Bifurcaria bifurcata Aqueous Extract as Bio-Elicitors for Enhanced Resistance and Growth Promotion in Potato Plants Against Dickeya dadantii-Induced Soft Rot Disease

Phytopathogenic diseases are a major limiting factor in agricultural production. Therefore, scientific research continues to focus on developing effective techniques to mitigate their impact on crop productivity. Seaweed extracts, used as nutritional supplements, organic fertilizers, or bio-pesticides, have demonstrated their ability to enhance plant growth, increase yield, and alleviate the effects of abiotic stress. This study aimed to evaluate the effect of the aqueous extract of Bifurcaria bifurcata, collected from the Atlantic coast of Sidi Bouzid (El Jadida, Morocco), on the growth of Solanum tuberosum L., as well as its bactericidal activity against soft rot caused by Dickeya dadantii. The chemical Characterization revealed that Bifurcaria bifurcata aqueous extract is rich in polar and hydrophilic functional groups. In addition, this extract is particularly rich in phenolic metabolites, particularly phenolic acids, such as p-coumaric acid, ferulic acid, vanillic acid, and caffeic acid, which are known for their potential antimicrobial mechanisms. However, the treatment with 4 g/L extract resulted in a significant reduction in disease symptoms (>60%) and enhanced plant growth parameters, including 21% increase in plant height and 33% increase in leaf number. POX activity increased 6-fold (from 0.12 to 0.7 µmol/min/mg protein), indicating successful elicitation of plant defense mechanisms. The Bifurcaria bifurcata extract could act as novel activators of plant defense mechanisms and serve as potential alternatives to chemical pesticides.