A scanning electron microscope study of the development and surface features of floral organs of tomato (Lycopersicon esculentum)

Abstract

The initiation and development and the surface features of floral organs of tomato (Lycopersicon esculentum Mill.) were examined using scanning electron microscopy. After the transformation of the vegetative apex into the floral apex, the floral organs appeared in the following sequence: sepals, petals, stamens, and carpels. The pattern of initiation was helical for the sepals and simultaneous for petals, stamens, and carpels. There was a progressive increase in the diameter of the apex associated with the initiation of each whorl of organs. Following initiation, the sepal and petal primordia fused at the basal region by "zonal growth," but the cohesion of anthers to form a staminal tube occurred later in development and was achieved by the interlocking of epidermal hairs produced on the lateral and adaxial surfaces of anthers. Carpel primordia were produced at the circumference of the remaining meristem and were fused laterally early in development. Epidermal hairs of different types and frequencies were observed on the adaxial and abaxial surfaces of sepals and petals and on the adaxial and lateral surfaces of the anthers. In the gynoecium, hairs were present only on the lower half of the style and were absent on the ovary. Stomata were observed on the sepals, petals, and style, but not on the anthers or ovary. Raised stomata were present only on young developing sepals and the style and were absent on mature organs. Cuticular thickenings were also observed on the abaxial surfaces of sepals, petals, and stamens, but not on the gynoecium.