Overlapping local and systemic defense induced by an oomycete fatty acid MAMP and brown seaweed extract in tomato

Abstract

Eicosapolyenoic fatty acids are integral components of oomycete pathogens that can act as microbe-associated molecular patterns (MAMPs) to induce disease resistance in plants. Defense inducing eicosapolyenoic fatty acids include arachidonic (AA) and eicosapentaenoic acids, and are strong elicitors in solanaceous plants with bioactivity in other plant families. Similarly, extracts of the brown seaweed, Ascophyllum nodosum, used in sustainable agriculture as a biostimulant of plant growth, may also induce disease resistance. A. nodosum, similar to other macroalgae, is rich in eicosapolyenoic fatty acids, which comprise as much as 25% of total fatty acid composition. We investigated the response of roots and leaves from AA or a commercial A. nodosum extract (ANE) on root-treated tomatoes via RNA sequencing, phytohormone profiling, and disease assays. AA and ANE significantly altered transcriptional profiles relative to control plants, inducing numerous defense-related genes with both substantial overlap as well as differences in gene expression patterns. Root treatment with AA and, to a lesser extent, ANE also altered both salicylic acid and jasmonic acid levels while inducing local and systemic resistance to oomycete and bacterial pathogen challenge. Thus, our study highlights overlap in both local and systemic defense induced by AA and ANE, with potential for inducing broad-spectrum resistance against pathogens.

The oomycete MAMP, arachidonic acid, and anAscophyllum nodosum-derived plant biostimulant induce defense metabolome remodeling in tomato

“…Through RNA sequencing, this same study revealed a striking level of transcriptional overlap in the gene expression profiles of AA-or ANE-root-treated tomato across tested timepoints (Lewis et al 2022). Gene ontology functional analysis of transcriptomic data revealed AA and ANE enriched similar categories of genes with nearly perfect overlap also observed in categories of Domonique C. Lewis Phytopathology under-represented genes.…”

“…Previous transcriptomic work revealed a high level of congruency in differentially expressed genes in AA- and ANE-treated tomato seedlings compared to H 2 O-treated controls (Lewis et al 2022). To further this line of investigation, the metabolomic profiles of AA- and ANE-root-treated plants were compared to H 2 O after 24-, 48-, 72-, and 96-hours exposure to their respective treatments.…”

“…AA and ANE can induce disease resistance locally and systemically, alter the accumulation of key phytohormones, and change the transcriptional profile of tomato with a striking level of overlap between the two treatments (Lewis et al 2022). The current study examined and characterized the AA- and ANE-induced metabolomes of tomato.…”

“…In a parallel study we demonstrated AA’s ability to systemically induce resistance and ANE’s capacity to locally and systemically induce resistance in tomato to different pathogens (Lewis et al 2022). Further, we showed that AA and ANE altered the phytohormone profile of tomato by modulating the accumulation of defense-related phytohormones (Lewis et al 2022). Through RNA sequencing, this same study revealed a striking level of transcriptional overlap in the gene expression profiles of AA- or ANE-root-treated tomato across tested timepoints (Lewis et al 2022).…”

“…Further, we showed that AA and ANE altered the phytohormone profile of tomato by modulating the accumulation of defense-related phytohormones (Lewis et al 2022). Through RNA sequencing, this same study revealed a striking level of transcriptional overlap in the gene expression profiles of AA- or ANE-root-treated tomato across tested timepoints (Lewis et al 2022). Gene ontology functional analysis of transcriptomic data revealed AA and ANE enriched similar categories of genes with nearly perfect overlap also observed in categories of under-represented genes.…”