Genetic polymorphism of populations and phylogeny of the Central Siberian Polygonum (Polygonaceae) section using ISSR and chloroplast markers

Abstract

This article is devoted to the study of genetic polymorphism of populations and phylogeny of Polygonum section using ISSR and chloroplast markers. Section Polygonum is a taxonomically complex group. Identification of individuals is complicated because of the small size of plants, the processes of interspecific hybridization, heterocarpy, phenological and ecological plasticity. In this work, the genetic variability of six populations of five knotweed species growing in Krasnoyarsk was studied. ISSR analysis revealed that the level of genetic diversity in the populations varies from 4.17 % to 35.83 % and has maximum values for genetically close species P. sabulosum (P = 35.83 %) and P. arenastrum (P = 22.5–30 %). Minimum values of genetic diversity were observed for populations of P. aviculare (P = 4.17 %) and P. calcatum (P = 5 %). The studied populations are characterized by a very high level of genetic differentiation (Gst = 0.78) and reliably belong to different species. On the similarity dendrogram (UPGMA), individuals of these species form clearly distinct clades. The genetic structure of populations using STRUCTURE also shows a reliable division of individuals into 5 clusters corresponding to the studied species. Phylogenetic analysis using the trnL-trnF chloroplast region shows the presence of a 5-nucleotide deletion and two transversions that makes it possible to divide the studied group of Polygonum into two morphologically different clusters. The first group is formed by P. arenastrum, P. calcatum, P. caspicum, P. sabulosum and characterized by the absence of a main shoot, a gradual reduction of leaves to the top of shoots and the perianth dissection by 1/2 of its length. The second group includes P. aviculare, P. boreale, P. neglectum, P rectum that have a main shoot, heterophilly, perianth dissection by 2/3–3/4 of its length. Two substitutions have been identified in the matK sequences, however it is less informative for solving taxonomic issues of the studied group.