryl-CoA synthase; HMG-CoA, 3-hydroxy-3-methylglutaryl-CoA; HMGR, 3-hydroxyl-3-methylglutaryl-CoA reductase; MVA, mevalonate; MVK, mevalolate kinase; MVAP, 5-metholvalic acid phosphoric; PMK, phosphoric acid valate kinase; MVAPP, 5-metholvalic acid pyrophosphoric acid; MVD, 5-hydroxyvalerate decarboxylase; G3P, 3-glyceraldehyde phosphate; DXS, 1-deoxy-D-xylulose-5-phosphate synthetase; DXP, 1-deoxy-D-xylulose-5-phosphate; DXR, 1-deoxy-D-xylulose-5-phosphate reductoisomerase; MEP, 2-C-methyl-D-erythritol-4-phosphATE; MCT, 4-cytidine diphosphate-2-C-methyl-D-erythritol synthetase; CDP-ME, 4-cytidine diphosphate-2-C-methyl-D-erythritol; CMK, 4-cytidine diphosphate-2-C-methyl-D-erythritol kinase; CDP-ME2P, 4-cytidine diphosphate-2-C-methyl-D-erythritol-2-phosphate; MDS, 2-C-methyl-D-erythritol-2,4-cyclic phosphate synthetase; MEcPP, 2-C-methyl-D-erythritol-2,4-cyclic phosphate; HDS, 4-hydroxy-3-methylbut-2-enyl diphosphate synthase; HMBPP, 4-hydroxy-3-methylbut-2-enyl pyrophosphate; HDR, 4-hydroxy-3-methylbut-2-enyl diphosphate reductases; IDI, isopentenyl pyrophosphate isomerase; IPP, isopentenyl pyrophosphate; DMAPP, dimethylallyl pyrophosphate; GPP, geranyl pyrophosphate; GPS, geranylpyrophosphate synthetase; FPS, farnesyl pyrophosphate synthetase; FPP, farnesyl pyrophosphate; SS, squalene epoxidase; β-AS, beta-amyrin synthase; LUS, lupeol synthase; CYP450, cytochrome P450; UGT, uridine diphosphate-dependent glycosyltransferases.