ENCAPSULATION: PROMISING TECHNOLOGY FOR NURSERIES AND PLANT TISSUE LABORATORIES

Abstract

The concept of encapsulation was firstly announced in 1978 by Murashige who assumed the use of this technology to protect “vitro-derived” somatic embryos during transport and manipulation in nurseries and farms, limiting the synthetic seed manufacture to the exclusive use of somatic embryos. At this moment, after more than 30 years of intensive research, the concept of encapsulation permits to consider that any meristematic plant tissue (obtained in vivo or in vitro) can be enclosed in a protective and nutritive matrix as long as it maintains the ability to convert into a plantlet under in vitro or in vivo environmental conditions (synthetic seed) or to evolve in shoots in a laboratory of micropropagation (capsula), also after transport and/or storage. Usually, the encapsulation procedure adopted to obtain synthetic seed or capsula includes three steps: coating, complexation and rinsing. After these steps, plant tissue portions of 3-4 mm result, enclosed in a gelling matrix which assures protection from dehydration and mechanical damages. When unipolar plant explants, as buds or microcuttings, were employed to produce synthetic seed, inductive treatment has to be applied in order to induce root emission after sowing, especially when in the encapsulation plant tissues of species with low rooting potential were involved. These treatments increase the steps to produce synthetic seed, making a large scale diffusion of the technology economically difficult for some agricultural crops. From this point of view, intense research is in progress in some laboratories, in order to look for mechanical and/or automation application, especially in the steps that require intensive manual labor. Although the encapsulation technology at the moment presents some open questions that have to be solved, interesting perspectives for its future commercial use are open because the two products of this innovative technology (capsula and synthetic seed) are useful for: the effective channel for diffusion of new plant genotypes; direct sowing of synthetic in field, greenhouse or growth chamber; plant material storage; biodiversity conservation; exchange of in vitro plant material between laboratories and nurseries in different countries.