Open access publications in the SLU publication database

Abstract

Various theories exist about the progenitors of B. oleracea L. (cole crops) and the area of its domestication. Relatively recent molecular data have pointed at the wild species growing on the European Atlantic cliffs as the closest relatives to all the cultivated types.

Compatibly with all the existing observations, an alternative hypothesis is formulated here, namely that the domestication of B. oleracea occurred in a Mediterranean location, while the crop reached the Atlantic coast only at a later date, with the movement of people and cultures. The wild Atlantic populations are supposed to be re-naturalized escapes from the fields. If this theory could be confirmed, it would be plausible for all the cole crops to show the highest affinity with the Atlantic populations, since these belonged to the same genetic pool that underwent a domestication bottleneck.

Our experimental work revolved around attempts to test the above-mentioned hypothesis through indirect means. Linguistic, literary and historical aspects of the use of cole crops indicate a deep-rooted knowledge and use of cole crops as well as of their wild relatives by the ancient Greek and Roman civilizations. Moreover, words used to name the coles throughout Europe largely if not exclusively derive from Greek or Latin roots. Analysis of the genetic diversity of leafy kales from around Europe did not find a geographic pattern and a directionality. Agro-ecosystems mimicking a situation of
initial domestication, with cole crops and one of their wild relatives (B. rupestris Raf.) growing in close proximity to one another were analysed. Patterns of gene flow have been identified and domestication scenarios have been described.

Evidence of populations of coles escaping from the field and becoming indistinguishable from truly wild populations was obtained with molecular marker studies. Finally, attention was given to the legal aspects of collecting wild specimens of genetic resources in Europe, with an analysis and discussion about this issue.

This work analyses strengths and weaknesses of the existing theories of domestication of B. oleracea and supports an alternative and original hypothesis that will deserve to be further tested in future before a conclusive statement can be made on the origin of the coles.