Fungal chito-oligosaccharides extraction and their use as promoters of arbuscular mycorrhizal symbiosis

Abstract115° Congresso S.B.I. - Online, 9 – 11 settembre 2020312 = Fungal chito-oligosaccharides extraction and their use as promoters of arbuscular mycorrhizal symbiosisAndrea Crosino1, Elisa Moscato1, Federica Spina1, Marco Blangetti2, Gennaro Carotenuto1, Veronica Volpe1, Simone Bordignon2, Cristina Prandi2, Cristina Varese1, Roberto Gobetto2, Andrea Genre11Department of Life Sciences and Systems Biology, University of Turin, Viale P.A. Mattioli 25, 10125 Turin, Italy;2Department of Chemistry, University of Turin, V ia Pietro Giuria 7, 10125 Turin , ItalyChito-oligosaccharides (COs) are chitin derivative molecules, composed of N-acetylglucosamine (NAG) units which are present in germinated spore exudates from arbuscular mycorrhizal (AM) fungi. Chito-oligomers from AM fungi (Myc-COs) activate in the host plant a partially characterized signalling pathway, which includes the induction of repeated oscillations in nuclear Ca2+ concentration and the regulation of AM-related gene expression and root colonization by the symbiotic fungi. This symbiotic signalling role opens the way to possible COs applications as stimulants of AM establishment in crops. Commercially available short-chain COs analogous to Myc-COs are currently obtained through expensive and environmentally risky chemical processing of shrimp fishing industry wastes.The aim of this work is to isolate, characterize and test the biological activity as AM promoters of Myc-COs obtained from the biomasses of three fast-growing fungal species, as a low-cost alternative to commercially available molecules.Following chitin extraction and hydrolysis, NMR analyses were used to characterize the resulting Myc-COs, which were more acetylated than commercial COs. We then compared the effectiveness of fungal- and shrimp-derived Myc-COs in triggering nuclear Ca2+ spiking in epidermal cells of Medicago truncatula rootcultures. Lastly, the bioactivity of fungal and shrimp-derived Myc-COs was compared in M. truncatulainoculated with the AM fungus Funnelliformis mosseae. Our results indicate that the purification protocol efficiently isolates functional Myc-COs from all three fungi and their bio-activity is stronger when compared to commercial shrimp-derived COs. Production scale-up, the choice of cheaper substrates for fungal culture and an optimization of the extraction protocol are expected to reduce costs, making the use of Myc-COs in agricultural context an achievable goal in the next future