“IN VITRO” MEDIUM TERM CONSERVATION OF SOME SPONTANEOUS FRUIT TREES

The objective of our investigation is to evaluate a medium-term “in vitro” conservation protocol of some woody tree species (Prunus avium L., Prunus mahaleb L., Zizyphus jujuba Mill.). Wild relatives of cultivated fruit trees represent a source of genetic variability and can be very important in breeding programs and cultivation. For this reason, it would be of interest to use a method available for “in vitro” medium-term germplasm conservation, which involves strategies to slow plant growth through chemical and environmental manipulation of “in vitro” conditions. Effect of reduced sucrose and MS salts concentrations and combination of low temperature and light regime were examined using “in vitro” grown plant cultures. Maintenance in these conditions reduced microcuttings growth. To test the regeneration of the conserved cultures, they were transferred onto fresh culture medium. The examined species differed significantly in their survival. However they were similar in terms of proliferation ability, when they were transferred onto fresh medium. The effect of low temperature (4oC) combined with reduced light regime is the most effective method of medium term preservation for all the species. Zizyphus jujuba species resulted with highest survival rate in both used preservation methods. The optimal time of conservation without subculture on 4o C was 14 months for Z. jujube and about 6 months for P. mahaleb, and P. avium. Whereas reducing sucrose and MS salt (1/2MS) concentrations resulted optimal for 5 months for Z. jujuba, 4 months for P. mahaleb, and 3 months for P. avium.