Flower development schedule in tomato Lycopersicon esculentum cv. sweet cherry

The ontogeny of tomato (Lycopersicon esculentum cv. sweet cherry) flowers was subdivided into 20 stages using a series of landmark events. Stamen primordia emergence and carpel initiation occur at stage 4; archesporial and parietal tissue differentiate at stage 6 and meiosis in anthers begins at stage 9. Subepidermal meristematic ovule primordia are formed on the placenta at stage 9; megasporogenesis begins at stage 11-12 and embryo sac differentiation and ovule curvature take place at stage 14, once the pollen is maturing. We established a correlation between the characteristic cellular events in carpels and stamens and morphological markers of the perianth. The model of tomato flower development schedule was then used to analyse the spatial, temporal and tissue-specific expression of gene(s) involved in the regulation of floral organ development. As an example, the expression pattern of ORFX, a gene controlling cell size in tomato fruits, shows that expression starts very early during the ontogeny of reproductive organs.