THE REGULATION OF GENE EXPRESSION IN GRAPEVINE FLOWERING PROCESS

The climate changes are rapidly mutating the delicate balances which established among different living organisms in relation to environments and ecosystems. These balances are the result of a millennial adaptation process flowing slowly and inexorably up to continuatively reach an ever new and dynamic equilibrium, which reward the suitable organisms and mow the unadapt ones. Global warming, ecosystems destruction and catastrophic extreme events are increasingly rising from uncontrolled anthropic activities and the area par excellence that is suffering the heaviest repercussions is agriculture. It is of primary importance that the next goal for humankind be identified in implementation of productive systems featured by low inputs, maximization of process efficiency and high resilience to the wide fluctuations of biological and environmental parameters featuring the present era. In this regard, biotechnology could dress a first-rate role by unrevealing the plant fully potential hidden in the molecular mechanisms at the basis of crop growth, development and production. It is precisely at this point that this work fits in, or rather to try to clarify the genetic relationships at the basis of flowering process in grapevine (Vitis vinifera L.). Even if grapevine is a crop typically characterized by a dominance of vegetative propagation, there are several reasons why to be interest in shading light on this particular issue. In contrast to the historical and cultural legacies that see viticulture as an extremely conservative discipline, the importance of conventional genetic improvement of varieties is increasingly affirming. The reason for this is soon individuated if we think at plant cross as very powerful item to generate new genetic variability to employ for breeding programmes aimed to the constitutions of grapevine varieties featured by pathogen resistance, abiotic stress tolerance and specific qualitative traits of the production. By the way, quantitative and qualitative traits of the production are directly influenced by flowering, which represents the first constituted step of the reproductive phase leading to the development of the main product, the berry. The structure of the flower and the architecture of the inflorescence affect the organization of the bunch, with many consequences at the production level. Knowing all the genetic relationships and the molecular mechanisms behind the anthesis in every single actor role means to be able to control the entire process and to address the production in a targeted manner. To improve this kind of knowledge, it was decided to dissect grapevine flower in each single whorl: calyx, calyptra, filament, anther, stigma, ovary, and embryo in two time points representing pre- and post-anthesis phases. To identify hub genes that unequivocally distinguish the different tissues providing insights into the molecular mechanisms that are at the basis of floral whorls and tissue development, it was used an RNA-Seq approach, producing a grapevine flower transcriptome atlas. Several analytical techniques were used to gradually narrow the field, in particular weighted gene coexpression network analysis (WGCNA) and tau analysis were applied to isolate clusters of genes showing a similar expression pattern and high or absolute specificity for a given tissue, respectively. Several transcription factors (TFs) were identified within the various whorls and a subset of 17 of them was selected to be analysed with a novel technique, the DAP-Seq. This assay allows the identification of the binding sites within a genome for a given TF through the hybridization of the in vitro expressed TF-protein with the fragments of gDNA. Taking advantage from the adaptation of DAP-Seq to grapevine, the entire cistrome of the 17 TFs was discovered and the targets were crossed with the WGCNA and tau analysis data in order to have back for each TF a list of directly regulated targets, characterized by a similar [...]