The effect of individual chromosomes on in vitro morphogenic ability of immature embryos was studied using a Chinese Spring/Timstein substitution series. For this purpose 20 wheat lines of Chinese Spring with consequently substituted chromosome pairs from the cultivar Timstein together with the two parental cultivars were investigated. The regeneration ability of the studied lines was quantified by two parameters: frequency of regenerative calli and coefficient of propagation. The influence of the 5A, 1B and 4D chromosomes on in vitro morphogenesis was determined and the effect of 2A, 3A, 3B, 4B, 6B and 1D chromosomes, reported by other authors, was confirmed. The data indicated that the intervarietal substitutions of certain chromosomes caused significant variation in the number of morphogenic calli and recovered regenerants, in spite of the fact that the two parental cultivars were of similar morphogenic ability. This probably reflects the allele variation in a given locus on these chromosomes and/or background effect. The data suggest that the chromosome substitutions may have different compensatory effects depending on the similarity of the corresponding chromosomes and also on the possibilities of their expression in an alien genetic background.
Assessment of potato in vitro morphogenesis
