EFFECT OF 2 ISOLATES OF TRICHODERMA-HARZIANUM ON THE ACTIVITY OF HYDROLYTIC ENZYMES PRODUCED BY BOTRYTIS-CINEREA

Two isolates of Trichoderma harzianum (T39 a biocontrol agent, and NCI M 1185) were tested for their capacity to reduce the level of hydrolyt ic enzymes produced by Botrytis cinerea both in vitro and in vivo, and to inhibit infection caused by B. cinerea conidia. The hydrolytic enz ymes studied were cutin esterase, polygalacturonases (PG), pectin meth yl esterase (PME), pectate lyase (PL) and carboxymethyl cellulase (CMC ase). On the surface of bean (Phaseolus vulgaris) leaves, isolate T39 inhibited germination of B. cinerea conidia and subsequent disease dev elopment significantly better than isolate NCIM1185. The levels of the various hydrolytic enzymes were reduced when B. cinerea was grown eit her with a T. harzianum isolate in liquid culture or on the surface of bean leaves. T39 reduced enzyme levels by about 64, 80, 25, 77, 42 an d 23% for cutin esterase, exoPG, endoPG, PME, PL and CMCase, respectiv ely. NCIM1185 caused 57, 60, 5, 87 and 11% reduction in the production of cutin esterase, exoPG, endoPG, PME, PL and CMCase, respectively. H owever, NCIM1185 enhanced the production of PL when it was grown with B. cinerea in liquid culture medium. On the surface of bean leaves, T3 9 was the better inhibitory agent. The only exception was CMCase, the presence of which was not inhibited by either isolate. Cutin esterase, exo and endoPG, PME and PL of B. cinerea on bean leaves were reduced in the presence of T39 by ca 20, 95, 100-50, 100 and 95%, respectively . The importance of reduced enzyme activity of B. cinerea in the bioco ntrol. activity of T. harzianum is discussed. (C) 1998 Academic Press Limited.