Arabidopsis thaliana as an Experimental Host of the Mollicute Spiroplasma citri. Jacqueline Fletcher, Department of Plant Pathology, Oklahoma State University, Stillwater. Catherine E. Eastman, Center for Economic Entomology, Illinois Natural History Survey, Champaign. Plant Dis. 76:862-864. Accepted for publication 23 March 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0862.

Beet leafhoppers (Circulifer tenellus) that had been confined on Spiroplasma citri BR3-infected turnip plants were caged with seedlings of Arabidopsis thaliana (ecotypes Lansburg Erecta, Columbia, and Niedersans) for 4–7 days. Symptoms of S. citri infection in Arabidopsis included stunting of the basal rosette, curled and deformed cauline leaves, floral stunting and necrosis, reduced silique size and seed set, and reduced internode length on the floral stalk with terminal bunching of flowers and siliques. Infection of test plants occurred with as few as one leafhopper per plant. Spiroplasmas were cultured from 34 of 42 exposed plants, and the protein profiles of reisolated spiroplasmas in polyacrylamide gels were indistinguishable from those of cultured S. citri BR3. S. citri was also detected in infected Arabidopsis samples by ELISA. These findings extend the potential of Arabidopsis as a host plant for genetic studies of host-pathogen interactions.