BIOLISTIC TRANSFORMATION OF TRICHODERMA-HARZIANUM AND GLIOCLADIUM-VIRENS USING PLASMID AND GENOMIC DNA

Biolistic (biological ballistic) and protoplast-mediated procedures we re compared as methods for transforming strains of Gliocladium virens and Trichoderma harzianum. For biolistic transformation, conidia were bombarded using a helium-driven biolistic device to accelerate M5 tung sten particles coated with plasmid or genomic DNA. DNA from either sou rce contained a bacterial hygromycin B resistance gene (hygB) as a dom inant selectable marker. The same sources of DNA were also used to tra nsform protoplasts using a standard polyethylene glycol-CaCl2 protopla st fusion protocol. Hygromycin B-resistant (HygB(R)) transformants wer e recovered from all strains, methods, and DNA sources except for geno mic DNA used with the protoplast method. The biolistic procedure was t echnically simpler, and increased transformation frequency and genetic stability in the progeny as compared with the protoplast-mediated tra nsformation. Southern analysis of homokaryotic HygB(R) progenies showe d that the transforming sequences were integrated into the genome of t he recipient strains, and apparently were methylated. This is the firs t study presenting detailed results on biolistic transformation of a f ilamentous fungus.