Kapat, A., Department of Plant Pathology, ARO, Volcani Center, P.O.B. 6, Bet Dagan 50250, Israel
Zimand, G., Department of Plant Pathology, ARO, Volcani Center, P.O.B. 6, Bet Dagan 50250, Israel
Elad, Y., Department of Plant Pathology, ARO, Volcani Center, P.O.B. 6, Bet Dagan 50250, Israel

The ability of Botrytis cinerea to produce cutinolytic, pectolytic and cellulolytic enzymes was re-examined in vivo and in vitro. In liquid culture, B. cinerea produced both constitutive and inductive forms of hydrolytic enzymes. The constitutive levels were 44 mU, 720 mU, 1820 mU, 12.0 U and 22.4 mU for cutin esterase, endopolygalacturonase (endoPG), exopolygalacturonase (exoPG), pectin methyl esterase (PME) and pectate lyase (PL), respectively. Unlike the other enzymes, however, carboxymethyl cellulase (CMCase) production was found to be entirely inducible. The enzymes secreted at the germination and germ-tube growth stages, and during subsequent disease development, were quantified simultaneously. Complete germination was observed within 9 h of incubation of B. cinerea on the surface of bean leaves and disease symptoms gradually increased during days 1-6 of the incubation. Significant amounts of all hydrolyric enzymes studied in the early hours and monitored during 6 d of incubation were detected, supporting the possibility of a major role for the enzymes produced by B. cinerea in the development of disease. The amount of cutinase was found to be uniform from the beginning, indicating that this enzyme may have an important role in penetrating the impervious cutin layer. The exoPG level increased from the beginning of incubation whereas that of endoPG started to rise later. PL and PME were also detected on the leaf surfaces. The patterns of in vitro production of exoPG, endoPG and PL correlated with the in vivo production of these enzymes, but there was only partial correlation in the production of PME and no correlation in the patterns of cutinase and CMCase production.