Molecular mechanisms and phytomolecules as source of resistance for sustainable management of root knot nematode infestations in horticultural crops: A review

Root-knot nematodes (RKN) (Meloidogyne spp.) pose a major threat to horticultural crop production globally. Despite yield loss, use of synthetic chemicals to suppress RKN in horticulture crops raised concerns over produce residual toxicity, increased pest tolerance, and environmental chemical persistence. In order to address these issues, sustainable pest management practices are essential to tackle RKN infestation in horticultural crops, while maintaining ecological balance and environmental safety, apart from ensuring nutritional security for humans. The different mechanisms of RKN infestation at molecular level in horticultural crops and their interaction with plants through nematode associated molecular patterns have been discussed. The review emphasizes on sustainable pest management strategies by deciphering the efficiency of phytomolecules in different forms as bionematicides, role of plant signalling molecules in triggering innate immunity of plants and exploring crop wild relatives as resistant rootstocks in imparting resistance against invading nematodes in horticultural crops. Phytomolecules reported as bionematicides against RKNs in horticultural crops includes quercetin, caryophyllene, medicagenic acid, 1,4-naphaloacetic acid, allicin and prodelphinidin along with essential oils (castor and mint), organic acids (humic acid, acetic acid, and maleic acid), volatile organic compounds (dimethyl disulfide) and(methoxymethyl)-benzene. In addition, practical usage of plant bionematicides, challenges and future perspectives for efficient use of phytomolecules as source of resistance and as an ecofriendly approach for management of RKN, including bibliometric analysis of phytochemical based bionematicides has been discussed in detail. The review will help in addressing the research gaps and in developing effective bionematicides from plant source for sustainable pest management in horticultural crops.