Fungal diseases caused by Fusarium spp. significantly threaten food security and sustainable agriculture. One of the traditional strategies for eradicating Fusarium spp. incidents is the use of chemical and synthetic fungicides. The excessive use of these products generates environmental damage and has negative effects on crop yield. It puts plants in stressful conditions, kills the natural soil microbiome, and makes phytopathogenic fungi resistant. Finally, it also causes health problems in farmers. This drives the search for and selection of natural alternatives, such as bio-fungicides. Among natural products, algae and cyanobacteria are promising sources of antifungal bio-compounds. These organisms can synthesize different bioactive molecules, such as fatty acids, phenolic acids, and some volatile organic compounds with antifungal activity, which can damage the fungal cell membrane that surrounds the hyphae and spores, either by solubilization or by making them porous and disrupted. Research in this area is still developing, but significant progress has been made in the identification of the compounds with potential for controlling this important pathogen. Therefore, this review focuses on the knowledge about the mechanisms of action of the fatty acids from macroalgae, microalgae, and cyanobacteria as principal biomolecules with antifungal activity, as well as on the benefits and challenges of applying these natural metabolites against Fusarium spp. to achieve sustainable agriculture.

Root-knot nematodes (Meloidogyne spp.) have garnered significant attention from researchers owing to the substantial damage they cause to crops and their worldwide distribution. However, controlling these nematodes is challenging because a limited number of chemical pesticides and biocontrol agents are effective against them. Here, we demonstrate that pepper rotation markedly reduces Meloidogyne incognita infection in cucumber and diminishes the presence of p-hydroxybenzoic acid in the soil, a compound known to exacerbate M. incognita infection. Pepper rotation also restructures the rhizobacterial community, leading to the colonization of the cucumber rhizosphere by two Pseudarthrobacter oxydans strains (RH60 and RH97), facilitated by enrichment of palmitic acid in pepper root exudates. Both strains exhibit high nematocidal activity against M. incognita and have the ability to biosynthesize indoleacetic acid and biodegrade p-hydroxybenzoic acid. RH60 and RH97 also induce systemic resistance in cucumber plants and promote their growth. These data suggest that the pepper root exudate palmitic acid alleviates M. incognita infection by recruiting beneficial P. oxydans to the cucumber rhizosphere. Our analyses identify a novel chemical component in root exudates and reveal its pivotal role in crop rotation for disease control, providing intriguing insights into the keystone function of root exudates in plant protection against root-knot nematode infection.

Aims This study aimed to assess the effects of phenolic acid-degrading bacteria strains on phenolic acid content, plant growth, and soil bacterial community in phenolic acid-treated soils.Methods and results The strain of interest coded as B55 was isolated from cucumber root litter, and its degradation rates of ferulic acid and p-coumaric acid were 81.92% and 72.41% in Luria-Bertani solution, respectively, and B55 was identified as Bacillus subtilis. B55 had plant growth-promoting attributes, including solubilization of inorganic phosphate and production of siderophore and indole acetic acid. Both ferulic acid and p-coumaric acid significantly restrained an increase in cucumber seedling dry biomass, while the B55 inoculation not only completely counteracted the damage of phenolic acids to cucumber seedlings and decreased the content of ferulic acid and p-coumaric acid in soil, but also promoted cucumber seedlings growth. Amplicon sequencing found that B55 inoculation changed the cucumber rhizosphere bacterial community structure and promoted the enrichment of certain bacteria, such as Pseudomonas, Arthrobacter, Bacillus, Flavobacterium, Streptomyces, and Comamonas.Conclusions B55 not only promoted cucumber seedling growth, and decreased the content of ferulic acid and p-coumaric acid in soil, but it also increased the relative abundance of beneficial microorganisms in the cucumber rhizosphere.