The use of ITS markers for identification of birch species from section Apterocaryon

Abstract

Betula nana, B. humilis are shrub birch forms of the section Apterocaryon (dwarf birches), widespread in the Northern Hemisphere. The species are found on marsh, tundra and bald soils, often growing together on sphagnum bogs. There were suggestions about the hybridization of the diploid B. nana and B. humilis with the tetraploid downy birch B. pubescens from the section Betula (white birches). Attempts were made to study the presence and intensity of hybridization of these species using molecular genetic methods. The aim of the study is to investigate the genetic polymorphism of B. nana and B. humilis in the Middle Urals based on ITS markers of nuclear ribosomal DNA. These markers are for the first time studied in shrub birch forms on the Russian Federation territory. It is shown that the ITS 1-2 region is informative and makes it possible to differentiate closely related birch species B. humilis, B. nana growing in the Middle Urals. Species were characterized by individual ribotypes; B. nana samples had 5 ribotypes, and B. humilis samples had 2 ribotypes. Populations of B. nana showed greater variability in this region compared to B. humilis, which may indicate a higher adaptive potential of dwarf birch, as well as the absence of significant changes in the population size of this species during the last Quaternary glaciation.