THE ROLE OF SLMYB GENE IN TOMATO FRUIT DEVELOPMENT

The transcription factors regulate the levels of RNA and protein through various processes. Fruit set and fruit development are key process in the life cycle of plants. Fruits provide a suitable environment for the development of seeds and often contribute in the efficient dispersal of mature seeds and also have a high economic impact on the agricultural point of view. The present study aims to characterize the function of SlMYB (Solanum lycopersicum MYB) as a candidate gene involved in fruit set process.To achieve that, various methods and techniques were used in this study like in silico analysis, cytolocalization analysis, qPCR , in situ hybridization and plant transformation. Results from in silico analysis showed that the deduced protein has 195 amino acids with a conserved MYB DNA-binding domain composed of two conserved repeat (R2R3) characteristic of plant transcription factors. Cytolocalization analysis showed that SlMYB protein was localized in the nucleus and cytoplasm. qPCR results showed that SlMYB gene is expressed only in the reproductive tissues, where the highest level of expression occurs in pollinated flowers. qPCR and in situ hybridization results showed that the transcript of SlMYB gene was mainly found in the stamens and ovaries, suggesting that SlMYB may be involved in pollination process and ovary development. To clarify the role of SlMYB gene, gain of function experiment were done by the production of transgenic plants contain the gene of interest overexpressed, characterization of  the third generation of transgenic plants showed that the overexpression of the SlMYB gene led to the production of fruit with a large number of seeds. Conversely, silencing of SlMYB gene was done by using virus-induced gene silencing (VIGS) methodology and the silencing led to the reduction of fruit set percentage 13.4%:35.1% in silenced plants and 61.25% in control plants and the production of low number of fruits with very low number of seeds compared to the control plants. To confirm the result of silencing, RNAi methodology was used and the results also showed that the silencing of SlMYB gene led to the reduction of pollen grain fertility and ovary development consequently leading to prevention of fruit set and fruit development. It has been concluded that this gene may involve in flower development and seed formation.