K. Noda et al., FLOWER COLOR INTENSITY DEPENDS ON SPECIALIZED CELL-SHAPE CONTROLLED BY A MYB-RELATED TRANSCRIPTION FACTOR, Nature, 369(6482), 1994, pp. 661-664
Flower colour is determined primarily by the production of pigments, u
sually anthocyanins or carotenoids, but the shade and intensity of the
colour are often changed by other factors such as vacuolar compounds,
pH and metal ions(1,2). Pigmentation can also be affected by the shap
e of epidermal cells, especially those facing prospective pollinators(
3,4). A conical shape is believed to increase the proportion of incide
nt light that enters the epidermal cells, enhancing light absorption b
y the floral pigments, and thus the intensity of their colour. We have
identified a gene (mixta) that affects the intensity of pigmentation
of epidermal cells in Antirrhinum majus petals. The cells of the corol
la lobes fail to differentiate into their normal conical form in mixta
mutants. We have cloned the mixta gene by transposon tagging; its seq
uence reveals that it encodes a Myb-related protein that probably part
icipates in the transcriptional control of epidermal cell shape.