• hypoxia
• fruit ripening
• ERF.E
• Arginyl-tRNA Transferase
• Solanum lycopersicum

In the present work, I present the approaches and results aimed at elucidating the role of endogenous hypoxic conditions in development and ripening of tomato fruits (Solanum lycopersicum cv. Microtom). Measurements of oxygen level in tomato showed that the oxygen concentration is lower than that of the ambient atmosphere. Furthermore, the level of oxygen varies among different tissues, identifying the presence of steep oxygen gradients at late ripening stages. To evaluate the physiological and molecular consequences of this endogenous hypoxic condition occurring in tomato fruits during ripening, we analyzed the expression level of hypoxia marker genes in several tissues of tomatoes harvested at different ripening stages. Such genes are expected to be regulated by low oxygen conditions via orthologues of the Arabidopsis ERF-VII transcription factors. Therefore, I focused on the role of tomato ERFs.E transcription factors in oxygen sensing in tomato, possibly via the N-end rule proteolytic pathway. To further elucidate the function of the N-end rule pathway in fruit ripening, I studied on the activity of the tomato Arginyl-tRNA Transferase (SlATE), by means of genetic complementation in Arabidopsis thalaina as well as silencing strategies in tomato. Finally, my work also included the stable transformation of tomato plants with the construct HRPE:GUS:GFP, which is expected to act as an output reporter for low oxygen conditions in plant tissues, including fruits.