Molecular comparisons of Salsola tragus from California and Ukraine

Abstract

In California, the exotic invasive plant Salsola tragus L. (Russian thistle) has been found to consist of two genetic entities, types A and B. Type A, with chromosome number 2n = 36, was identified as S. tragus s.str., but type B, with 2n = 18, was not identical with Salsola species found elsewhere in the world. Plants of S. tragus from Ukraine were subjected to isoenzymic and DNA analyses to determine whether type B was found there and to compare S. tragus from Ukraine with that in California. In isoenzymic assays, plants from Ukraine exhibited patterns of aspartate aminotransferase and 6-phosphogluconate dehydrogenase activity after non-denaturing electrophoresis that were identical with those for S. tragus from California. No Ukrainian accessions had an isoenzymic pattern that resembled type B from California. DNA-based assays, using random amplified polymorphic DNA and inter-simple sequence repeat primers, indicated that all the Ukrainian accessions were similar to S. tragus type A from California and not to Californian type B. The area of origin of type B remains unknown, although it has recently been found to be widespread in southern Africa, where it is also believed to be an introduced species.