VIEW ARTICLE

A Tissue Culture System for Studying Disease Resistance: the Black Shank Disease in Tobacco Callus Cultures. J. P. Helgeson, Research Plant Physiologist, Pioneering Research Laboratory, Plant Science Research Division, ARS, USDA, and Department of Plant Pathology, University of Wisconsin, Madison 53706; J. D. Kemp(2), G. T. Haberlach(3), and D. P. Maxwell(4). (2)(3)(4)Research Chemist, Research Assistant Plant Physiologist, and Associate Professor, respectively, Pioneering Research Laboratory, Plant Science Research Division, ARS, USDA, and Department of Plant Pathology, University of Wisconsin, Madison 53706. Phytopathology 62:1439-1443. Accepted for publication 29 June 1972. DOI: 10.1094/Phyto-62-1439.

Tobacco tissue cultures were obtained from two genetically similar plants, one resistant and the other susceptible to race 0 of Phytophthora parasitica var. nicotianae. Under certain defined conditions, tissue cultures from the resistant plant were colonized less rapidly and less extensively by race 0 of the pathogen than tissue cultures from the susceptible plant. Race 1 of the fungus, to which both plant clones were equally susceptible, colonized tissue cultures of both lines to a similar extent. Tissue colonization rates increased as incubation temperature was increased from 15 to 32 C. The colonization differential was most apparent from 20-24 C, and negligible at 27-32 C. With the tissue culture line derived from the resistant plant, colonization rates were varied over a wide range, from relatively slow, to colonization rates much faster than in callus tissue from susceptible plants by modification of the hormonal regime of the growth medium. The tobacco tissue culture, P. parasitica var. nicotianae system appears suitable for studying the nature of disease resistance under strictly controlled conditions.