Cochlearia

Abstract: Chloroplast DNA restriction-site variation was analyzed in 30 accessions representing 20 species from the major lineages in Thlaspi s.l. (previously described as genera by Meyer 1973, 1979) and allied genera from the subtribe Thlaspidinae (Peltaria, Teesdalia, Cochlearia, Ionopsidium, Aethionema). A total of 161 variable restriction sites were detected. Phylogenetic analyses indicated a division of Thlaspi s.l. into three groups consistent with Meyer's genera Thlaspi s. str., Microthlaspi and Noccaea/Raparia. The genus Thlaspi s.l. as currently described proved to be paraphyletic because one of its major lineages, i.e. Thlaspi s. str., appeared to be more closely related to other genera (Peltaria, Teesdalia) than to the remaining lineages of Thlaspi s.l., i.e. Noccaea/Raparia and Microthlaspi. Sequence divergence values (100 x p) between the Thlaspi s.l. lineages were similar to values between these groups and related genera (Teesdalia, Peltaria), respectively. Chloroplast DNA variation was also used to assess subtribal classification of the genera studied. The cpDNA data were inconsistent with the controversial taxonomic classifications based on morphology. The molecular data would suggest that (1) the subtribe Thlaspidinae, as traditionally described, is not monophyletic; (2) the Thlaspidinae should be reduced to a group consisting of Thlaspi s. str., Peltaria, Teesdalia, Microthlaspi, Noccaea/Raparia, and that Aethionema should be excluded from the Thlaspidinae; and (3) Cochlearia and Ionopsidium represent the subtribe Cochleariinae.

Abstract: : Within the genus Cochlearia L. sect. Cochlearia three isozyme systems (aspartate aminotransferase, leucine aminopeptidase and phosphoglucomutase) have been analysed at the populational level for eleven species with different ploidy levels. Nine loci complexes were resolved with a total of 33 alleles from 89 populations. In general, polyploids displayed higher numbers of alleles per species and per population. A notable exception is diploid C. pyrenaica with as many alleles as some polyploids. Data support: (1) the origin of tetraploid C. officinalis from C. pyrenaica s.l., particularly from C. aestuaria; (2) the allopolyploid origin of octoploid C. anglica from C. officinalis; (3) the allopolyploid origin of hexaploid inland taxa C. polonica, C. tatrae and C. bavarica via hybridization between C. pyrenaica and C. officinalis; (4) a putative allopolyploid origin of hexaploid coastal species C. danica by hybridization between C. pyrenaica s.l. and C. officinalis accompanied by a shift in chromosome complement. A scenario summarizing our present understanding of the evolution within Cochlearia sect. Cochlearia is presented.

Abstract: Chloroplast DNA (cpDNA) restriction site variation (RFLP), has been analysed in the genus Cochlearia L. sections Cochlearia O.E. Schulz and Glaucocochlearia O.E. Schulz. Members of section Glaucocochlearia are clearly separated from those of section Cochlearia by 28 site mutations, thus supporting taxonomic arrangements into the two sections mentioned. RAPD studies provide further strong evidence for closer relationships among tax a within each section than between sections. CpDNA sequence divergence values in section Cochlearia are extremely low. Although 91 accessions representing 11 species have been analysed by 25 restriction enzymes, only four restriction site mutations were detected characterising six different cp genome types. Low levels of chloroplast DNA divergence would suggest that taxa of section Cochlearia are closely related and most likely have diversified recently. Polyploid Cochlearia offcinalis (2n=24), C. anglica (2n=48) and C. danica (2n=42) displayed infraspecific variation for cp genomes, which could be partly explained by multiple origin and by reticulate evolution. RAPD analyses (22 primers, 140 informative characters, ten taxa from 17 accessions) do not only strongly support these arguments but also helped to clarify speciation processes and biogeographic aspects in more detail. It is argued that South West Europe was the primary center of origin of the polyploids, second centers may be the British Isles, Iceland and locally restricted parts of Middle Europe.