Isolation of Spiroplasma citri from Flowers and Seeds Collected from Infected Periwinkles

Isolations were attempted from flowers, stems, and seeds from six Spiroplasma citri-infected periwinkles and from flowers and stems from two healthy plants. Each flower was separated into four parts: petals, sepals, pistils, and corolla tubes. A total of 140 seeds from infected plants were germinated, with a germination rate of 59%. Two and three months after germination, 25 plants from seeds were sampled for the isolation of S. citri. The average spiroplasma cells g-1 of diseased pistils, sepals, petals, corolla tubes, or stems was 1.87 × 108, 1.9 × 107, 1.89 × 106, 3.7 × 106, or 2.35 × 106, respectively. The number of cells isolated from pistils was significantly higher than that from stems, whereas the numbers from sepals, corolla tubes, and petals were comparable to those from stems. No spiroplasma was isolated from flower parts of two healthy plants, from seeds, or from samples collected from 25 plants grown from seeds. Results indicated that flowers were good sources for the isolation of S. citri and confirmed that there is no seed transmission of the S. citri infection in periwinkles.