Antifungal activity of microalgae in phytopathogenic fungi: A systematic review

Phytopathogenic fungi are a group of organisms that cause diseases in plants through disturbances in their cellular metabolism. They have major impacts on agriculture, accounting for 8 - 40% of the losses in world agricultural production. Meanwhile, microalgae synthesize a wide variety of allelopathic chemicals and can be used for different biocidal purposes, including antifungal. The objective of this study was to review the antifungal activity of microalgal extracts and their compounds against phytopathogenic fungi. This systematic review of the literature was conducted using SciELO, PubMed, and Periódicos Capes (Scopus). Following the search, 25 articles published in English and Portuguese were selected. Several publications will be recorded from 2015 to 2022. Eight microalgal phyla (Bacillariophyta, Chlorophyta, Cyanobacteria, Haptophyta, Miozoa, Ochrophyta, Prasinodermatophyta, and Rhodophyta) were detected, with Chlorophyta and Cyanobacteria having the highest number of registered publications. The most tested species of phytopathogenic fungi were Aspergillus niger and Botrytis cinerea. Regarding the categorized inhibition classification for the assays, high inhibition was observed in 31.26% of the trials. Studies performed with cyanobacterial species showed a higher proportion of high inhibition (41.36%) of phytopathogens. Given the high degree of biodiversity of microalgae and their wide range of associated bioactive molecules, this is a vast field to explore for novel biopesticides with antifungal potential.