In vitro storage and cryopreservation as substantial complements in concerted actions to better maintain and use crop germplasm.

摘要

The existence of modern cultivated plants is a result of interplaying modification by breeding and maintenance of valuable characters by storing the plant biodiversity. Genebanks were established to maintain and provide the crop diversity for use on the long term. Therefore, all possible methods for maintaining plant germplasm are necessary in order to fulfil this purpose for the various types of germplasm (field culture, seed storage, in vitro culture and cryopreservation). In vitro culture and cryopreservation are the tools with which laboratories can contribute to conservation but also to the improvement of germplasm. They are useful to protect germplasm from threats imposed by environmental hazards, pests and diseases as well as human damage. Some case studies are presented. In case of potato, a crop of high importance, 2700 accessions are maintained in vitro and about 1200 accessions are stored in liquid nitrogen through cryopreservation at the IPK Gatersleben. Also in case of banana, 1250 and 850 accessions are respectively stored in vitro and under cryopreserved conditions at the Bioversity Musa collection, Leuven, Belgium. The interrelationships between field culture, in vitro storage, and cryopreservation are determined by safety and cost factors. Most divers are the collections of Allium and of medicinal plants belonging to the family Lamiaceae, where variable sets of maintenance methods are followed in dependence on the propagation system of the material. Whereas in vitro storage and cryopreservation initially were mainly considered as tools for preservation of clonal crops, they may also contribute to outbreeding populations when they are used complementary to other methods. With the increasing use of these methods on many diverse locations, development of international collaboration becomes a focal point. This involves technology transfer between different partners, joint development of new methods and creation of networks and benefit-sharing larger storage entities. This covers also safety aspects like safety duplication of samples. The COST action 871 "Cryopreservation of crop species in Europe", having joined 21 countries, the European GenRes Project EURALLIVEG, having created a cryobank system of three countries, and the TRUST project on cryopreservation of tropical vegetatively propagated species are discussed as examples. They follow some earlier initiatives such as an EU GenRes project on Allium preservation and the European cryopreservation project CRYMCEPT. Other actions are integrative on a national level such as the CRYOVEG project, recently implemented in France. This project aims at integrating in a rational and coordinated manner cryopreservation in the overall strategies employed for conserving a range of crop species of national interest. In vitro storage and cryopreservation are not simply alternatives designed to replace other methods of conservation but rather valuable complements in an all-inclusive strategy to maintain and use plant germplasm in the long term.