The role of an extracellular chitinase from Trichoderma virens Gv29-8 in the biocontrol of Rhizoctonia solani

The role of extracellular chitinase in the biocontrol activity of Trichoderma vii ens was examined using genetically manipulated strains of this fungus. The T. virens strains in which the chitinase gene (cht42) was disrupted (KO) or constitutively over-expressed (COE) were constructed through genetic transformation. The resulting transformants were stable and showed patterns similar to the wild-type (WT) strain with respect to growth rate, sporulation, antibiotic production, colonization efficiency on cotton roots and growth/survival in soil. Biocontrol activity of the KO and COE strains were significantly decreased and enhanced, respectively against cotton seed ling disease incited by Rhizoctonia solani when compared with the WT strain.