The combination of Neosartorya (Aspergillus) fischeri antifungal proteins with rationally designed γ-core peptide derivatives is effective for plant and crop protection

Plant pathogenic fungi are responsible for enormous crop losses worldwide. Overcoming this problem is challenging as these fungi can be highly resistant to approved chemical fungicides. There is thus a need to develop and introduce fundamentally new plant and crop protection strategies for sustainable agricultural production. Highly stable extracellular antifungal proteins (AFPs) and their rationally designed peptide derivatives (PDs) constitute feasible options to meet this challenge. In the present study, their potential for topical application to protect plants and crops as combinatorial biofungicides is supported by the investigation of two Neosartorya (Aspergillus) fischeri AFPs (NFAP and NFAP2) and their γ-core PDs. Previously, the biofungicidal potential of NFAP, its rationally designed γ-core PD (γNFAP-opt), and NFAP2 was reported. Susceptibility tests in the present study extended the in vitro antifungal spectrum of NFAP2 and its γ-core PD (γNFAP2-opt) to Botrytis, Cladosporium, and Fusarium spp. Besides, in vitro additive or indifferent interactions, and synergism were observed when NFAP or NFAP2 was applied in combination with γNFAP-opt. Except for γNFAP2-opt, the investigated proteins and peptides did not show any toxicity to tomato plant leaves. The application of NFAP in combination with γNFAP-opt effectively inhibited conidial germination, biofilm formation, and hyphal extension of the necrotrophic mold Botrytis cinerea on tomato plant leaves. However, the same combination only partially impeded the B. cinerea-mediated decay of tomato fruits, but mitigated the symptoms. Our results highlight the feasibility of using the combination of AFP and PD as biofungicide for the fungal infection control in plants and crops.