Cel The objective of this concerted action was to coordinate research on molecular mechanisms of genetic instability in plant tissue culture and regeneration and to concentrate European efforts into an integrated approach which combines the expertise, materials and facilities from the different participating groups. Somaclonal variation is an important problem in genetic manipulation of crop plants and in the micropropagation of ornamental and horticultural plant species where it results in unwanted variations in regenerated plants and losses in fertility. Some of the changes which arise can be useful for plant breeding, for mutant isolation (when used in conjunction with in vitro selection), or as a means of achieving introgession asexually in hybrids. However, these applications are currently limited by the unpredictable and uncontrolled way in which the variations arise. From both the viewpoint of removing unwanted variation and generating useful variations, it is essential that somaclonal variation is controlled. The main objective is to determine the underlying mechanisms and to identify a coordinated research effort directed towards this goal.Tissue culture-induced variation considerably affects the efficiency of transformation and subsequent expression of transformed genes. Changes can be detected in single isolated cells using polymerase chain reaction (PCR) and random amplification of polymorphic deoxyribonucleic acid (RAPD) technology. The stability of the wheat genome in cell suspension and protoplasts depends upon its composition. Nuclear genes control changes in the mitochondrial genome during somatic embryogenesis and major genes on chromosomes 1AL, 3AL, 3BL, and 3DL control embryo induction in somatic cultures. Changes in copy number of repeated sequences occur in response to biotic and abiotic stress. In rice, amplification of the genome is a massive phenomenon and this includes sequences in the chloroplast genome. Sister chromatid exchanges can be used as a measure of genetic change in vivo and in vitro.Research on genetic instability in tissue culture provides clear evidence of the extreme plasticity of the plant genome under stress and has implications for obtaining efficient transformation and for our understanding of the generation of genetic divers ity. Tissue culture provides an experimental system evolutionary processes in action.Uncontrolled instability can arise through the culture of plant cells and their regeneration into whole plants. Although a well described phenomenon, it's causes are not yet known. Factors that affect the frequency of changes include in vitro culture conditions, tissue source, ploidy and genotype indicating that whilst variation is influenced by culture conditions, it originates both from the differentiated donor tissue and from the that different genomes respond to the stress of culture. Some genomes are more unstable irrespective of ploidy, suggesting that genome composition is important. Evidence indicates that repetitive sequences have an important role in changes induced in both coding and non-coding regions of the genome. This proposal is a concerted approach to determine the molecular basis of genetic instability in plant regeneration through interrelating studies on: the stability of endogenous and transformed genes; the behaviour of sequences in euchromatin compared with heterochromatin; amplification of coding and non-coding sequences; changes in mitochondrial DNA that occur during somatic embryogenesis; aberrations in cell division. Instability will be studied in relation to states of differentiation, somatic embryogenesis compared with organogenesis, in vitro culture conditions and changes in selective constraints imposed during cell division and morphogenesis. An understanding of how the genome responds in relation with in vitro culture conditions will provide the vital logic necessary for control over instability in plant regeneration. Fundamental knowledge on how plant genomes change and of the constraints imposed during differentiation and morphogenesis will also be gained. Dziedzina nauki natural sciencesbiological sciencesgeneticsDNAnatural sciencesbiological sciencesevolutionary biologynatural sciencesbiological sciencesdevelopmental biologynatural sciencesbiological sciencesgeneticschromosomesnatural sciencesbiological sciencesgeneticsgenomes Program(-y) FP2-BRIDGE - Specific research and technological development programme (EEC) in the field of biotechnology (BRIDGE), 1990-1994 Temat(-y) Data not available Zaproszenie do składania wniosków Data not available System finansowania Data not available Koordynator Institute of Arable Crops Research Wkład UE Brak danych Adres Long Ashton Research Station BS18 9AF Bristol Zjednoczone Królestwo Zobacz na mapie Koszt całkowity Brak danych
