Slow-growth conservation of potato microplants: efficacy of ancymidol for long-term storage in vitro

Ancymidol was investigated as an alternative medium supplement to mannitol for slow-growth conservation of potato microplants in vitro. Different conc entrations of ancymidol (0, 5, 10, 15, 20, 25, 30, 35 and 40 muM) were test ed in slow-growth media based on MS medium supplemented with either 30 or 6 0 gl(-1) sucrose. The cultures were conserved under a 16-h photoperiod at t wo temperature regimes i.e. 24 +/- 1 degreesC and 6 +/- 1 degreesC. There w ere significant interactions between ancymidol and other factors such as su crose, temperature and genotype for microplant survival, microshoot height and overall microplant growth. Ancymidol did have a beneficial effect on cu lture viability after prolonged maintenance in vitro. The growth-inhibiting effect of ancymidol persisted through a 16-month culture period. Combined effect of ancymidol, sucrose and temperature showed that optimum culture vi ability and desirable microplant growth were obtained when the cultures wer e grown in MS medium supplemented with 10 muM ancymidol plus 60 gl(-)1 sucr ose at 6 +/- 1 degreesC. Vitrification and flaccidity, which are very frequ ently observed in potato microplant cultures during prolonged maintenance i n vitro under osmotic stress (mannitol), were not observed when the micropl ants were conserved in ancymidol media. Genetic stability of potato micropl ants conserved in ancymidol media was evaluated using randomly amplified po lymorphic DNA (RAPD) fingerprints. Ancymidol did not induce any detectable genetic variation in genomic DNA as visualized by the absence of either any additional RAPD fragment or alterations in RAPD fragment patterns.