Feral populations of Brassica oleracea along Atlantic coasts in western Europe

• Published in: Ecology and evolution Vol. 10; no. 20; pp. 11810 - 11825
• Main Authors: Mittell, Elizabeth A., Cobbold, Christina A., Ijaz, Umer Zeeshan, Kilbride, Elizabeth A., Moore, Karen A., Mable, Barbara K.
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.10.2020; John Wiley and Sons Inc; Wiley
• Subjects: Brassica; Brassica oleracea; Climate change; Climatic conditions; Coasts; Crop resilience; crop wild relatives; Crops; Cultivars; Deoxyribonucleic acid; DNA; DNA sequencing; Domestication; environment–genotype associations; Feral populations; Genetic diversity; Genomes; Genotypes; Hypotheses; isolation by distance; Morphology; Original Research; Plant breeding; Population; Population genetics; Population structure; Populations; Seeds; Soil chemistry; Soil pH; Wild type; United Kingdom > UK; France; Europe; Spain; Western Europe; isolation by distance; Brassica oleracea; feral populations; crop wild relatives; environment–genotype associations; domestication
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.6821

There has been growing emphasis on the role that crop wild relatives might play in supporting highly selected agriculturally valuable species in the face of climate change. In species that were domesticated many thousands of years ago, distinguishing wild populations from escaped feral forms can be challenging, but reintroducing variation from either source could supplement current cultivated forms. For economically important cabbages (Brassicaceae: Brassica oleracea), “wild” populations occur throughout Europe but little is known about their genetic variation or potential as resources for breeding more resilient crop varieties. The main aim of this study was to characterize the population structure of geographically isolated wild cabbage populations along the coasts of the UK and Spain, including the Atlantic range edges. Double‐digest restriction‐site‐associated DNA sequencing was used to sample individual cabbage genomes, assess the similarity of plants from 20 populations, and explore environment–genotype associations across varying climatic conditions. Interestingly, there were no indications of isolation by distance; several geographically close populations were genetically more distinct from each other than to distant populations. Furthermore, several distant populations shared genetic ancestry, which could indicate that they were established by escapees of similar source cultivars. However, there were signals of local adaptation to different environments, including a possible relationship between genetic diversity and soil pH. Overall, these results highlight wild cabbages in the Atlantic region as an important genetic resource worthy of further research into their relationship with existing crop varieties. We investigated the population structure of cabbage (Brassica oleracea) populations found around the coasts of the UK and the north coast of Spain, including many populations at the edges of the B. oleracea range that have not been seen in the literature before. This study system is particularly interesting because existing evidence suggests that domesticated plants escaped from gardens and fields, and established these wild populations relatively recently across a large environmental gradient. We suggest that these wild cabbage populations hold agriculturally useful genetic resources for an economically important plant genus.