Evenor, D., Department of Vegetable Crops, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50 250, Israel
Pressman, E., Department of Vegetable Crops, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50 250, Israel
Ben-Yephet, Y., Department of Plant Pathology, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50 250, Israel
Rappaport, L., Department of Vegetable Crops, University of California, Davis, CA, United States

Somaclonal variants were used for selection toward Septoria apiicola Speg. resistance in celery (Apium graveolens L.). Callus-derived single cells or small clusters were cocultured with a hypovirulent or a normal isolate of Septoria apiicola on solid medium or were cultured in the fungal culture filtrate. Resistant cells were developed that, unlike their susceptible counterparts, were not killed off by the toxic compounds secreted by the fungus. Some of the plants regenerated from these cells showed different degrees of tolerance to S. apiicola in greenhouse tests. Selfing the selected plants yielded tolerant progenies, from which the most tolerant were selected further. Several cycles of coculturing, (or culturing), regeneration and selection were made. As these cycles progressed, the percentage of cells surviving the p-toxin increased, indicating a continual positive response to selection for at least three cycles. © 1994 Kluwer Academic Publishers.