Effect of inhibition of phenylpropanoid biosynthesis on peroxidase and IAA-oxidase activities and auxin content in alfalfa suspension cultures

The inhibition of phenylpropanoid biosynthesis: by 2-aminoindan-2-phosphoni c acid (AIP) in alfalfa suspension cultures (Medicago sativa L.) was associ ated with a marked decline in the content of cinnamic acid derivatives duri ng the whole subculture interval. The levels of all investigated forms of p henolic acids in AIP-treated cells were lower than those of control with th e exception of free phenolic acids on days 1 and 2. The dynamics of free IA A content in AIP-treated cells was similar to that of the control but its p eak was significantly lower. The auxin content in AIP-treated cells on days 9 and 11 represented only 35 and 40 % of control values, respectively. AIP -treatment stimulated soluble peroxidase (EC 1.11.1.7) activity in the firs t 2 d after cell inoculation. Time-course of soluble IAA-oxidase activities was similar to that of soluble peroxidases (with the exception of the drop in peroxidase activity on day 3) but beginning day 6, the enzyme activitie s in AIP-treated cells were significantly lower until the end of the subcul ture interval. (C) 2000 Editions scientifiques et medicales Elsevier SAS.