Seaweed polysaccharides as bio-elicitors of natural defenses in olive trees against verticillium wilt of olive

Abstract

Ulvan, carrageenan, alginate and laminarin were tested in olive trees' twigs to elicit phenolic metabolism and control verticillium wilt of olive (VWO) caused by Verticillium dahliae. The elicitation effect was determined through phenylalanine ammonia-lyase activity, total polyphenol content and lignin content. VWO was assessed in twigs previously elicited (24 h) and maintained in a solution containing bio-elicitors (2 g/L) and conidial suspension (10 6 conidia/mL). Our results showed stimulation of the phenolic metabolism and the decline of wilt symptoms. Ulvan reduced significantly the area under the disease progress curve for severity to 39.9% and the final incidence to 28.9%. Ulvan and alginate produced significant inhibitory rates on mycelial growth of the fungus in vitro. Seaweed polysaccharides might help to overcome VWO by strengthening the host defense metabolism and restricting the pathogen's growth.

Phenolic composition of Tempranillo Blanco (Vitis vinifera L.) grapes and wines after biostimulation via a foliar seaweed application

“…Additionally, anthocyanidin reductase (AR) involves the conversion of cyanidin into catechin . Seaweed contains a wide range of polysaccharides that can act as elicitors in horticulture . Horbowicz et al .…”

“…Elicitor activity is associated with polysaccharide fraction of the seaweed elaborated extracts . Polysaccharides purified from seaweeds, as well as derived oligosaccharides, have the ability to trigger plant defense responses . To our knowledge, there is little information available in the literature concerning the effects of seaweed application to grapevines.…”

“…34 Seaweed contains a wide range of polysaccharides that can act as elicitors in horticulture. 19 Horbowicz et al 35 suggested that methyl jasmonate (an abiotic elicitor) probably increases the activity of the leucocyanidin reductase or anthocyanidin reductase in seedlings of common buckwheat (Fagopyrum esculentum). Accordingly, it is probable that seaweed application to grapevines at high dosage might trigger the activation of LAR or AR enzymes, inducing the synthesis of catechin in grapes.…”

“…Different studies suggest that seaweed extracts can behave as novel elicitors, triggering the accumulation of secondary metabolites, mainly phenolic compounds in several plant crops, including grapevines . However, most studies concerning the effects of seaweed application on grapevines focus on its effects on plant physiology, productivity and some secondary metabolism of grapes or musts than on grape and wine quality in terms of phenolic composition .…”

“…16 Different studies suggest that seaweed extracts can behave as novel elicitors, triggering the accumulation of secondary metabolites, mainly phenolic compounds in several plant crops, including grapevines. [17][18][19][20] However, most studies concerning the effects of seaweed application on grapevines focus on its effects on plant physiology, productivity and some secondary metabolism of grapes or musts than on grape and wine quality in terms of phenolic composition. [20][21][22][23] Accordingly, the present study aimed to (i) characterize Tempranillo Blanco grape and wine phenolic composition and (ii) investigate the effect of foliar application of an Ascophyllum nodosum seaweed fertilizer to Tempranillo Blanco grapevines, at two different dosages, on grape and wine phenolic composition during two consecutive seasons (2017-2018).…”