An Ulva armoricana extract protects plants against three powdery mildew pathogens

Abstract

The protective activity of a crude extract prepared from the green macroalga, Ulva armoricana, previously shown to induce plant defence responses, was evaluated on three plant species, common bean, grapevine and cucumber, cultivated in the greenhouse and inoculated with three powdery mildew pathogens Erysiphe polygoni, E. necator and Sphareotheca fuliginea respectively. Chemical analyses showed that the extract was enriched in ulvans, which are green algae polysaccharides essentially composed of uronic acid and sulphated rhamnose. Weekly applications were performed by spraying of the green algal extract at various dilutions on bean, grapevine and cucumber leaves. A significant effect (50% protection) was observed using a dilution corresponding to about 3 gl −1 dry matter and up to 90% reduction of symptom severity was obtained for the highest concentration (1/9 dilution, 6 gl −1 dry matter) for the three plant species. To study the natural variability of the protective activity, five extracts prepared from algae batches harvested at different year periods were evaluated. Although polysaccharide composition varied among batches, all extracts elicit a reporter gene regulated by a defence-gene promoter in a transgenic tobacco line, and protect cucumber plants against powdery mildew infection. Together, these data demonstrate that U. armoricana is a reproducible source of active compounds which can be used to efficiently protect crop plants against powdery mildew diseases.

Algal polysaccharides as source of plant resistance inducers

“…As the result, Ulva fasciata Delile was identified as a potential source to provide active compounds for the control of foliar diseases, such as powdery mildew (Erysiphe polygoni DeCandolle) and anthracnose (Colletotrichum lindemuthianum Saccardo and Magnus) on bean (Loffaguen et al, 2004;Abreu, 2005;Abreu et al, 2008). Under greenhouse conditions, spraying of beans with extract of Ulva led to a strong reduction (almost 80%) in the number of powdery mildew (E. poligoni) colonies on pre-treated leaves (Jaulneau et al 2011).…”

“…and can reduce the severity of a broad range of diseases on beans, such as rust (Uromyces appendiculatus (Persoon) Link) (Borsato et al, 2010;Delgado et al, 2013), anthracnose (C. lindemuthianum) (Paulert et al, 2009;Freitas & Stadnik, 2012) and powdery mildew (E. poligoni) (Jaulneau et al, 2011). In addition, the polissaccharide has shown promising results against other diseases such as Glomerella leaf spot (C. gloeosporioides (Penzig) Penzig and Saccardo) on apple (Araújo et al, 2008;Araújo & Stadnik, 2013) and powdery mildew (Blumeria graminis (DeCandole) Speer) on wheat and barley (Paulert et al, 2010;Jaulneau et al, 2011). The effects of ulvan in different pathosystems are shown on Table 1.…”

Production of sulfated oligosaccharides from the seaweed Ulva sp. using a new ulvan-degrading enzymatic bacterial crude extract

“…Three pH buffer conditions (6, 7 and 8) were first assayed for degradation rate at 35°C and the kinetics of the reaction were followed by analyzing the evolution of the area under the curve of each TLC peak. The pH condition with the highest degradation rate was used to assay the degradation rate at four different temperatures (20,25,30, 35°C) (n = 3).…”

“…Its molecular weight depends on the algal species and the extraction protocol; however it is generally high and can round up to 700-800 kDa [7]. This glycosaminoglycan-like structure has anticoagulant [8], antioxidant [9][10][11], immunomodulator [12,13], antihypercholesterolemic [14], antihyperlipidemic [15,16], antiviral [17], antitumoral [18,19] and plant defense elicitor activities [20][21][22][23]. It has been used in forming biomaterials such as nanofibers, nanofibrous membrane [24,25], microparticles [26], molecular sponges for cell culture [27], antiadhesive activity [28] or as ion exchanger hydrogel [29].…”

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

“…Ulva extract protect Medicago truncatula plants against infection by Colletotrichum trifolii (Cluzet et al 2004), Phaseolus vulgaris against infection by Colletotrichum lindemuthianum (Paulert et al 2009), bean, grapevine and cucumber against powdery mildew (Jaulneau et al 2011), and cucumber against a range of fungal infections (Jayaraman et al 2011;Abkhoo and Sabbagh 2015). Different components of seaweed extract work synergistically at different concentrations making its application beneficial, although the mode of action still remains unknown (Fornes et al 2002).…”