Transformants ofTrichoderma longibrachiatumoverexpressing the beta-1,4-endoglucanase geneegl1show enhanced biocontrol ofPythium ultimumon cucumber

Nine transformants ofTrichoderma longibrachiatumwith extra copies of theegl1gene were studied for mitotic stability, endoglucanase production, and biocontrol activity againstPythium ultimumon cucumber seedlings. The transformants showed a significantly higher level of expression of theegl1gene in comparison to the wild type under both inducing and noninducing growth conditions. Transformants with theegl1gene under the control of a constitutive promoter had the highest enzymatic activity. Both the endoglucanase activity and the transforming sequences were stable under nonselective conditions. When applied to cucumber seeds sown inP. ultimum-infested soil,T. longibrachiatumtransformants with increased inducible or constitutiveegl1expression generally were more suppressive than the wild-type strain.