Methylates the 2'-hydroxyl of isoliquiritigenin and licodione. Does not methylate narigenin chalcone, caffeic acid or daidzein. Involved in the root nodulation initiation by promoting the biosynthesis of nod-inducing molecules. isoliquiritigenin + S-adenosyl-L-methionine = 2'-O-methylisoliquiritigenin + S-adenosyl-L-homocysteine licodione + S-adenosyl-L-methionine = 2'-O-methyllicodione + H(+) + S-adenosyl-L-homocysteine Inhibited by 1 mM Co(2+), Cu(2+), Zn(2+) or Fe(2+). Non-competitively inhibited by S-adenosyl-L-homocysteine. Competitively inhibited by 2'-O-methylisoliquiritigenin. Optimum pH is 9.0. Monomer (PubMed:1731632). Homodimer (PubMed:11224575). Roots (at protein level). Expressed mainly in roots, and to a lesser extent in root nodules. In the roots, expression is not detected in the root tip or the cells immediately behind the tip, but is detected in tissues starting 1.5-2.0 mm distal to the root tip. Detected in the epidermal and cortical cells of 2 day old roots, with lower levels in vascular tissue. Levels are highest one week after planting. By fungal elicitor. Belongs to the class I-like SAM-binding methyltransferase superfamily. Cation-independent O-methyltransferase family. COMT subfamily.