The Evolutionary History of Wild, Domesticated, and FeralBrassica oleracea(Brassicaceae)

Abstract

Understanding the evolutionary history of crops, including identifying wild relatives, helps to provide insight for conservation and crop breeding efforts. Cultivated Brassica oleracea has intrigued researchers for centuries due to its wide diversity in forms, which include cabbage, broccoli, cauliflower, kale, kohlrabi, and Brussels sprouts. Yet, the evolutionary history of this species remains understudied. With such different vegetables produced from a single species, B. oleracea is a model organism for understanding the power of artificial selection. Persistent challenges in the study of B. oleracea include conflicting hypotheses regarding domestication and the identity of the closest living wild relative. Using newly generated RNA-seq data for a diversity panel of 224 accessions, which represents 14 different B. oleracea crop types and nine potential wild progenitor species, we integrate phylogenetic and population genetic techniques with ecological niche modeling, archaeological, and literary evidence to examine relationships among cultivars and wild relatives to clarify the origin of this horticulturally important species. Our analyses point to the Aegean endemic B. cretica as the closest living relative of cultivated B. oleracea, supporting an origin of cultivation in the Eastern Mediterranean region. Additionally, we identify several feral lineages, suggesting that cultivated plants of this species can revert to a wild-like state with relative ease. By expanding our understanding of the evolutionary history in B. oleracea, these results contribute to a growing body of knowledge on crop domestication that will facilitate continued breeding efforts including adaptation to changing environmental conditions.

Different Shades of Kale—Approaches to Analyze Kale Variety Interrelations

“…Information about hybridization or introgression cannot be displayed by this method though. Nevertheless, similar to the report of Mabry, et al [ 3 ], the analysis separated wild samples from cultivated samples. Since with Bayesian inference as a character-based method, it is impossible to process SPLoSH information in MrBayes, and also more informative in terms of reticulate evolution, uncertainties and conflicting signals in the data [ 83 , 84 ], networks are a better choice [ 85 ].…”

“…For Brassica oleracea (2 n = 18), a broad range of genetic and morphological diversity exists. Its evolutionary history and domestication origin is still widely unknown [ 3 ]. Current knowledge indicates the Eastern Mediterranean as the center of domestication for B. oleracea [ 3 , 4 , 5 ], either by early cultivated forms originally from the Atlantic coast brought to this region [ 6 ], or by in situ domestication of Mediterranean wild species [ 7 ].…”

“…Its evolutionary history and domestication origin is still widely unknown [ 3 ]. Current knowledge indicates the Eastern Mediterranean as the center of domestication for B. oleracea [ 3 , 4 , 5 ], either by early cultivated forms originally from the Atlantic coast brought to this region [ 6 ], or by in situ domestication of Mediterranean wild species [ 7 ]. Studies of Schiemann [ 8 ], Lizgunova [ 9 ], and Mei, et al [ 10 ] specifically report Sicily as the geographic origin.…”

“…Studies of Schiemann [ 8 ], Lizgunova [ 9 ], and Mei, et al [ 10 ] specifically report Sicily as the geographic origin. The recent analyses of Mabry, et al [ 3 ] support B. cretica as the closest living wild relative to B. oleracea .…”

Towards a catalog of pome tree architecture genes: the draft ‘d’Anjou’ genome (Pyrus communis L.)

“…Therefore, a single reference genome does not represent the complex genome landscape, or pan-genome, for a single crop species. To understand the genetic basis of the diverse Brassica morphotypes, many attempts have been made to explore the genomes of Brassica [8][9][10][11][12] . In one of those attempts, genomes from 199 B. rapa and 119 B. oleracea accessions were sequenced and analyzed using a comparative genomic framework 10,12 .…”