ANALYSIS OF THE TAXONOMIC STATUS OF LIMONIUM CASPIUM (WILLD.) P. FOURN. USING THE ITS1-5.8S-ITS2 REGION

Abstract

There are 15 representatives of the genus Limonium Mill in Ukraine. The taxonomic status of some of them requires clarification. In particular, some taxonomists consider L. caspium (Willd.) P. Fourn. to be a separate species, while others tend to consider this name as a synonym for L. bellidifolium Dumort. Until now, only one sample of L. caspium from eastern Iran has been analyzed using molecular genetic approaches: for this accession, the ITS1-5.8S-ITS2 of 35S rDNA region was sequenced. For both species, L. caspium and L. bellidifolium, samples from the territory of Ukraine have not yet been examined using molecular taxonomy methods. In this work, we amplified and sequenced ITS1-5.8S-ITS2 region for two L. caspium and two L. bellidifolium samples from southern Ukraine. All four samples appeared to be identical in this region. They also do not differ from previously sequenced samples of L. bellidifolium from France, Turkey and Greece. On the other hand, the sequence of L. caspium from Iran has five nucleotide substitu-tions and four indels compared to the mentioned samples. The phylogenetic analysis revealed that representatives of the so-called "L. bellidifolium complex", which, in addition to the two species mentioned, also includes L. iconium and L. tamaricoides analyzed in this work, are grouped together with representatives of the Nephrophyllum section. A similar result was obtained in the studies of other authors using the ITS1-5.8S-ITS2 sequence and regions of chloro-plast DNA. However, according to the IGS 5S rDNA sequence, representatives of the "L. bellidifolium complex" in our previous work were grouped together with the species of the Limonium section, to which they were previously as-signed based on morphological characters. Such a discrepancy between phylogenies using different genomic regions indicates the reticular nature of the evolution of the genomes of representatives of this group and indicates probable hybridization events in their past. Within the clade of the "L. bellidifolium complex" that we obtained in our analysis, the sample of L. caspium from Iran forms a sister branch to all its other representatives. Thus, the comparison of the ITS1-5.8S-ITS2 region shows that the Ukrainian samples identified as L. caspium do not differ from L. bellidifolium. However, to finally clarify the taxonomic status of L. caspium, it is necessary to analyze more samples from different geographic origins.