This project aims at elucidating the role and dynamics of bioactive oligosaccharides derived from the plant extracellular matrix [ECM, also indicated as cell wall (CW)], acting as regulatory molecules in both immunity and development. A main focus of the project is on oligogalacturonides (OGs), oligosaccharides deriving from the fragmentation of the homogalacturonan (HGA), a main component of pectin in the CW, that act as damage-associated molecular patterns (DAMPs). In animals, hyaluronan, also a linear negatively charged polysaccharide that can be considered the vertebrate counterpart of HGA, is a molecular powerhouse with critical roles in homeostasis and disease onset, progression, and recovery, and its fragments are potent inducers of immunity and therefore classical DAMPs. Although OGs are the first DAMPs ever discovered, much is unknown about their biology due to the complexity of their mediated signaling and the difficulty of isolating mutants defective in specific or general responses to OGs. By exploiting unique tools and expertise developed in many years, this project aims at proving the hypothesis that OGs, besides acting as DAMPs when present at high levels in stress conditions, also play a role in development when they are released at low levels during the physiological cell wall remodeling. Moreover, it aims at dissecting the pathways involved in the role of OGs as mediator of the growth-defense trade-off and elucidating their possible interplay with fragments derived from another important cell wall component, cellulose, that are described as a novel class of DAMPs. Finally, the project aims at demonstrating that inactivation of CW fragments accomplished by newly discovered specific oxidases belonging to the complex berberine bridge enzyme-like family is a homeostatic mechanism that prevents hyper-accumulation of OGs and hyper-immunity. Disentangling the mechanisms of CW--mediated signaling may lead to novel strategies of crop protection.
This research will address the mechanisms that control immunity triggered by signals derived from the extracellular matrix to prevent deleterious effects. DAMP homeostasis mechanisms are relevant not only for plant biologists but also for researchers working in the animal field. Oxidation-based mechanisms may contribute to HA homeostasis and be searched using strategy similar to that adopted in our work. Overall, this proposal will provide the basic knowledge and expertise that will be relevant to exploit for enhancing response to pathogens in crop plants with little or no effects on growth and yield, and more in general, for plant biotechnology.
Plant diseases are a major cause of economic losses, decreased yield and toxin contamination of food products. Too often control of disease relies on the use of health-threatening and environmentally dangerous pesticides; in other cases, no treatment is available or it is very costly. A promising disease control strategy is the enhancement of natural plant resistance; however, the growth-defence tradeoff may result in decreased growth and yield. In particular, negative effects on root development and performance have a very important impact on crop growth, quality and yield. Therefore, the understanding of the developmental and architecture dynamics in relation to immunity as well as to cell wall structure is central for breeding and biotechnological efforts aimed at enhancing yield and reducing losses caused by microbial pathogens.
This project addresses all three objectives of the Horizon 2020 Framework Programme [Excellent Science; Competitive Industries; Societal Challenge], as part of the implementation of the Europe 2020.