APPLICATION OF EXOGENOUS RNAS FOR THE SILENCING OF GENES IMPLICATED IN TOMATO FRUIT SET

Fruit set is the onset of ovary growth which occurs after successful pollination and fertilization. Pollination and fertilization are negatively affected by several unfavourable environmental conditions causing loss of fruit productivity. Parthenocarpy is the development of fruit without fertilization and can be obtained by downregulating ovary growth repressors. The application of exogenous small RNAs on flowers might be exploited to silence genes that act as negative regulators of fruit setting. The use of exogenous RNAs delivered on leaves and fruits has already successfully been used as strategy to confer resistance against fungi. It has also been demonstrated that coupling RNAs to nanoparticles increases RNA stability and extends the silencing effect. The objective of this work is to produce small RNAs to silence IAA9, one of the repressors of ovary growth, and test different methods of RNA delivery to the flower buds. We have produced small RNAs homologous to the IAA9 sequence by in vitro synthesis. Layereddouble hydroxides (LDHs) nanoparticles were efficiently coupled to IAA9-RNAs and applied to emasculated flower buds in vitro. Preliminary molecular data indicate that the expression of IAA9 in emasculated ovaries treated with IAA9-RNAs/LDHs was decreased resembling the behaviour of IAA9 in WT ovaries after fertilization.