Heterologous expression of a basic elicitin from Phytophthora cryptogea in Phytophthora infestans increases its ability to cause leaf necrosis in tobacco

1 Fungal and Bacterial Plant Pathology Department, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK 2 Station de Botanique et de Pathologie Végétale, INRA, BP 2078, F-06606 Antibes, France ABSTRACT Summary: The cry-b sequence, encoding a basic elicitin (cryptogein B) from Phytophthora cryptogea , was co-transformed into Phytophthora infestans. The copy number of the cry-b sequence varied in co-transformants. Nevertheless, in all cases the alien elicitin gene was transcribed, translated and the protein secreted in vitro from such transformants. Moreover, the secreted cryptogein B from P. infestans co-transformants increased their ability to cause a hypersensitive-response-like necrosis of tobacco leaves. It was thus concluded that the transfer of a single gene encoding a basic elicitin from one Phytophthora species to another can dramatically alter the phenotypic interaction of the transformed species with tobacco. Author for correspondence: Paul R. J. Birch. Tel: +44 1382 562731. Fax: +44 1382 562426. e-mail: pbirch@scri.sari.ac.uk Keywords: co-transformation, elicitin gene, heterologous expression, Phytothora, tobacco necrosis