PRODUCTION AND TRANSFORMATION OF CONIDIA OF VENTURIA-INAEQUALIS

High yields of conidia of Venturia inaequalis were produced from eithe r mycelial fragments or conidia on cellophane-covered surfaces of agar media incubated under continuous near-ultraviolet light. Optimal cond itions required a cellophane-covered surface of potato-dextrose agar i n combination with light and incubation for 1 wk. The procedure repres ents a convenient techique for the mass-production of clonal and steri le V. inaequalis conidia. Conidia were biolistically transformed to hy gromycin B resistance with a plasmid (pOHT) containing a bacterial pho sphotransferase gene spliced between regulatory elements from Aspergil lus nidulans. Southern hybridization analysis showed that the plasmid was incorporated into heterologous regions of the genome. Hygromycin B -resistant transformants were mitotically stable during nonselective p ropagation. The heterologous gene conferring hygromycin B resistance w as expressed during early stages of conidia germination and during veg etative growth of mycelium.