Wild Mustard

Brassica oleracea is a plant species from family Brassicaceae that includes many common cultivars used as vegetables, such as cabbage, broccoli, cauliflower, kale, Brussels sprouts, collard greens, Savoy cabbage, kohlrabi, and gai lan.

Its uncultivated form, wild cabbage, native to coastal southern and western Europe, is a hardy plant with high tolerance for salt and lime. However, its intolerance of competition from other plants typically restricts its natural occurrence to limestone sea cliffs, like the chalk cliffs on both sides of the English Channel.^[3] Wild B. oleracea is a tall biennial plant that forms a stout rosette of large leaves in the first year. The leaves are fleshier and thicker than other Brassica species—an adaptation that helps it store water and nutrients in its difficult growing environment. In its second year, it uses the stored nutrients to produce a flower spike 1 to 2 metres (3–7 ft) tall with numerous yellow flowers.

A 2021 study suggested that the Eastern Mediterranean Brassica cretica was the origin of domesticated B. oleracea.^[4] Genetic analysis of nine wild populations on the French Atlantic coast indicated their common feral origin, deriving from domesticated plants escaped from fields and gardens.^[5]

Etymology

'Brassica' was Pliny the Elder's name for several cabbage-like plants.^[6]

Its specific epithet oleracea means "vegetable/herbal" in Latin and is a form of holeraceus (oleraceus).^[7][8]

Cultivation and uses

Head of B. oleracea Botrytis group (cauliflower) growing

B. oleracea has become established as an important human food crop plant, used because of its large food reserves, which are stored over the winter in its leaves. It is rich in essential nutrients including vitamin C. It has been bred into a wide range of cultivars, including cabbage, broccoli, cauliflower, brussels sprouts, collards, and kale, some of which are hardly recognizable as being members of the same genus, let alone species.^[9] The historical genus of Crucifera, meaning "cross-bearing" in reference to the four-petaled flowers, may be the only unifying feature beyond taste.

Researchers believe it has been cultivated for several thousand years, but its history as a domesticated plant is not clear before Greek and Roman times, when it was a well-established garden vegetable. Theophrastus mentions three kinds of rhaphanos (ῤάφανος):^[10] a curly-leaved, a smooth-leaved, and a wild-type.^[11] He reports the antipathy of the cabbage and the grape vine, for the ancients believed cabbages grown near grapes would impart their flavour to the wine.^[12]

A diet rich in cruciferous vegetables (e.g., cabbage, broccoli, cauliflower) is linked to a reduced risk of several human cancers.^[13][14]

Couve Galega (ex. Brassica oleracea var. acephala DC.) for the Portuguese Caldo verde

Jersey cabbage can be cultivated to grow quite large, especially in frost-free climates.

Origins

According to the Triangle of U theory, B. oleracea is very closely related to five other species of the genus Brassica.^[15] A 2021 study suggested that Brassica cretica, native to the Eastern Mediterranean, particularly Greece and the Aegean Islands, was the closest living relative of cultivated B. oleracea, thus supporting the view that its cultivation originated in the Eastern Mediterranean region, with later admixture from other Brassica species.^[4]

Bâtons d'chour - Jersey walking sticks

The cultivars of B. oleracea are grouped by developmental form into several major cultivar groups, of which the Acephala ("non-heading") group remains most like the natural wild cabbage in appearance. For a list of these groups, see the table of cultivars.

History

Market Scene, painting by Pieter Aertsen (1569)

Through artificial selection for various phenotype traits, the emergence of variations of the plant with drastic differences in looks occurred over centuries. Preference for leaves, terminal bud, lateral bud, stem, and inflorescence resulted in selection of varieties of wild cabbage into the many forms known today.

Impact of preference

• The preference for the eating of the leaves led to the selection of plants with larger leaves being harvested and their seeds planted for the next growth. Around the fifth century BC, the formation of what is now known as kale had developed.^[16]
• Preference led to further artificial selection of kale plants with more tightly bunched leaves, or terminal bud. Somewhere around the first century AD emerged the phenotype variation of B. oleracea known as cabbage.
• Phenotype selection preferences in Germany resulted in a new variation from the kale cultivar. By selecting for fatter stems, the variant plant known as kohlrabi emerged around the first century AD.
• European preference emerged for eating immature buds, selection for inflorescence. Early records in 15th century AD, indicate that early cauliflower and broccoli heading types were found throughout southern Italy and Sicily, although these types may not have been resolved into distinct cultivars until about 100 years later.^{[17][9][18][19]}
• Further selection in Belgium in lateral bud led to Brussels sprouts in the 18th century.

Genetics in relation to taste

The TAS2R38 gene encodes a G protein-coupled receptor that functions as a taste receptor, mediated by ligands such as PROP and phenylthiocarbamide that bind to the receptor and initiate signaling that confers various degrees of taste perception. Vegetables in the brassica family, such as collard greens, kale, broccoli, cabbage, and Brussels sprouts, contain glucosinolates and isothiocyanates, which resemble PROP, and therefore much of the perceived "bitterness" of these vegetables is mediated through TAS2R38. Bitter taste receptors in the TS2R family are also found in gut mucosal and pancreatic cells in humans and rodents. These receptors influence release of hormones involved in appetite regulation, such as peptide YY and glucagon-like peptide-1, and therefore may influence caloric intake and the development of obesity. Thus, bitter taste perception may affect dietary behaviors by influencing both taste preferences and metabolic hormonal regulation.^[20]

Three variants in the TAS2R38 gene – rs713598, rs1726866, and rs10246939 – are in high linkage disequilibrium in most populations and result in amino acid coding changes that lead to a range of bitter taste perception phenotypes. The PAV haplotype is dominant; therefore, individuals with at least one copy of the PAV allele perceive molecules in vegetables that resemble PROP as tasting bitter, and consequently may develop an aversion to bitter vegetables. In contrast, individuals with two AVI haplotypes are bitter non-tasters. PAV and AVI haplotypes are the most common, though other haplotypes exist that confer intermediate bitter taste sensitivity (AAI, AAV, AVV, and PVI). This taste aversion may apply to vegetables in general.^[20][21]

Cultivars

According to the Royal Botanic Gardens (Kew Species Profiles)^[22] the species has eight cultivar groups. Each cultivar group has many varieties.

