Brassica oleracea and its wild allies. Diversity and in situ conservation. – Botanica Lithuanica, Suppl. 2: 53–59
The Brassica oleracea cytodeme, with the chromosome number 2n = 18, consists on one hand of horticultural crop plant, as a result of domestication of B. oleracea in particular, and on the other hand of numerous wild species. The wild, perennial species inhabit maritime habitats, mostly coastal limestone cliffs and rocky islets, and occur as vicarious species in the Mediterranean region and along Atlantic coasts. Diversity within and between species has been studied with molecular methods in particular. Analysis of gene diversity values indicate a considerable within population variation regardless of population size. However, the level of homozygosity tends to be higher in smaller populations. Even adjacent populations, which are geographically separated by a few kilometres only, show quite different isozyme patterns indicating that gene flow between populations is highly restricted. RFLP analysis showed that the ten wild species tended to cluster into four groups according to their geographic regions. Crossing experiments lead to the conclusion that all cultivated forms including the Chinese B. alboglabra and the wild species belong to the same cytodeme. Sicily is considered to be an important centre of diversity of wild Brassica species, but actual or potential threats have been recognised in at least half of the Sicilian populations. Due to the present situation a plant for dynamic in situ conservation of the Sicilian species is proposed.
Keywords: Brassica oleracea, in situ conservation.