“Determining the DNA order of the material, in our collections and others, enables science to trace the traits hidden until now, in thousands of varieties and wild populations of lettuce and other crops. It also shows how important the preservation and protection of biodiversity and genetic sources are for a sustainable food supply in times of climate change and a growing global population.
The Key to a Wealth of Genetic Material for BreedingĪccording to Rob van Treuren and Theo van Hintum, the two Wageningen co-authors of the publication, the research beautifully demonstrates how much information can be collected from DNA information in a genebank collection. It also appears that determining the location of several genes in the DNA is possible by analysing the relationship between DNA variation and traits through so-called Genome Wide Association Studies (GWAS). The study was also able to determine the point at which the more recent iceberg lettuce diverged from “ancient” butterhead lettuce in the genetic material of the wild Lactuca virosa, a fact that had long been suspected based on the genealogical data of these lettuce varieties.Īnalysis of the relationship between the DNA information and traits of the cultivated lettuces shows that rigorous selection took place for traits that were desirable for production and consumption, the “domestication traits” like the absence of spines and thorns, which resulted in reduced diversity in the regions of the DNA where the genes for these traits are located. Iceberg Lettuce Versus “Ancient” Butterhead Lettuce The slow migration of lettuce throughout Europe via the Roman Empire, as well as the transition from seed crop to leaf crop, can also be reconstructed. As it turns out, the modern varieties of cultivated lettuces mostly resemble their wild predecessor Lactuca serriola from the Caucasus and the first cultivated lettuces must have been grown for seed and used for oil. It appears that a wealth of information became available. The results from the first 445 types of lettuce have led to a publication in Nature Genetics about the origins and breeding history of the crop. In collaboration with the Chinese BGI, the DNA order is being determined for all 2500 types, including an analysis of genetic variants and the differences and similarities between these variants. This is the largest, most complete, and best documented lettuce collection in the world. The Centre for Genetic Resources, the Netherlands (CGN), which is the Dutch gene bank and part of Wageningen University & Research (WUR), manages this collection of 2500 lettuce types. We’ve learned all that information from the DNA in these lettuce types!ĭifferent types of lettuce around the world And the story told by the DNA continues, up to the Americans that needed properties from wild varieties to change soft, smooth butter lettuce into hard, puckered iceberg lettuce. These first lettuces were only suitable for harvesting seeds to extract oil, and the ancient Greek and Romans further bred these plants (at that time, they still had thorns on the leaves) to be used as leafy vegetables. The first wild plants were modified for cultivation 6000 years ago in the Caucasus. Then try to imagine the DNA being collected from all these types of lettuce and used to determine how the lettuce on our plate came to be. Try to imagine a collection of 2500 different types of lettuce: approximately 1500 varieties that were ever grown by farmers somewhere in the world and roughly 1000 populations of wild lettuce plants from roadsides and nature reserves.
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