Dog babesiosis is a severe disease with symptoms of hemolitic anemia. The etiological factor of this disease are protozoa organisms from the family Babesidae. Molecular biology techniques indicate that the genetic structure of these parasites is extremely diversified. On the basis of the analysis of Babesia DNA, new variants of the protozoa were detected. It is possible that these new variants of Babesia are characterized by high virulence for dogs and high resistance to drugs used in babesiosis therapy.
Results of research carried out within 1995-1998 on application of molecular methods to identify the fungal pathogens of cereals were reviewed in the paper. Results of studies on fungal genome of Fusarium species - the number and size of chromosomes were presented. Available information concerning the possibilities of fungal pathogens identification with the use of RFLP, RAPD-PCR, SCAR and AFLP methods, based on the analysis of extracted fungal DNA and PCR (polymerase chain reaction) procedure were described.
The paper presents two examples of population, where preserving the genetic variability plays very important role. One of those population is European bison - endangered species which passed serious bottleneck. The second is Japanese quail herd bred as closed population for many generation. Based on those examples the practical aspects of breeding strategy were discussed. As a results of breeding strategy the level of inbreeding was presented as well as the rate of its increasing. The European bison population is divided into two genetic lines and the level of inbreeding is equal to 54% within Lowland line and is lower (ca 30%) within Lowland-Caucasian line. Such high level is a consequence of small numbers of founders. The mating system used in two Japanese quail lines allowed to keep the rate of inbreeding below 1% per generation.
In modern protection systems of cultivated plants the genetical resistance may play an important role as an environment - friendly method for discase control. To achieve this goal genetical resistance of plants should be diversified in time and space as far as modern cultivation systems allow. In the paper the following ways of more efficient use of genetical diversity for disease restriction are discussed: - the use of disease resistant cultivars, - mixed cropping (intra - and interspecies mixtures), - integrated control.
Genome analyses in model species have provided value in biological research. As it has become clear that coding gene sequences are well conserved among genera and even tribes, comparative mapping makes it possible to transfer the information on chromosome structure and gene organization from species with well-developed genetic maps to species where such information is scarce. Furthermore, genome comparisons on the basis of a well characterized model genome in relation to more complex genomes in crop plants, offer new information about the mechanisms responsible for the evolution of chromosomal structure. Among dicotyledonous plants, A. thaliana plays the role of a model plant, especially for closely related crop species of the genus Brassica (cruciferous oilseeds and a variety of leafy vegetables). The A. thaliana genome project provides an opportunity of systematic and large-scale identification and isolation of Brassica genes, and to a better understanding various aspects of the Brassica biology and, eventually, of its breeding problems. This aspects is demonstrated on an example of the A. thaliana gene families coding for ACC syntases and oxidases, key enzymes in ethylene biosynthesis. Further progress in the analysis of A. thaliana and rice genomes should establish the synteny with many related crop species by means of detailed comparative mapping. This may greatly facilitate gene identification and studies on their organization within the genome.
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