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Evolutionary developmental genetics of floral symmetry: The revealing power of Linnaeus' monstrous flower
Author(s) -
Theißen Günter
Publication year - 2000
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/(sici)1521-1878(200003)22:3<209::aid-bies1>3.0.co;2-j
Subject(s) - biology , antirrhinum majus , gene , mutant , genetics , domestication , phenotype
Actinomorphic flowers have several planes of reflectional symmetry while zygomorphic flowers have just one. In a number of independent cases, actinomorphic flowers have arisen from zygomorphic ones during evolution. A famous example, studied by Linnaeus, is an actinomorphic variety of the common toadflax Linaria vulgaris . It has been shown now that this mutant carries a defect in LCYC , a homolog of the CYC gene, which controls zygomorphy in Antirrhinum majus . (1) Interestingly, the mutant phenotype is not due to changes in the LCYC nucleotide sequence but rather to an extensive, heritable methylation of the gene. (1) A second gene controlling zygomorphy in snapdragon, DICH , has recently also been shown to be a CYC homolog and both genes share significant sequence similarity with TB1 , one of the key genes of maize domestication. The respective family of genes, probably encoding transcription factors, might thus become both a useful instrument and a target of future plant evolutionary developmental genetics. BioEssays 22:209–213, 2000. © 2000 John Wiley & Sons, Inc.