Emulsions of essential oils and aloe polysaccharides: Antimicrobial activity and resistance inducer potential against Xanthomonas fragariae

Abstract

Bacterial angular leaf spot disease (Xanthomonas fragariae) is an important strawberry disease and responsible for significant yield losses. The efficacy of emulsions containing tea tree or palmarosa essential oils (EO) against angular leaf spot, seeking to elucidate their mode of action, was evaluated in this study. Tea tree or palmarosa EO were added in an aqueous suspension of aloe polysaccharide (AP) and tea tree EO emulsion (TAP) and palmarosa EO microemulsion (PAP) were obtained. The antimicrobial potential of AP, TAP and PAP were evaluated in plants of two cultivars (Albion and San Andreas). The ability of these preparations to reduce disease severity and to activate plant defenses were evaluated. AP, TAP and PAP reduced X. fragariae growth by up to 44.0%, 94.4% and 86.1%, respectively. In addition, T AP and P AP suppressed completely the symptoms in both cultivars. Increased activities of superoxide dismutase, dismutase, catalase and peroxidase were observed in the more susceptible cultivar (Albion) treated with the emulsions, while a higher concentration of total phenolic compounds was verified in the less susceptible cultivar (San Andreas). Thus, emulsions with EO and AP can be used to control angular leaf spot by activating latent defense mechanisms in strawberry.

Aloe Genus Plants: From Farm to Food Applications and Phytopharmacotherapy

“…They found that from all of the tested alcoholic and aqueous extracts, A. vera showed the strongest activity against E. coli and S. aureus . What is more, aloe polysaccharides were used in tea tree or palmarosa essential oil combinations as a natural strategy against Xanthomonas fragariae (bacterial angular leaf spot disease, which is an important strawberry disease responsible for significant yield losses) [ 138 ]. It was found that these preparations reduce disease severity and activate plant defenses, and that Aloe polysaccharides alone reduced X. fragariae growth by up to 44%.…”

Extraction, Purification, Structural Characteristics, Biological Activities and Pharmacological Applications of Acemannan, a Polysaccharide from Aloe vera: A Review

“…Polysaccharides are a kind of carbohydrate with high molecular weight, which represent a major class of bioactive molecules derived from microorganisms, animals, or plants [1]. Polysaccharides are extensively used in various healthcare products and medicines because of their notable and excellent bioactivities, such as antimicrobial [2], antitumor [3], antiviral [4], and antioxidant activities [5]. In addition, polysaccharides are among the natural biopolymers found on Earth [6], which are widely used as biomaterials for wound healing [7], drug delivery [8] and tissue engineering [9].…”

Phytochemical Composition, Antioxidant, Antibacterial, and Enzyme Inhibitory Activities of Various Organic Extracts from Apocynum hendersonii (Hook.f.) Woodson

“…Polysaccharides are monosaccharides polymers joined by glycosidic bonds. They are reported to have antioxidant, antibacterial, antiviral, and antitumor properties, making them essential products in the pharmaceutical, food, and feed as well as cosmetic industries [ 34 , 35 , 36 , 37 ]. The polysaccharide content obtained from the various extracts is presented in Figure 2 A.…”