TRANSFORMATION OF BOTRYTIS-CINEREA WITH THE NITRATE REDUCTASE GENE (NIAD) SHOWS A HIGH-FREQUENCY OF HOMOLOGOUS RECOMBINATION

The nitrate reductase (niaD) gene was isolated from the phytopathogeni c ascomycete Botrytis cinerea using a probe obtained by a polymerase c hain reaction (PCR) with degenerate oligonucleotides corresponding to domains conserved among three fungal nitrate reductases. The B. cinere a niaD gene encodes a predicted protein of 907 amino acids and contain s no intron. Nitrate reductase-deficient mutants of B. cinerea have be en isolated. One of them was transformed with the niaD genes of Fusari um oxysporum f.sp. melonis and B. cinerea. The transformation was alwa ys ectopic when the donor DNA originated from F: oxysporum, but there was 80% gene replacement when the donor DNA originated from B. cinerea .