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.