ИСТИНА

In natural populations of Arabidobsis thaliana, occupying northern limits of the species range (Karelia), the level of genetic diversity was evaluated using RAPD-markers (82 RAPD loci was tested). Considerable genetic diversity revealed was not typical of self-pollinating plant species. It was demonstrated that genetic differentiation among the populations was rather high, pointing to the low level of gene flow in the isolated insular populations. It was suggested that the high level of Arabidopsis population polymorphism in Karelia could be associated with extreme growing conditions at the northern limits of the species range. It is well known that class III peroxidases plays important role in plant protection against biotic and abiotic stresses. We analyzed DNA polymorphism in the AtPrx53 and AtPrx54 genes and found several alleles of studied genes in Karelian accessions. The alleles of AtPrx53 belong to one of two haplotypes, identified previously among 20 ecotypes (Kupriyanova et al., 2007). Only one accession possesses Dj-like haplotype from 6 Karelian accessions. We did not find recombinant alleles despite high level of RAPD-polymorphism in Karelian accessions and high level of recombination in peroxidase genes AtPrx53/54 (Kupriyanova et al., 2010). The total number of all studied by us AtPrx53 alleles is 26. Among them 17 belong to Col and 10 belong to Dj-like haplotypes (including TSU-1 allele submitted to TAIR by D.Weigel). Two of the amino acid substitutions (Phe/Ser180 and Asp/Asn270) responsible for the difference in electrophoretic mobility of AtPrx53 allozymes from Karelia accessions as in other ecotypes. The revealed pattern of polymorphism at the AtPrx53 and the strong haplotype structure in the absence of detectable recombination across AtPrx53 may be interpreted as evidence of balancing selection on this locus or other nearby sites.