Integration of tomato reproductive developmental landmarks and expression profiles, and the effect of SUN on fruit shape

Universally accepted landmark stages are necessary to highlight key events in tomato reproductive development. In this study, we provide a description of floral and fruit development in a red-fruited closely related wild relative of tomato, Solanum pimpinellifolium accession LA1589. We use established and propose new landmarks as the framework for the characterization of the tomato fruit shape gene SUN in fruit development. SUN controls fruit shape predominantly after fertilization and its effect reaches a maximum at 8 days post anthesis coinciding with fruit landmark 4 representing the globular embryo stage of seed development. We also analyzed gene expression profiles of floral buds 10 days before anthesis (floral landmark 7), anthesis-stage flowers (floral landmark 10 and fruit landmark 1), and 5 days post anthesis fruit (fruit landmark 3). The expression profiles of the NILs that differ at sun showed that 34 genes were differentially expressed and most of them at a less than 2-fold difference. However, many genes were differentially expressed between the developmental times points, including many genes involved in phytohormone biosynthesis or signaling as well as organ identity and patterning of tomato fruit. Three biological replicates were conducted with three sets of LA1589 sun NILs that differ at sun growing during different time periods resulting in 3 time points x 2 genotypes x 3 replicates = 18 array hybridizations.