Triangle of U

The triangle of U (/uː/ OO) is a theory about the evolution and relationships among the six most commonly known members of the plant genus Brassica. The theory states that the genomes of three ancestral diploid species of Brassica combined to create three common tetraploid vegetables and oilseed crop species.^[1] It has since been confirmed by studies of DNA and proteins.^[2]

The theory is summarized by a triangular diagram that shows the three ancestral genomes, denoted by AA, BB, and CC, at the corners of the triangle, and the three derived ones, denoted by AABB, AACC, and BBCC, along its sides.

The theory was first published in 1935 by Woo Jang-choon,^[3] a Korean-Japanese botanist (writing under the Japanized name "U Nagaharu").^[4] Woo made synthetic hybrids between the diploid and tetraploid species and examined how the chromosomes paired in the resulting triploids.

^ Jules, Janick (2009). Plant Breeding Reviews. Vol. 31. Wiley. p. 56. ISBN 978-0-470-38762-7.
^ Xue, JY; Wang, Y; Chen, M; Dong, S; Shao, ZQ; Liu, Y (2020). "Maternal Inheritance of U's Triangle and Evolutionary Process of Brassica Mitochondrial Genomes". Frontiers in Plant Science. 11: 805. doi:10.3389/fpls.2020.00805. PMC 7303332. PMID 32595682. Comparative genomic analyses can assign the subgenomes of the allotetraploids, B. juncea and B. napus, with their diploid parental taxa, and the results were in agreement with U's triangle (Chalhoub et al., 2014; Yang et al., 2016a). [...]
^ Nagaharu U (1935). "Genome analysis in Brassica with special reference to the experimental formation of B. napus and peculiar mode of fertilization". Japan. J. Bot. 7: 389–452.
^ "인터넷 과학신문 사이언스 타임즈" (in Korean). Archived from the original on 2007-09-27.

[jules2009-1] Jules, Janick (2009). Plant Breeding Reviews. Vol. 31. Wiley. p. 56. ISBN 978-0-470-38762-7.

[pmid32595682-2] Xue, JY; Wang, Y; Chen, M; Dong, S; Shao, ZQ; Liu, Y (2020). "Maternal Inheritance of U's Triangle and Evolutionary Process of Brassica Mitochondrial Genomes". Frontiers in Plant Science. 11: 805. doi:10.3389/fpls.2020.00805. PMC 7303332. PMID 32595682. Comparative genomic analyses can assign the subgenomes of the allotetraploids, B. juncea and B. napus, with their diploid parental taxa, and the results were in agreement with U's triangle (Chalhoub et al., 2014; Yang et al., 2016a). [...]

[woo1935-3] Nagaharu U (1935). "Genome analysis in Brassica with special reference to the experimental formation of B. napus and peculiar mode of fertilization". Japan. J. Bot. 7: 389–452.

[4] "인터넷 과학신문 사이언스 타임즈" (in Korean). Archived from the original on 2007-09-27.

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