STABILITY AND MODULATED EXPRESSION OF A HYGROMYCIN RESISTANCE GENE INTEGRATED IN BOTRYTIS-CINEREA TRANSFORMANTS

When transformation of Botrytis cinerea occurred in mononucleated prot oplasts the hygromycin resistance phenotype was stable and integrated plasmid DNA although rearranged was transmitted through meiosis. We ob served that transformants were often heterokaryotic and using serial c onidial transfer, we showed failure of expression of the entire copies of integrated plasmids in some conidial isolates. A non-Mendelian seg regation of the hygromycin resistance phenotype was observed in most c rosses between these transformants and sensitive strains. However, a 1 :1 segregation ratio of plasmid DNA hybridisation was observed. Mechan isms of gene silencing in B. cinerea, in both the asexual and the sexu al cycle, are discussed.