Van Gogh's Sunflower Paintings

Botany

Doris Elster, doris.elster@uni-bremen.de | 14/07/12 | Bremen, Germany

Vincent van Gogh’s series of sunflowers in a vase show beside the familiar blossoms with marginal yellow ray florets and dark tubular florets in the middle also flower heads with entirely yellow, double-flowered blossoms. How did this genetic variation evolve?

Crossing experiments with sunflowers

If we cross species of a regular wild-type sunflower Helanthus annuus with pure yellow, double-flowered representatives then we will recognize mutants among the descendants with regular flower heads and double-flowered blossoms. Therefore, researchers suggested that a single dominant gene causes the mutation of double-flowered blossoms. However, further crossings showed a third variety with marginal and central tubular florets. Scientists, therefore, concluded that there is a second mutation which is present in regular as well as in double-flowered blossom.

 

 

A+B Sunflower with marginal ray florets and tubular florets insideA+B Sonnenblume mit Röhrenblüten im Inneren und Zungenblüten am Rand

C+D Sunflower (double-flowered) with ray florets outside and inside

E+F Sunflower with tubular florets outside and inside

G Van Gogh’s painting of sunflowers, arrows indicate mutants

Image source: Chapman, M.A. et al. (2012)

A single gene causes variation

Researchers identified gene HaCYC2c as the cause for different flower head variations. They have screened hundreds of sunflowers – wild-type plants, double-flowered species and those with tubular florets. It was found that sunflowers with a yellow-brown blossom do not show a mutation of gene HaCYC2c. In plants with uniformly yellow petals, however, the “switch gene” has mutated. As a result, the genes causing yellow petals were also active in places where the inner tubular florets should originally develop. In species which increasingly form tubular florets instead of long yellow petals the “switch gene” was inactive. Here researchers found a defective gene copy which prevented the formation of yellow petals.

Switch gene HaCYC2c also responsible for mutations of other garden plants

Researchers were able to prove that van Gogh’s paintings show sunflower mutants. They have showed this by classical crossing experiments. Gene HaCYC2c, as identified in sunflowers, is also available in other beaming flowers (sind hier Asteraceae gemeint?) like Gerberas and Dahlias. The study provides an insight in molecular mechanism of plants which are economically interesting: be it seedy crop or pretty garden flowers. Also, it is emphasized that genetic variations influence biodiversity within plant families.

Source

Chapman, M.A. et al. (2012): Genetic Analysis of Floral Symmetry in Van Gogh's Sunflowers Reveals Independent Recruitment of CYCLOIDEA Genes in the Asteraceae. PLoS Genet 8(3): e1002628. doi:10.1371/journal.pgen.1002628 

 http://www.pflanzenforschung.de/node/1715?pk_campaign=RSS

 

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