Control of Pigment Biosynthesis Genes during Petal Development.

Sexual reproduction in flowering plants depends on the evocation of flowers, which, in general, consist of four whorls of organs: sepals, petals, anthers, and pistil. Sepals and petals can be regarded as initially protective organs. During the first stage of floral development, meiosis occurs in the anthers and the pistil while these organs are still enclosed by the sepals. Petals, the organs of the second whorl of the floral meristem, start developing toward the end of meiosis. Their growth coincides with the formation of the anther filaments and the stem of the pistil. Finally, during flower maturation, the petals unfold to perform asecond function in plants pollinated by insects or birds: their color serves as a flash signal to attract pollinators, and their structure serves as a landing place. Here, we will describe one aspect of petal development, the coordinated expression of the color genes whose combined activities produce the visual signals that attract pollinators to flowers.