Use of Alginate Extracted from Moroccan Brown Algae to Stimulate Natural Defense in Date Palm Roots.

Soukaina Bouissil,Zainab El Alaoui-Talibi,Guillaume Pierre,Philippe Michaud,Cherkaoui El Modafar,Cedric Delattre

doi:10.3390/molecules25030720

Abstract

Our study aimed to search for seaweed polysaccharides able to stimulate date palm defense mechanisms. Extraction, purification, characterization, and elicitor activity of sodium alginate (FSSA and BBSA) from Moroccan brown seaweeds Fucus spiralis and Bifurcaria bifurcata were investigated. FSSA and BBSA were characterized by proton nuclear magnetic resonance spectroscopy (1H-NMR) and size exclusion chromatography (HPLC-SEC). The mannuronic acid/guluronic acid (M/G) ratio of FSSA was M/G = 0.92 indicating that FSSA contained 48% and 52% of mannuronic and guluronic acids respectively, and the M/G ratio of BBSA was 0.47 indicating that BBSA contained 32% and 68% of mannuronic and guluronic acids respectively. Elicitor activity of FSSA and BBSA was carried out by developing an innovative study model on the date palm. The elicitor capacities were evaluated by investigating phenolic metabolism including phenylalanine ammonia-lyase (PAL) activity and total polyphenol content in seedling roots of date palm maintained in alginates solution (FSSA and BBSA) at different concentrations. The results obtained show that the PAL activity and the phenolic compound content were significantly stimulated with 1 mg·mL−1 of FSSA and BBSA; after 1 day of treatment with FSSA, and after 12 h of treatment with BBSA. These results show clearly those alginates extracted from Moroccan brown algae induced in date palm roots the stimulation of natural defense mechanisms.

Highlights

Researchers have given more and more consideration to natural polysaccharides thanks to their huge properties such as stability, biodegradability, and biocompatibility for food and therapeutics applications
Purification of the aqueous alkaline extracts from F. spiralis and B. bifurcata gave sodium alginate samples in 25 and 24% yield respectively based on dry weight
Extraction and characterization of alginates of two brown algae species harvested from the Moroccan coast was investigated as well as their elicitor capacity to induce natural defense in date palm roots

Summary

Introduction

Researchers have given more and more consideration to natural polysaccharides thanks to their huge properties such as stability, biodegradability, and biocompatibility for food and therapeutics applications. These considerable characteristics allow algal polysaccharides and their derivatives such as low molecular weight polymers and oligosaccharides structures to have great potential to be used in lots of domains such as agriculture (fertilizer, bio-elicitor, stimulators, signaling molecules, and activators). The search for new strategies ensuring sustainable protection of crops at lower ecological cost is essential, given the environmental and health challenges related to the increased use of chemical pesticides, in order to meet these environmental and societal requirements in terms of phytoprotection, stimulating the natural defenses of plants represents a promising approach in Molecules 2020, 25, 720; doi:10.3390/molecules25030720 www.mdpi.com/journal/molecules. We noted that the plant had the capacity to perceive and decode an external signal which, in turn, triggered a whole series of events leading to the coordinated synthesis and to the sequential accumulation of defense molecules

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