We established the adventitious-root cultures of Iris germanica, a monocotyledonous plant known for isoflavonoid production. Irigenin (5,7,3Ј-trihydroxy-6,4Ј,5Ј-trimethoxyisoflavone) and iristectorigenin A (5,7,3Ј-trihydroxy-6,4Ј-dimethoxyisoflavone) along with their 7-O-b-D-glucosides, iridin and iristectorin A, respectively, were found as the major components in adventitious roots in the liquid medium, and the total isoflavone content was about 3.6 mmol per g fresh weight in 3-week-old

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... s, which was much higher than the 0.7 mmol per g dry weight in the rhizome previously reported (Ali et al. 1983 Phytochemistry 22: 2061. Abiotic stress was applied by addition of 3 mM cupric chloride (CuCl 2 ) to the liquid medium. The isoflavone glucoside content was increased during the initial 6 h of CuCl 2 treatment, which was followed by a decrease; the aglycone level continued to increase throughout the 48 h of treatment. The decrease in glucoside content was negatively correlated with the increase in aglycone content between 6 and 48 h. The total isoflavone content (glucosidesϩaglycones) at 6 h after the start of CuCl 2 treatment was 1.4-fold the initial value, and nearly the same content was maintained for 48 h. Thus, the main effect of CuCl 2 treatment appeared to be the induction of hydrolysis of isoflavone glucosides. A cDNA of chalcone synthase was cloned, and the mRNA was expressed in the culture producing isoflavones.