Structural and Immunochemical Studies on the Phytotoxic Peptidorhamnomannan of Ceratocystis ulmi

Abstract

A wilt-inducing peptidorhamnomannan produced by C. ulmi, the causative agent in Dutch elm disease, was subjected to additional chemical and physical characterization. Gel filtration, reductive .beta. elimination, hydrofluoric acid deglycosylation and ultracentrifugation experiments provide evidence that the wilt-inducing polymer is polydisperse with a MW range of .apprx. 105,000-120,000. The carbohydrate portion of each molecule is composed of small percentages of mannose, mannobiose, mannotriose and a tetra- or pentasaccharide composed of mannose and rhamnose plus a major component consisting of 2 or 3 long rhamnomannan chains each with a MW range of 32,000-34,000. All saccharide units are attached via O-glycosidic linkages to a protein with a MW of .apprx. 35,000. Rabbit antibodies directed against both C. ulmi and the purified peptidorhamnomannan were prepared. Their possible use in evaluating the role of the polymer in the disease is discussed.