COLOUR isn鈥檛 everything: sometimes it鈥檚 the feel of a flower that makes bees
prefer one over another.
About 80 per cent of flowering plants have cone-shaped cells on the surface
of their petals, while others have flat cells. In general, bees tend to prefer
pollinating those with cone-shaped cells leading scientists to assume that
conical cells had an advantage over flat cells because they produce more
attractive colours.
Beverley Glover at Cambridge University and Cathie Martin of the John Innes
Centre in Norwich weren鈥檛 so sure. They hoped to test the idea by tinkering with
plant genetics. 鈥淲e can now look at specific components of what makes a plant
attractive to pollinators,鈥� says Glover.
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The researchers altered a gene of the flower Antirrhinum majus,
which normally has conical-shaped cells. This created a flat-celled mutant form
with a slightly different colour. By cross-breeding with different varieties,
the researchers came up with two identically coloured white varieties of the
antirrhynum, some with conical and some with flat cells.
It turned out that bees still preferred to pollinate flowers with cone-shaped
cells. Colour seemed not to make a difference, Glover and Martin report in the
current issue of Heredity(vol 80, p 778).
鈥淔lat-celled flowers are not being visited as often as conical-celled
ones鈥攂ees are detecting a difference,鈥� says Glover. She suspects the bees
use their antennae to feel the textures on the surfaces of the flowers, and they
strongly associate the feel of the conical cells with the reward of nectar.