ISHS Acta Horticulturae 377: VIII International Symposium on Virus Diseases of Ornamental Plants
EXPRESSION OF POTATO SPINDLE TUBER VIROID (PSTVD) IN CHRYSANTHEMUM CV. SNOWDON TRANSFORMED WITH PSTVD CDNAS. |
| Authors: | L. Trnená, J. Matoušek, S. Rakousky |
| Abstract:
Chrysanthemum cv. Snowdon was transformed with two different expression vectors containing tandem dimers of PSTVd cDNA in plus orientation. No PSTVd appeared in plants transformed with pCB1413, otherwise strongly infectious PSTVd (severe) construct (Matoušek et al., 1989). PSTVd infection was detectable in chrysanthemum transformed with cDNA of PSTVd lethal (KF440-2) inserted into the vector pKYLXT7 (Schardl et al., 1987). True replication of PSTVd in chrysanthemum was proved by the fact that PSTVd circular forms were detectable using bidirectional PAGE (Matoušek, Schubert, 1988). No changes in the PSTVd (lethal) sequence propagated in chrysanthemum were found using PAGE of heteroduplexes under native conditions (Zimmat et al., 1990). Amount of PSTVd in transformed chrysanthemum leaves was compared using dot blot hybridization with amount of PSTVd in tobacco leaves transformed with the same vector pKYLX7. PSTVd propagation in tobacco was found to be blocked in some extent due to inhibition of some transportation step(s) (unpublished). Despite of that, twelve times higher concentration of viroid RNA was found in transformed tobacco than in transformed chrysanthemum and was 6.4±2.48 and 0.5±0.36 pg/mg fresh mass for tobacco and chrysanthemum, respectively. Although some cultivars of chrysanthemum were described to be the hosts for PSTVd (Niblett et al., 1980) our results are indicative of total inhibition of propagation of PSTVd severe in cv. Snowdon. PSTVd lethal strain replicated with very low intensity in this cultivar, suggesting that for the infection, the viroid RNA structures formed probably by different PSTVd strains in vivo are the most important. | |
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