EXCESSIVE HOMOZYGOSITY IN DOUBLED HAPLOIDS - ADVANTAGES AND DISADVANTAGES FOR PLANT-BREEDING AND FUNDAMENTAL RESEARCH

The utility of haploids and DH lines for breeding programmes and basic research is discussed here. High effectiveness of haploid induction f rom random responding gametes and from valuable donor plants is not su fficient to ensure success in breeding. DH lines often appeared inferi or to conventionally obtained inbred lines. One of the causes may be a very high level of homozygosity, in this paper referred to as excessi ve homozygosity. Besides, colchicine treatment as well as gametoclonal and somaclonal variation could have a negative effect on the agronomi c performance of DH plants. Lack of natural selection in the first sta ges of haploid development is another important factor, negatively inf luencing haploid utility. On the other hand, there is a wide range of possibilities of using haploids as model plants for basic research. Am ong different applications, including mapping, genetic analysis, mutat ions, transformation, somatic hybridisation, biochemical and physiolog ical studies, artificial seed production and germplasm storage, the fi rst seems to be explored most effectively and give promising results.