Genetic Diversity of Four Species of the Genus Astragalus L. Section Cenantrum Bunge (Fabaceae) in the Asian Part of Russia according to the Data of trnL–trnF Chloroplast DNA Variability and Isozyme Markers

The genetic diversity and phylogenetic relationships of four species of the genus Astragalus of the section Cenantrum, A. frigidus, A. mongholicus, A. penduliflorus, and A. sericeocanus from the Asian part of Russia, were studied according to the variability of trnL-trnF cpDNA and isozyme markers. For each species, specific sets of chloroplast haplotypes, alleles, and isoenzyme frequencies were identified. According to cpDNA data, the studied populations are characterized by low haplotype (h varies from 0.095 to 0.333) and nucleotide (π varies from 0.00019 to 0.00378) diversity. Most of the populations (20 out of 27) were monomorphic. According to the data of isoenzyme analysis, the indicators of polymorphism for three species (with the exception of the monomorphic population of A. penduliflorus) have rather high values. For a species on average, the polymorphism (P95) varies from 55.5 to 85.5%, the number of alleles per locus (A) is from 1.8 to 2.7, and the observed heterozygosity (Ho) is from 0.134 to 0.215. The geographic confinement of haplotypes and polymorphic populations of A. frigidus and A. mongholicus was revealed in Altai and Baikal Siberia. These localities are probably situated at the intersection of migration routes or refugia.