"In higher plants, sex determination is usually controlled by the genotype and they can be modified by various environmental factors and/or by hormones present in the plant. The mechanism by which this process is controlled in plants is still poorly understood.In melon, sex determination is governed by the identity of two genes, andromonoecious (a) and gynoecious (g). The gene a encodes for an ethylene biosynthesis enzyme, CmACS-7, that repress stamen development in female flowers. The g gene encodes for a transcription factor, CmWIP1. CmWIP1 represses indirectly CmACS-7 expression to allow stamen development. The model suggests that the two genes interact to control the development of male, female and hermaphrodite flowers.CmWIP1 gene encodes for a nuclear protein that is conserved throughout the plant kingdom and defines a new subfamily of plant zinc finger proteins. In Arabidopsis thaliana genome 6 WIPs have been identified. However, none of the WIP proteins has been functionally characterised.The goal of this proposal is to study the expression and regulation of WIP proteins in A. thaliana. We will use as a starting point the information obtained from the sequence analysis of CmWIP1 in melon to understand if the function of this protein is conserved between melon and A. thaliana. Preliminary experiments shown that ectopic expression of the CmWIP1 gene can determine the sex of A. thaliana plants. Using a combination of genetic and genomic approaches, more easily implemented in the model plant A. thaliana, we will study the involvement of WIP proteins in plant sex determinism and development. The finding and the concepts that will be gathered on the A. thaliana model system will be transferred to melon at later stage of the project. Understanding how different sexual systems in plants have evolved, we can then begin to understand how sex in general evolves."