Regeneration in vitro of economically important crop plants in the Nordic countries

Economically important crop plants comprise agronomic, horticultural and silvicultural species, of which there are numerous examples in the Nordic countries. This review only considers some species representative of the Brassicaceae, Chenopodiaceae, Poaceae and Pinaceae. By regeneration in vitro is meant the reproducible regenesis of plants from their component parts, rather than mass micropropagation which for most crop plants is as yet either irrelevant or unpractical. As regards agronomic crops, the state of application of cell and tissue culture techniques has progressed farthest with oilseed rape (Brassica napus): with allowance made for genotypic effects, regeneration from protoplasts and anther-cultured microspores has almost become routine. Again, allowing for genotypic differences, haploidization of sugar beet (Beta vulgaris) via ovule culture and regeneration of plants with the aid of disarmed, shooty-mutant plasmids of Agrobacterium tumefaciens, often without intervening tumorigenesis, has been shown to be possible. Regeneration in vitro of both Picea abies and Pinus sylvestris can be accomplished, but only when embryonic or seedling tissues are used. The problem of rejuvenation of mature tissues to allow rooting of the adventitious buds that are inducible, within limits, is still unsolved. As elsewhere, lack of understanding or control of factors such as genotype, physiological history and pretreatment of donor plants, and optimal physical (light) and chemical (medium) conditions, still hampers optimization of techniques in the Nordic countries.