Micropropagation and encapsulation: new technologies for “old” trees

It is well know that one of the advantage of the micropropagation is the very few plant tissue as initial explant to begin the in vitro procedure and that the encapsulation technology can integrate the plant material conservation. One the basis of these knowledge, in the laboratory of the in vitro culture of our Department some preliminary experiments were carried out in order to verify the safeguard possibility of monumental, historic and rural trees by these innovative technologies. So, for local and old ecotypes of (i) olive called “Cucco” (Olea europaea L.),(ii) mulberry called “Fontanarossa” (Morus alba L.) and (iii) for the monumental tree “Sequoia di Sanmmezzano” (Sequoia sempervirens Endl.) the procedure for their in vitro propagation were found by previous research. At the end of a subculture 3-4 mm-long microcuttings were excised from proliferated shoots and submitted to encapsulation made by (a) immersion in encapsulating sodium alginate solution (2.5%; w/v), (b) dipping for 30 min in complexing calcium chloride solution (1.1%; w/w) and (c) three rinses in water enriched by artificial endosperm compoesed by specific proliferation medium (half concentration and without agar) of each genotype (artificial endosperm); the encapsulating and the complexing solutions too were enriched by the artificial endosperm components. For the preliminary experiment aimed to test the effect of storage on encapsulated and naked microcuttings, the capsules were put in refrigerator at 4°C for 30, 60 and 90 days inside Petri dishes. The results showed that the viability and regrowth abilities of the encapsulated microcuttings decreased from 5 to 27% according to genotype and the olive one is the most sensitive to encapsulation. It is interesting to point out that, in general, the cold storage of the capsules permitted to recover the negative effect of the alginate matrix, at different levels according to genotype and duration of cold storage.