GENETIC-ANALYSIS OF IN-VITRO PLANT-TISSUE CULTURE RESPONSES AND REGENERATION CAPACITIES

The in vitro development of a whole plant from a single cell (eg micro spore or somatic cells) is a characteristic feature of plants. The ame nability of a plant to in vitro culture is influenced by the genotype, which is thus of major importance in the plant tissue culture respons e. The differences observed between different cultivars during in vitr o tissue culture with respect to embryogenesis and regeneration result from quantitative or qualitative genetic differences. We describe res ults obtained from quantitative genetic studies, from Mendelian geneti c analysis and from gene mapping. It is less easy to study the influen ce of cytoplasmic genomes. Moreover, it is necessary to discriminate b etween maternal effects and cytoplasmic inheritance. A conclusion from this review is that the choice of parental strains for a breeding pro gram should be realized on agronomic criteria rather than on compatibi lity with the tissue culture technique used. Fortunately, it is relati vely easy to incorporate short-term tissue culture capacity into agron omically valuable genotypes. This is of major interest since tissue cu lture remains necessary for most aspects of crop plants biotechnology. Very little is known about the molecular events that trigger in vitro embryogenesis and regeneration. It is clear that genes involved in th e tissue culture response are not specialised 'tissue culture genes'.