Temporal and Hormonal Control of P-1, 3-Glucanase

The endo-,-1l,3-glucanase (-3-1,3-glucan 3-glucanhydrolase, EC 3.2.1.6) extracted from Phaseolus vulgaris L. cv. Red Kidney had a pH optimum of 5 and a temperature optimum of 50 C. Excision of plant tissue resulted in an increase in ,l-1,3-glucanase activity after a 6-hour lag period. The increase could be prevented by indole-3-acetic acid, gibberellic acid, and cytokinins. Ethylene (half-maximal concentration = 0.1 microliter/liter) promoted the synthesis of 3-1,3-glucanase, and 10% CO2 overcame some of the ethylene effect. Cycloheximide prevented the induction of l-1,3-glucanase, but actinomycin D and chromomycin A3 had only a partial effect. The amount of callose in sieve tube cells correlated with levels of f-1,3-glucanase, suggesting that this enzyme played a role in the degradation of 3-1,3-glucans.