Conservation of Hardwood Forest Species

Abstract

Conservation of forest genetic resources is essential for meeting the demand for future wood products. Genotypes with improved characteristics are nowadays widely produced through conventional breeding programmes, by selection of mature superior trees, by genetic transformation procedures, etc., which are important for increasing the productivity of forestry clonal plantations. Strategies for forest biodiversity conservation today are well defined, among which cryopreservation is viewed as a complementary storage method, important for plant tissues with specific characteristics (vegetatively propagated species). In addition, many hardwood forest trees produce recalcitrant seeds (seeds that cannot be stored for long periods under conventional conditions) that only would be stored on a long-term basis through cryopreservation. The availability of simple, reliable and cost-effective strategies for conservation of hardwood forest species (with special attention to recalcitrant species of the Fagaceae family) will be highlighted in this review. Specifically, emphasis will be addressed to the following topics: (i) medium-term conservation through slow growth storage; (ii) cryopreservation techniques; (iii) selection of explants for cryopreservation: in vivo collection of embryonic axes and dormant buds and in vitro collection of shoot tips and embryogenic cultures; and (iv) genetic stability of cryopreserved material. The limited application of cryopreservation to the development of large cryobanks of hardwood forest species also will be mentioned.