Effect of culture medium and illumination on the acid invertase activity in callus of Medicago strasseri

The different acid invertase activity (total, soluble, wall-bound and extra cellular) in calli induced on explants (cotyledon, petiole, hypocotyl and l eaf) originated from Medicago strasseri seedlings were evaluated. In cultur es subjected to 16 h photoperiod, the highest total, soluble and extracellu lar activities were found in calli from leaves cultured in medium 12 (MS wi th 0.01 mg.dm(-3) (0.045 mu M) of TDZ), elevated amounts of total and wall- bound invertase being found in calli induced on petioles in 12G medium (MS with 0.01 mg.dm(-3) (0.045 mu M) TDZ and 3.104 mg.dm(-3) glycerol). In cult ures maintained in darkness, the activity detected was lower than that obse rved in cultures under light conditions. The highest amounts of enzyme was bound in calli cultured on medium 12 (total and extracellular invertase) -l eaves- and medium 12D (MS with 0.001 mg.dm(-3) (0.0045 mu M) TDZ) (soluble invertase) -using hypocotyls. In general, the different forms of invertase activity studied seem to appear in greatest amounts in calli induced under light conditions using leaves as explant and TDZ as growth regulator.