Microbial warfare against nematodes: A review of nematicidal compounds for horticulture, environment, and biotechnology
Swati Meel, Baljeet Singh Saharan
Abstract
Plant-parasitic nematodes (PPNs) pose a significant threat to global agriculture, with annual crop losses estimated at $157 billion. Although synthetic nematicides are effective, their extensive use raises concerns for environmental and human health, highlighting the need for safer, sustainable alternatives in horticulture and environmental biotechnology. This review delves into microbial strategies against PPNs, focusing on biocontrol agents (BCAs) such as bacteria and fungi that produce nematicidal compounds, including volatile organic compounds (VOCs), secondary metabolites, toxins, and extracellular enzymes. These BCAs, often attracted by plant root exudates, interact within the rhizosphere to suppress nematodes, offering promising, eco-friendly control methods for sustainable agriculture. Advances in multi-omics techniques-proteomics, transcriptomics, metabolomics, and metagenomics-have accelerated the discovery of novel nematicidal compounds, paving the way for new applications in biocontrol. Notably, nematophagous fungi (NF), present in diverse taxa such as Ascomycota and Basidiomycota, exhibit significant potential through direct (e.g., parasitism, toxin production) and indirect (e.g., lifecycle disruption) effects on nematodes. This review underscores the ecological roles, taxonomy, and mechanisms of NF in sustainable horticulture and agriculture and advocates for the integration of microbial biocontrol within an integrated pest management (IPM) framework. Such an approach is essential to reduce reliance on synthetic pesticides, enhance nematode control, and promote resilient agroecosystems.