VIEW ARTICLE

Establishment of an Inactive Population of Erwinia carotovora in Healthy Cucumber Fruit. J. C. Meneley, Graduate Assistant, Department of Plant Pathology, University of Arizona, Tucson 85721; M. E. Stanghellini, Associate Professor, Department of Plant Pathology, University of Arizona, Tucson 85721. Phytopathology 65:670-673. Accepted for publication 15 January 1975. DOI: 10.1094/Phyto-65-670.

A pathogenic isolate of Erwinia carotovora was injected into the centers of cucumber fruits attached to the vine without causing disease. No macroscopic or microscopic symptoms were observed during the 5- to 8- day incubation period. The bacterium, however, was reisolated from the internal tissues of the inoculated, harvested fruits. Examination of tissue from freshly pectolyzed cucumber fruit revealed that many dead and a few metabolically active cucumber cells contained motile Erwinia cells. Bacteria were microscopically observed in membrane-bound vesicles and free within the cytoplasm. Cucumber cells containing large numbers of bacteria were dead. However, some living cucumber cells, as shown by their ability to plasmolyze and accumulate neutral red into the central vacuole, contained a few motile bacterial rods. The possible significance of E. carotovora within living cucumber cells is discussed in relation to the occurrence of soft rot diseases.