Disease Note.

Mycoplasmalike Organisms Associated with Vicia ervilia . S. Castro, Departamento de Proteccion Vegetal, CIT-INIA, Apartado 8.III, 28080 Madrid, Spain. M. Saiz, and J. Romero, Departamento de Proteccion Vegetal, CIT-INIA, Apartado 8.III, 28080 Madrid, Spain. Plant Dis. 78:101. Accepted for publication 24 August 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0101B.

Bitter vetch (Vicia ervilia (V.) Willd.) is a legume used as an important source of forage in dry regions of Mediterranean countries. A disease characterized by severe stunting, leaf curling, and general yellowing was observed in bitter vetch plants growing naturally in central regions of Spain. Plants showing these symptoms were collected in order to delect and characterize the causal agent of the "yellows disease." Selected parts of these plants were grafted to periwinkle plants (Catharanthus roseus (L.) G. Don). Some of these showed yellowing and floral dwarfism. When sections of both diseased bitter vetch and grafted periwinkle plants were analyzed by the DAPI fluorescence test (1) and Dienes's stain (2), intense fluorescence and blue-stained areas, respectively, were observed in the phloem sieve tubes but not in asymptomatic tissue. Electron microscopy of ultrathin sections from the same material revealed the presence of pleomorphic wall-less microorganisms in the sieve elements, surrounded by a three-layered unit membrane. These were never observed in healthy plant sections. These results suggest a mycoplasmalike organism as the cause of the disease. This is the first report of a Mollicute infecting legumes in Spain