Induction of stable recombinants of Trichoderma virens with enhanced biocontrol capability using protoplast fusion [electronic resource].

Includes reference.

Two Fungicide tolerant mutants of Trichoderma virens (TVBenR.3 andTVlpR.7) were used as parental strains to improve their antagonistic activity via protoplast fusion. Protoplasts obtained from18-h-old mycelium treated by Novozyme 234 were fused by polyethylene glycol (PEG). The frequency of fusion resulting in double fungicide tolerant isolates was about 0.38 %. Analysis of fusants progeny showed that five fusants out of 21 did not exhibit any segregation but able to grow in the presence of both fungicides, indicating that these colonies are a result of a karyogamy (nuclear fusion). Two fusants resulting from a karyogamy were sable and the other three fusants were the result of temporary nuclear fusion formation that were unstable and did not loss through successive cycles of mitotic division during mycelial growth. Fusants derived from nuclear fusion were tested in vitro. for their antagonistic activities against some plant pathogenic fungi (Pythium altimum, Rhizoctonia solani, Sclerotium rolfsii, and Macrophomina phaseolina). The fusants were generally equal or less active than their parents. Stability of the two double tolerant isolates (TVBenR.3 and TVlpR.7)-was represented by their ability to maintain tolerance to fungicides after three subculturing in the absence of fungicides.

Summary in Arabic.

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