Foto del docente

Stefano Del Duca

Full Professor

Department of Biological, Geological, and Environmental Sciences

Academic discipline: BIO/01 General Botany

Research

Keywords: transglutaminase autoincompatibility allergy programmed cell death reproductive biology

Characterization of sequence and structural homology as well as of the immunological and functional properties of plant transglutaminases in relation to phylogenetic distribution. Self-incompatibility in fruit trees and its importance on productivity. Role of extracellular transglutaminase in signalling and/or as adhesion factor. Modification of pollen antigens induced by climate change and its importance in pollen allergenicity and cross-allergenicity. Studies on pollen phospholipase and transglutaminase  activities and their possible involvement on allergenicity. Programmed cell death in petals: post-translational modification of proteins catalyzed by transglutaminase, localization and possible role of the enzyme. Biotic and abiotic stresses: involvement of transglutaminase and phospholipase activities. Transglutaminase as biotecnological tools to improve the features of food products



TGases are a family of enzyme involved in different physiological activities as consequences of different reactions on protein substrates (transamidation, protein cross-linking,  deamidation, GTP hydrolysis, disulphide isomerase reaction); although TGs carry out various biological functions that are generally attributed to their protein-modifying activity, in some instances their biological function is due to specialized non-catalytic actions, such as scaffolding of the cytoskeleton to maintain membrane integrity, cell adhesion and possibly signal transduction.

TGases have been found also in higher plants suggesting a widespread distribution. One of the plant form has been sequenced for the first time in this laboratory and its roles are under investigation in Arabidopsis knock-out plants. Among the different forms those of chloroplasts have a stabilizing  and protective effects on photosystems whereas those of pollen (with a localization in cell wall) are involved in the organization and modification of cell wall as well as in the interaction with extracellular matrix

Some of these forms are under investigation to check their sequence and structural homology as well as their immunological and functional properties. Some of previous data have been shown the presence of enzyme also in unicellular green alga. Research are in progress to verify the distribution of TGases also in other plant organisms to evaluate the distribution in relation to phylogeny.

In style/stigma-pollen self incompatibility of fruit tree, the role of extracellular TGase will be evaluated as molecular signal and/or adhesion factor. The products of TGase catalysis will be studied on: 1) proteins encoded by locus S, as ribonuclease, 2) proteins involved in the incompatibility mechanisms as the cytoskeleton, cell wall and extracellular proteins, 3) proteins responsible of cellular adhesion.

The main objectives are: purification of pollen TGase and its biochemical characterization; evaluate a possible role of TGase in self-incompatibility response in fruit tree where the regulative mechanisms of compatibility is strictly related to fruit production having indeed strong agro-economical implications.

A streak of research concern the possible involvement of TGase in the increase of allergy to pollen treated to stress factors related to climate changes; this hypothesis is based on the unequivocal increase of allergy due to climate changes and to the general involvement of TG during stress but also in asthma disease. The TGase mechanism of action seem related to the modification of antigen located in the pollen cell wall or in the activation phospholipase A2, a factor responsible of inflammation response after the contact with pollen. About the research on the plant programmed cell death (PCD), as this phenomena is not completely understood (in particular at cellular compartments level), the activity is addressed to clarify the involvement of TGase in PCD phenomena. The corolla of Nicotiana tabacum will be the model in which to study the presence and the activity of enzyme during growth, senescence and cell death also in sub-cellular fraction enriched in chloroplasts, cell walls, cytosol and microsomes. Parallely also the effects of polyamines (substrates of TG in the transamitading reaction) will be checked on the senescence by evaluating the amount and the last of supply. Part of the research concern applicative aspect in the horticultural sectors by with the aim to slow the senescence process in the cutted flowers by the use of molecules with a low impact on the environment.

The study on biotic and abiotic stresses will be perform on tobacco plant in which the biotic stress as the HR response due to virus infection and the mechanical stress due to wound will be studied. In both cases the TGase activity will be analysed and the comparison of the two types of stress will allow to understand if one or both stress could have an influence on TGase activity and indeed if TGase could be involved in the molecular mechanisms of response to stresses.