Towards the study of epigenetic factors influencing meiotic recombination in tomato

Meiotic recombination depends on both genetic and epigenetic information in plants as in other organisms. In Arabidopsis, it is known that crossovers (COs) are associated with active chromatin modifications, including histone methylation and acetylation, low nucleosome density, histone variant H2A.Z and low DNA methylation. The objective of this work was to translate fundamental knowledge for epigenetic control of COs from Arabidopsis to tomato in order to explore the possibilities to modulate recombination. This is essential for plant breeders to design the allelic composition of tomato chromosomes. We focused on ARP6 (ACTIN RELATED PROTEIN6), MET1 (METHYLTRANSFERASE1), DDM1 (DECREASE IN DNA METHYLATION1), HDA19 (HISTONE DEACETYLASE19) and SIRT1 (SIRTUIN1) as key recombination candidates, based on Arabidopsis literature data and our unpublished results. We identified the tomato orthologous genes by exploitation of the tomato whole-genome sequences. The in silico transcription profiles of these five genes within tomato organs revealed a wide functional role for HDA19, whereas a more specific activity was observed for the others. HDA19 and SIRT1 expression levels determined in leaves and meiotic buds of tomato using qPCR confirmed that the transcripts were highly abundant in the reproductive organs. To investigate experimentally the function of these genes, we are silencing them by RNAi approach mediated by amiRNA. Molecular and cytological analyses will be carried out on these mutants.