Isolation and Purification of a Factor from Pseudomonas solanacearum That Induces a Hypersensitive-like Response in Potato Cells. Yong Huang. Department of Plant Pathology and Plant Disease Resistance Unit, University of Wisconsin, Madison, 53706 U.S.A. John P. Helgeson(2), and Luis Sequeira(1). (1)Department of Plant Pathology and Plant Disease Resistance Unit, and (2)U.S. Department of Agriculture, Agricultural Research Service, University of Wisconsin, Madison, 53706 U.S.A. MPMI 2:132-138. Accepted 16 February 1989. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1989.

Callus tissues derived from bacterial wilt-resistant or-susceptible clones of Solanum phureja responded differentially to inoculation with strains of Pseudomonas solanacearum. Calli from resistant clones exhibited rapid browning followed by death of the cells, whereas calli from susceptible clones retained their normal appearance for 48 hr after inoculation. Similarly, leaves from resistant clones exhibited a typical hypersensitive response (HR), whereas those from susceptible clones remained symptomless for 48 hr after inoculation. When inoculated with one particular mutant strain (B1), death of callus cells from the potato clone C-3 appeared to be caused by a bacterial protein that is excreted in increased amounts when the bacteria are in contact with plant tissues. This protein was purified by ion exchange, gel permeation, and affinity chromatography. It has a high proline and glycine content, is highly basic (pI = 9.15), and has a mass of approximately 60 kDa. The protein causes rapid browning of callus tissue, rapid death of suspension-cultured cells, and a typical HR in leaves of potato clone C-3.