Seaweeds contain many biological components including proteins, peptides, amino acids, fibers, lipids, pigments, phenols, and polysaccharides, making them an attractive source for potential agricultural and health benefits.

Insects and pathogenic infections (bacteria, viruses, and fungi) cause huge losses in agriculturally important crops yearly. Due to the rise in pesticide and antibiotic resistance, our crops and livestock are increasingly at risk.

There is a rising demand for environmentally friendly solutions to prevent crop decreases. Components of Ascophyllum nodosum seaweed extracts were recently found to boost plant immunity.

Plant immune response

The stimulatory activities of the A. nodosum marine algae-derived extract (Stella Maris®) were investigated in a broad range of immune assays. Elevated hydrogen peroxide production measured in a chemiluminescence assay suggested that the extract elicited a strong burst of reactive oxygen species.

Arabidopsis seedlings treated with Stella Maris® activated the expression ofWRKY30, CYP71A12 and PR-1 genes, the induction of which represent early, mid and late plant immune response, respectively.

Finally, this study found that Stella Maris® inhibited the growth of multiple bacterial pathogens, including an opportunistic human pathogen that has demonstrated pathogenicity in plants. In summary, the pre-treatment with the seaweed extract protected Arabidopsis against subsequent infection by these pathogens.

The Ascophyllum nodosum extract, Stella Maris®, was found to modulate early-, mid- and late-immune responses in the model organism Arabidopsis. The extract not only directly inhibits the growth of all three bacterial pathogens tested, including an opportunistic human pathogen, it also activates a strong immune response in plants that had a protective effect against these bacterial pathogens.

This study suggests that seaweed extracts are effective biofertilizers due to the activation of the innate immune response in plants. Moving forward, seaweed extracts are an environmentally friendly option to enhance crop yield.

Stella Maris® was examined for its ability to sustain an immune response. The expression of PR-1, a defense gene regulated by SA production involved in systemic acquired resistance to attacking pathogens, was measured. The PR-1 gene expression was experimentally determined to be maximally induced by bacterial flagellin at the 24-h time point

The decrease in bacteria free-living within the MS media is likely due to the production of hydrogen peroxide and other antimicrobial compounds by the Arabidopsis seedlings, whereas the decrease in bacteria found within the plant tissue may be due to the strengthening of the plant cell wall.

It was important for the plant protection assay that the Stella Maris® be washed away prior to bacterial infection because the extract also has a noticeable inhibitory effect on bacterial growth.