Underground guardians: how collagen and chitin amendments shape soil microbiome structure and function for Meloidogyne enterolobii control.

Background: The emergence of the guava root-knot nematode (Meloidogyne enterolobii) poses a significant threat to tomato yields globally. This study evaluated the impact of collagen and chitin soil amendments on soil microbial composition and function (fungal and bacterial communities) and their effects on tomato plant health and M. enterolobii infection under standard (5000 eggs plant^-1) and high (50,000 eggs plant^-1) inoculum pressure. Conducted in a greenhouse setting, the study investigated the effectiveness of these amendments in nurturing beneficial microbial communities across both native and agricultural soils.

Results: Both collagen and chitin were effective in reducing nematode egg counts by up to 66% and 84% under standard and high inoculum pressure, respectively, and enhanced plant health parameters (biomass and chlorophyll content). Moreover, a microbiome shift led to an increase in bacterial (Kitasatospora, Bacillus, and Streptomyces) and fungal (Phialemonium) genera, known for their chitinase, collagenase, and plant-parasitic nematode control. Among the microbes, Streptomyces spp. were found among the core microbiome and associated with a lower disease incidence assessed through a phenotype-OTU network analysis (PhONA). Under standard inoculum, higher metabolite expression was observed with amino acids representing a majority among the metabolite groups.

Conclusions: The findings highlight the potential of collagen and chitin to mitigate M. enterolobii infection by fostering beneficial soil microbial communities. Video Abstract.