VIEW ARTICLE

Effects of Elevated Temperature on the Ultrastructure of Mycoplasmalike Organisms in Periwinkle. A. Zelcer, Virus Laboratory, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel; G. Loebenstein(2), and M. Bar-Joseph(3). (2)(3)Virus Laboratory, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. Phytopathology 62:1453-1457. Accepted for publication 3 July 1972. DOI: 10.1094/Phyto-62-1453.

The ultrastructure of mycoplasmalike organisms (MLO) in safflower phyllody-affected periwinkle plants (Vinca rosea) kept at 40 C was compared with that in control plants grown at 25 C. MLO in control plants resemble other plant MLO. Small spherical bodies originating by budding from large MLO were observed, as well as numerous free ones, both in sieve cells and within sieve pores. Gradual degradation and disappearance of normal components within the MLO were observed when periwinkle plants were kept at 40 C. Electron-dense material accumulated in clumps near the membrane, and the contents began to disappear after 1 day. No additional changes were observed after 7 days (and up to 50 days) at 40 C, when MLO seem to be almost devoid of ribosomes and other components.