In vitro storage of plum germplasm by slow growth

In this study, in vitro slow growth storage was investigated in four cultivars of two Sicilian (Southern Italy) plum species (Prunus domestica L. and Prunus cerasifera Ehrh.-two genotypes each). Established shoot cultures were preserved at 4°C in the dark in a Murashige and Skoog basal medium containing one of two different concentrations of sucrose (20 and 30 g/l) and with or without growth regulators. We tested the effects of cold storage, genotype and media on survival and re-growth capacity of explants after 3, 6, 9 and 12 months of storage. Effective minimal growth under cold conditions occurred in all four genotypes. The media composition did not affect survival, which, instead, appeared to be genotype-dependent. P. domestica genotypes survived cold storage the longest, for 12 and 9 months; instead, P. cerasifera ones remained viable for up to 6 months. All genotypes retained proliferation capacity under standard conditions and their re-growth capacity seems to be strongly genotype-dependent, closely related to their individual performance in response to the experimental condition of storage.