M.G. Bellardi, A. Bertaccini
An electron microscopy study of gloxinia (Sinningia speciosa Lodd.) plants showing virescent flowers, deformed and smaller green buds and chlorotic - reddish spots on the leaves, has been carried out in Italy. In leaf crude sap such as in ultrathin sections of leaf and flower tissue, a virus similar to tomato spotted wilt virus (TSWV) was found. The particles, ranging from 50 to 70 nm in size, bounded by a double layered membrane were observed only in the cytoplasm. In the leaf tissue, clusters of virus were present close to the cell wall; in the flower tissue the particles were solitary and scattered throughout the cytoplasm.

Spheroid and/or elongated bodies, ranging from 100 to 800 nm, were also found in the cells of floem and xylem parenchyma and in mature or immature cells of sieve tubes. These bodies were bounded by a double membrane and seemed to contain internal structures similar to ribosomes and DNA fibrils. The ones located in the sieve tubes were similar to mycoplasma-like organisms (MLO); those present in the parenchymatic cells have not been identified yet.

Bellardi, M.G. and Bertaccini, A. (1990). ELECTRON MICROSCOPY OF VIRESCENT GLOXINIA PLANTS. Acta Hortic. 266, 509-516
DOI: 10.17660/ActaHortic.1990.266.68

Acta Horticulturae