Synergistic Antimicrobial Activities of Chitosan Mixtures and Chitosan–Copper Combinations

Abstract

Several recent studies revealed the significant contribution of intensive agriculture to global climate change and biodiversity decline. However, synthetic pesticides and fertilizers, which are among the main reasons for these negative effects, are required to achieve the high performance of elite crops needed to feed the growing world population. Modern agro-biologics, such as biopesticides, biostimulants, and biofertilizers are intended to replace or reduce the current agro-chemicals, but the former are often difficult to combine with the latter. Chitosans, produced from the fisheries’ byproduct chitin, are among the most promising agro-biologics, and copper fungicides are among the most widely used plant protectants in organic farming. However, the two active ingredients tend to form precipitates, hindering product development. Here, we show that partial hydrolysis of a chitosan polymer can yield a mixture of smaller polymers and oligomers that act synergistically in their antifungal activity. The low molecular weight (Mw) of this hydrolysate allows its combination with copper acetate, again leading to a synergistic effect. Combined, these synergies allow a 50% reduction in copper concentration, while maintaining the antifungal activity. This is potentially a significant step towards a more sustainable agriculture.

Arabidopsis immune responses triggered by cellulose‐ and mixed‐linked glucan‐derived oligosaccharides require a group ofleucine‐rich repeat malectinreceptor kinases

“…The exogenous application of glycans enhanced disease resistance of different plant species to diverse pathogens, acknowledging the relevance of these carbohydrate‐based ligands released during plant–microbe interaction in the regulation of plant disease resistance (Mélida et al., 2018; Rebaque et al., 2021). This oligosaccharide‐mediated priming effect on PTI and disease resistance has driven the development of sustainable crop protection solutions based on combinations of active glycans (DAMPs and MAMPs; Chaliha et al., 2020, Lemke et al., 2022). The discovery of counterpart receptors for these active glycans in crops would accelerate the selection of the corresponding genes in breeding programs to enhance crop disease resistance.…”

Arabidopsis Leucine Rich Repeat-Malectin Receptor Kinases in immunity triggered by cellulose and mixed-linked glucan oligosaccharides

“…We then performed in silico analyses on the predicted AlphaFold LRR-MAL RLK model structures to understand the impact of igp1 and igp2/igp3 point mutations in the KD of AT1G56130 and AT1G56145. AlphaFold predicts LRR, MAL and KD domains of the three RLKs with confidence very high (> 90%) for LRR and KD, high for MAL (70–90) and low (50-70%) or very low (< 50%) for transmembrane (TM) and both N- and C-terminal regions, respectively ( SI Appendix , Fig. S11A-C).…”

“…The relevance of these carbohydrate-based ligands released during plant-microbe interaction in the regulation of plant disease resistance has been proved in different plant species that show enhanced disease resistance to different pathogens upon exogenous application of glycans DAMPs/MAMPs (e.g., MLG43) in comparison to untreated plants (15, 31). This oligosaccharide-mediated priming effect on PTI and disease resistance has driven the development of sustainable crop protection solutions based on mixtures of active glycans (DAMPs/MAMPs: (69, 70)). The discovery of counterpart receptors for these active glycans in crops will accelerate the selection of the corresponding genes in breeding programs to enhance crops disease resistance.…”

The Antifungal Properties of Tamarix aphylla Extract against Some Plant Pathogenic Fungi

“…), which causes an increase or loss in their original biological activity. Furthermore, the substances in the extracts may act as elicitors of resistance through different mechanisms mediated by the host tissue [ 49 , 50 ].…”