XVI International Botanical Congess

Isoflavonoids are distributed mainly in legumes and play critical roles in plant-microbe interactions. A cytochrome P450, 2-hydroxyisoflavanone synthase (IFS), is the key enzyme of their biosynthesis, catalyzing the hydroxylation and 1,2-aryl migration of flavanones. We obtained a P450 cDNA CYP93C2 from elicited Glycyrrhiza echinata cells producing an isoflavonoid-derived phytoalexin. When the flavanones liquiritigenin and naringenin were incubated with the recombinant yeast microsome expressing CYP93C2, respective major products emerged and were readily converted to the isoflavones daidzein and genistein by acid treatment. Northern blot analysis revealed that the transcripts of CYP93C2 and other P450s (CA4H, F2H [1], I2'H [2]) transiently accumulate upon elicitation. [1, 2] Akashi T et al., (1998) FEBS Lett, 431: 287, BBRC 251: 67.