Allelopathy Journal

The phytotoxic mechanism of mimosine and its effects on phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) and peroxidase (POD, EC 1.11.1.7) activities as well as lignin content in soybean (Glycine max (L.) Merr.) roots were investigated. Seedlings (3-d-old) were cultivated in half-strength Hoagland nutrient solution (pH 6.0) with or without 0.05 to 1.0 mM mimosine in a growth chamber (25°C, 12/12 h⁻¹ light/dark photoperiod, irradiance of 280 μmol m⁻² s) for 24 h. In general, length and fresh and dry weights of roots decreased in response to mimosine. Root growth inhibition has been associated with reduction in PAL and POD activities and lignin content. These findings suggest that PAL and POD enzymes are responsible for the mimosine allelochemical action.