Algal polysaccharides as source of plant resistance inducers

Abstract

Algal compounds exhibit great potential to enhance plant growth and resistance to abiotic and biotic stresses. This review focuses on aspects concerning the physical-chemical properties, function and biological activity of macroalgae polysaccharides. Updated results of the main poly-and oligosaccharides studied for the control of plant diseases are discussed and summarized. The carrageenans from red algae have a well-established obtaining system, but its high market value discourages its use in plant protection. The fucans found in the cell walls of brown algae are present in several fertilizers and accounted for the benefits of such commercial products on plant physiology. The laminarans, from brown algae mainly Laminaria digitata, are currently the main algal polysaccharides on the phytosanitary market. The ulvans, from cell the walls of Ulva spp., open new ways to obtain polysaccharides able to induce resistance due to its abundance worldwide. All these algal polysaccharides show ability to activate multiple plant defense mechanisms against a broad spectrum of plant pathogens. Taking into account the promising results reported in the literature and the enormous biochemical diversity of these biopolymers, it is likely that they will provide new types of resistance inducers in a near future.

Ulvans induce resistance against plant pathogenic fungi independently of their sulfation degree

“…Among them, carbohydrates are probably the most abundant organic compounds in the oceans with a great molecular diversity (Alves, Sousa, & Reis, 2013;Khan et al, 2009;Sharma, Fleming, Selby, Rao, & Martin, 2014;Stadnik & de Freitas, 2014). Ulvans are water-soluble sulfated heteropolysaccharides extracted from the cell walls of the green macroalgae Ulva spp.…”

“…Ulvans are water-soluble sulfated heteropolysaccharides extracted from the cell walls of the green macroalgae Ulva spp. They have been one of the most studied algal carbohydrates with potential application in several areas, including agriculture (Alves et al, 2013;Stadnik & de Freitas, 2014).…”

“…These sulfated polysaccharides are structurally constituted by two main repeating disaccharides, the ulvanobiuronic acid type A [→4)-␤-d-GlcA-(1 → 4)-␣-l-Rha 3S-(1 → ] and type B [→4)-␣-LIdoA-(1 → 4)-␣-l-Rha 3S-(1 → ] (Alves et al, 2013;Lahaye & Robic, 2007;Stadnik & de Freitas, 2014). Ulvans are known to exhibit different biological activities in the pharmaceutical and biomedical context (Alves et al, 2013).…”

“…Ulvans are known to exhibit different biological activities in the pharmaceutical and biomedical context (Alves et al, 2013). In crop sciences, studies have revealed that they can be applied to stimulate growth and defense of plants (Alves et al, 2013;Stadnik & de Freitas, 2014).…”

Insights into the role of seaweed Kappaphycus alvarezii sap towards phytohormone signalling and regulating defence responsive genes in Lycopersicon esculentum

“…It was realized that the liquid sap obtained by the mechanical crushing of the fresh seaweed is a potent biostimulant for various crops upon its foliar application and the residue obtained after the recovery of the sap is a rich source of kappa-carrageenan, a biopolymer used commercially as thickener in milk, beverage and other industries (Eswaran et al 2006). Furthermore, Stadnik and de Freitas (2014) have reviewed the role of algal polysaccharides including carrageenans with respect to plant defense mechanisms. The carrageenans and their oligosaccharides are known to induce resistance in plants against bacteria, fungi and virus (Vera et al 2012).…”