Organogenesis in Flowers of the Homeotic Green Pistillate Mutant of Tomato (Lycopersicon esculentum)

Abstract

The flowers of a previously undescribed recessive mutant of tomato, green pistillate, show strong and consistent homeotic transformation of petals to sepals in whorl two and of stamens to carpels in whorl three. The phenotype at early and later stages is compared with wild type by scanning electron microscopy. Wild type and mutant show no difference in the pattern or timing of third whorl organ initiation, as shown by allometric analysis of scanning electron micrographs of early stages. This confirms that the mechanisms governing organ identity are distinct from those governing the positions and numbers of organs initiated; the former can be altered without changes in the latter. Mutant and wild type organs are compared by allometric analysis of dimensions of flowers dissected throughout development. The sepaloid petals (whorl 2) and the carpelloid stamens (whorl 3) in the mutant elongate at relative rates normal for the wild type organ of the whorls they occupy. This suggests that some aspects of organ growth, such as elongation rate, may also be independent of mechanisms governing organ identity.