Regulation of the fusion of floral organs by temperature and gibberellic acid in the normal and solanifolia mutant of tomato (Lycopersicon esculentum)

Abstract

The flowers of a single gene homozygous recessive solanifolia (sf/sf) mutant of tomato (Lycopersicon esculentum) possess separate sepals, petals and stamens, and a gynoecium that consists of several carpels with separate styles. In contrast, in the normal tomato (cv. Pearson), floral organs of each whorl are either partially or completely fused. Different temperature conditions and gibberellic acid treatments had no effect on the ontogenetic fusion of sepals and petals of the mutant and normal flowers. However, low temperatures and gibberellic acid induced the separation of stamens and pistil in many of the normal flowers, and they enhanced the separation of carpels in mutant flowers. In contrast, high temperatures and 2-chlo-roethyltrimethyl ammonium chloride, an inhibitor of gibberellin biosynthesis, promoted the fusion of stamens and gynoecia of mutant flowers, but had no apparent effect on the normal flowers. The nonfusion of stamens and carpels, in both genotypes, was associated with an increase in the number of these organs, whereas their fusion was accompanied with a reduction in their number. It is proposed that the nonfusion of floral organs in the sf/sf mutant is partly related to changes in endogenous growth substances which, through an effect on the size of the floral apex, affect the number and fusion of stamens and carpels.