Molecular control of flower development in Petunia hybrida

Publisher Summary The flowers of higher plants are vital and often beautiful organs which are essential in plant reproduction. Flowering is induced after a period of vegetative growth by a combination of internal factors, such as hormones and gene products, and by environmental cues, including light, temperature, and water availability. A typical dicot flower consists of four different floral organs—sepal, petal, stamen, and carpel—and each organ type develop according to its relative position within the flower bud. The genus Petunia belongs to the family Solanaceae and to date approximately 30 species have been described. In the vegetative phase, leaf primordia are produced alternately along the stem and axillary buds develop which do not elongate until flowering starts. In petunia a non–autonomous transposable element has been isolated and characterized. Petunia mutants have been obtained by a variety of mutagenic treatments including ethyl–methane sulphonate (EMS), irradiation by gamma–rays and X–rays and by random transposon tagging. Flowering is controlled by several endogenous factors and environmental stimuli, including daylength and vernalization. The identity of floral organs is determined by homeotic genes. Homeotic mutants develop organs at positions normally occupied by other organs. To-date no petunia A type gene has been isolated, but the phenotype of the petunia blind mutant (Plate If) resembles the phenotype of weak alleles of Arabidopsis A–type mutants. In several aspects petunia flower development is regulated in a similar way to that in Arubidopsis and Antirrhinurn.