Biostimulant activity of chitosan in horticulture

Among alternatives that are currently under investigation to replace the use of synthetic fungicides to control postharvest diseases in fresh produce and to extend their shelf life, chitosan application has shown promising disease control, at both preharvest and postharvest stages. Chitosan shows a dual mode of action, on the pathogen and on the plant, as it reduces the growth of decay-causing fungi and foodborne pathogens and induces resistance responses in the host tissues. Chitosan coating forms a semipermeable film on the surface of fruit and vegetables, thereby delaying the rate of respiration, decreasing weight loss, maintaining the overall quality, and prolonging the shelf life. Moreover, the coating can provide a substrate for incorporation of other functional food additives, such as minerals, vitamins, or other drugs or nutraceutical compounds that can be used to enhance the beneficial properties of fresh commodities, or in some cases the antimicrobial activity of chitosan. Chitosan coating has been approved as GRAS substance by USFDA, and its application is safe for the consumer and the environment. This review summarizes the most relevant and recent knowledge in the application of chitosan in postharvest disease control and maintenance of overall fruit and vegetable quality during postharvest storage.

Shelf life extension of fresh fruit and vegetables by chitosan treatment.

Efficacy of the application of a coating composed of chitosan and Origanum vulgare L. essential oil to control Rhizopus stolonifer and Aspergillus niger in grapes (Vitis labrusca L.)

Chitosan and its oligosaccharides, a promising option for sustainable crop production- a review

Efficacy of the combined application of chitosan and Locust Bean Gum with different citrus essential oils to control postharvest spoilage caused by Aspergillus flavus in dates.

Antifungal activity of chitosan on Fusarium sulphureum in relation to dry rot of potato tuber.

Postharvest Chitosan Treatment Induces Resistance in Potato Against Fusarium sulphureum

A glycoprotein from mountain cultivated ginseng: Insights into their chemical characteristics and intracellular antioxidant activity.

The defensive-offensive associations between algae and herbivores determine marine ecology. Brown algae utilize phlorotannin as their chemical defense against the predator Aplysia kurodai, which uses β-glucosidase (akuBGL) to digest the laminarin in algae to glucose. Moreover, A. kurodai employs Eisenia hydrolysis-enhancing protein (EHEP) as an offense to protect akuBGL activity from phlorotannin inhibition by precipitating phlorotannin. To underpin the molecular mechanism of this digestive-defensive-offensive system, we determined the structures of apo and tannic-acid (TNA, a phlorotannin-analog) bound form of EHEP, as well as akuBGL. EHEP consisted of three peritrophin-A domains formed in a triangle and bound TNA in the center without significant conformational changes. Structural comparison between EHEP and EHEP– TNA led us to find that EHEP can be resolubilized from phlorotannin-precipitation at an alkaline pH, which reflects a requirement in the digestive tract. akuBGL contained two GH1 domains, only one of which conserved the active site. Combining docking analysis, we propose the mechanisms by which phlorotannin inhibits akuBGL by occupying the substrate-binding pocket, and EHEP protects akuBGL against the inhibition by binding with phlorotannin to free the akuBGL pocket.

/pdf/structural-basis-of-ehep-mediated-offense-against-3byt2zo2.pdf

Xiao-juan Sun

Papers

Antifungal activity of chitosan on Fusarium sulphureum in relation to dry rot of potato tuber.

Postharvest Chitosan Treatment Induces Resistance in Potato Against Fusarium sulphureum

A glycoprotein from mountain cultivated ginseng: Insights into their chemical characteristics and intracellular antioxidant activity.

Structural basis of EHEP-mediated offense against phlorotannin-induced defense from brown algae to protect akuBGL activity