• Acephala: non-heading cultivars (kale, collards, ornamental cabbage, ornamental kale, flowering kale, tree cabbage).
• Alboglabra: Asian Cuisine cultivars (Chinese kale, Chinese broccoli, gai lan, kai lan).
• Botrytis: cultivars that form compact inflorescences (broccoli, cauliflower, broccoflower, calabrese broccoli, romanesco broccoli). Note: although technically broccoli is an inflorescence, and so it belongs to the Botrytis group, because its subspecies name is Brassica oleracea var. italica, many put it in the Italica group, including The North Carolina State University Cooperative Extension^[23])
• Capitata: cabbage and cabbage-like cultivars (cabbage, savoy cabbage, red cabbage).
• Gemmifera: bud-producing cultivars (sprouts, Brussels sprouts)
• Gongylodes: turnip-like cultivars (kohlrabi, knol-kohl)
• Italica: sprouts (purple sprouting, sprouting broccoli).
• Tronchuda: low-growing annuals with spreading leaves (Portuguese cabbage, seakale cabbage).

Notes

References

• Beckett, Emma (2014). "Bitter Taste Genetics – the Relationship to Tasting, Liking, Consumption and Health". Food & Function. 5 (12): 3040–54. doi:10.1039/C4FO00539B. hdl:1959.13/1298053. PMID 25286017.
• Boxer, E.E.; Garneau, N.L. (2015). "Rare haplotypes of the gene TAS2R38 confer bitter taste sensitivity in humans". SpringerPlus. 4: 505. doi:10.1186/s40064-015-1277-z. PMC 4574037. PMID 26405625.
• Bufe, B. (2005). "The Molecular Basis of Individual Differences in Phenylthiocarbamide and Propylthiouracil Bitterness Perception". Current Biology. 15 (4): 322–7. doi:10.1016/j.cub.2005.01.047. PMC 1400547. PMID 15723792.
• Calancie, Larissa; et al. (2018). "TAS2R38 Predisposition to Bitter Taste Associated with Differential Changes in Vegetable Intake in Response to a Community-Based Dietary Intervention". G3: Genes, Genomes, Genetics. 8 (6): 2107–2119. doi:10.1534/g3.118.300547. PMC 5982837. PMID 29686110.
• Duffy, V.B.; et al. (2010). "Vegetable Intake in College-Aged Adults Is Explained by Oral Sensory Phenotypes and TAS2R38 Genotype". Chemosensory Perception. 3 (3–4): 137–148. doi:10.1007/s12078-010-9079-8. PMC 3000691. PMID 21157576.
• Wieczorek, Martyna.; et al. (2018). "Bitter Taste of Brassica Vegetables: The Role of Genetic Factors, Receptors, Isothiocyanates, Glucosinolates, and Flavor Context". Critical Reviews in Food Science and Nutrition. 58 (18): 3130–3140. doi:10.1080/10408398.2017.1353478. PMID 28718657. S2CID 28896102.
• Rozengurt, E. "Taste Receptors in the Gastrointestinal Tract. I. Bitter taste receptors and α-gustducin in the mammalian gut". American Journal of Gastrointestinal and Liver Physiology. 7: 171–177.
• Roura, Eugeni; et al. (21 May 2015). "Variability in Human Bitter Taste Sensitivity to Chemically Diverse Compounds Can Be Accounted for by Differential TAS2R Activation". Chemical Senses. 40 (6): 427–35. doi:10.1093/chemse/bjv024. PMID 25999325.
• Risso, David; et al. (27 June 2016). "Erratum: Corrigendum: Global Diversity in the TAS2R38 Bitter Taste Receptor: Revisiting a Classic Evolutionary PROPosal". Scientific Reports. 6: 28406. doi:10.1038/srep28406. PMC 4921822. PMID 27346370.
• Mennella, Vito; et al. (20 February 2005). "Functionally Distinct Kinesin-13 Family Members Cooperate to Regulate Microtubule Dynamics during Interphase". Nature Cell Biology. 7 (3): 235–45. doi:10.1038/ncb1222. PMID 15723056. S2CID 6501199.
• Kim, U.K.; et al. (2005). "Genetics of individual differences in bitter taste perception: lessons from the PTC gene". Clinical Genetics. 67 (4): 275–80. doi:10.1111/j.1399-0004.2004.00361.x. PMID 15733260. S2CID 1639438.
• Kim, U.K.; et al. (2004). "Genetics of Human Taste Perception". Journal of Dental Research. 83 (6): 448–53. doi:10.1177/154405910408300603. PMID 15153450. S2CID 8801457.
• Khataan, Nora H.; et al. (2009). "TAS2R38 Genotypes and Phenylthiocarbamide Bitter Taste Perception in a Population of Young Adults". Journal of Nutrigenetics and Nutrigenomics. 2 (4–5): 251–6. doi:10.1159/000297217. PMID 20484932. S2CID 45496712.
• Genick, U.K.; et al. (2011). "Sensitivity of genome-wide-association signals to phenotyping strategy: the PROP-TAS2R38 taste association as a benchmark". PLOS ONE. 6 (11): e27745. Bibcode:2011PLoSO...627745G. doi:10.1371/journal.pone.0027745. PMC 3223210. PMID 22132133.