2.1.1.150	S-adenosyl-L-methionine + 7,4'-dihydroxyisoflavone	i.e. daidzein	
2.1.1.150	S-adenosyl-L-methionine + 7,4'-dihydroxyisoflavone	i.e. daidzein, about 20% of the activity with 6,7,4'-trihydroxyisoflavone (i.e. glycitein). Key enzyme in the biosynthesis of the phytoalexin medicarpin in Medicago sativa	
2.1.1.150	S-adenosyl-L-methionine + 7,4'-dihydroxyisoflavone	i.e. daidzein. 4'-O-Methylation of an isoflavonoid intermediate is a key reaction in the biosynthesis of the phytoalexin medicarpin in legumes. However, isoflavone O-methyltransferase from alfalfa converts the isoflavone daidzein to 7-O-methyldaidzein (isoformononetin) in vitro as well as in vivo in unchallenged leaves of transgenic alfalfa ectopically expressing IOMT. In contrast, elicitation of IOMT-overexpressing plants with CuC2 or infecting these plants with Phoma medicaginis leads to greater accumulation of formononetin (4'-O-methyl daidzein) and medicarpin in the leaves than does elicitation or infection of control plants, and no isoformononetin is detected	
2.1.1.150	S-adenosyl-L-methionine + 7,4'-dihydroxyisoflavone	i.e. daidzein. The operationally soluble IOMT localizes to endomembranes after elicitation of the isoflavonoid pathway. IOMT colocalizes with the endoplasmic reticulum–associated isoflavone synthase cytochrome P450 to ensure rapid B-ring methylation of the unstable 2,7,4'-trihydroxyisoflavanone product of isoflavone synthase, thereby preventing its dehydration to daidzein and subsequent A-ring methylation by free IOMT. In this way, metabolic channeling at the entry point into isoflavonoid phytoalexin biosynthesis protects an unstable intermediate from an unproductive metabolic conversion