VIEW ARTICLE

Techniques

Production and Transformation of Conidia of Venturia inaequalis. D. M. Parker, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; U. W. Hilber(2), M. Bodmer(3), F. D. Smith(4), C. Yao(5), and W. Köller(6). (2)(3)Department of Plant Pathology, Swiss Federal Research Station, 8820 Wädenswil, Switzerland; (4)Department of Horticultural Sciences, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; (5)(6)Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456. Phytopathology 85:87-91. Accepted for publication 7 October 1994. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/Phyto-85-87.

High yields of conidia of Venturia inaequalis were produced from either mycelial fragments or conidia on cellophane-covered surfaces of agar media incubated under continuous near-ultraviolet light. Optimal conditions required a cellophane-covered surface of potato-dextrose agar in combination with light and incubation for 1 wk. The procedure represents a convenient techique for the mass-production of clonal and sterile V. inaequalis conidia. Conidia were biolistically transformed to hygromycin B resistance with a plasmid (pOHT) containing a bacterial phosphotransferase gene spliced between regulatory elements from Aspergillus 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 propagation. The heterologous gene conferring hygromycin B resistance was expressed during early stages of conidia germination and during vegetative growth of mycelium.