Orange Peel Waste-Derived White-Rot Fungus Digestate: A Promising Approach to Enhance Plant Resistance against Botrytis cinerea

Erika Bellini ¹, Riccardo Lorrai ², Andrea Tonanzi ², Simone Ferrari ²

Dipartimento di Biologia, Università di Pisa, Via Luca Ghini 13, 56126, Pisa; Dipartimento di Biologia e Biotecnologie “Charles Darwin”, Sapienza Università di Roma, p.le Aldo Moro 5, 00185 Roma ¹, Dipartimento di Biologia e Biotecnologie “Charles Darwin”, Sapienza Università di Roma, p.le Aldo Moro 5, 00185 Roma ²

Agriculture requires an intensive application of pesticides to protect plants from harmful organisms. However, excessive use has led to environmental pollution and increased pathogen resistance. The use of plant elicitors is an environmentally friendly strategy that enhances plant resistance by triggering immunity. We developed a green protocol to produce elicitors from agro-industrial waste by exploiting the white-rot fungus Phanerochaete chrysosporium. Interestingly, the culture filtrates exhibited only weak antifungal activity against Botrytis cinerea, suggesting their primary mode of action is through elicitation of plant defenses rather than direct pathogen inhibition. To evaluate their efficacy, we treated Arabidopsis thaliana seedlings with Pasteur-sterilized filtrates and examined the expression of defense-related genes: PHYTOALEXIN DEFICIENT 3 (PAD3), PATHOGENESIS-RELATED 1 (PR-1), and PLANT DEFENSIN 1.2 (PDF1.2). In addition, adult plants sprayed with the filtrates were analyzed for callose deposition, a hallmark of immune responses, and their resistance to B. cinerea was assessed. The results showed that the filtrate: i) upregulated PAD3 expression in seedlings, ii) promoted callose accumulation in treated leaves, and iii) significantly enhanced resistance to B. cinerea. Further investigation revealed that the resistance mechanism is dependent on the jasmonic acid pathway but independent of ethylene signaling. Plants carrying mutations in CORONATINE INSENSITIVE1 (COI1) failed to respond to the filtrate, while ETHYLENE-INSENSITIVE PROTEIN 2 (EIN2) mutants exhibited responses comparable to wild-type plants. Moreover, weekly applications of the filtrate progressively increased resistance in a dose-dependent manner. HPAEC-PAD analysis identified oligosaccharides in the filtrate, compounds known to act as immune activators in plants. Finally, we demonstrated that commercial Solanaceae crops, including tomatoes, eggplants, and peppers, benefited from filtrate treatments, showing enhanced resistance to pathogens without compromising yield. This approach highlights the potential of utilizing agro-industrial waste to develop sustainable plant protection strategies.

Main author career stage: Postdoc / Fellow

Contribution type: Talk

First choice session: 4. Structure, physiology, and development

Second choice session: 3. Biodiversity and global change