Use of Defensins to Develop Eco-Friendly Alternatives to Synthetic Fungicides to Control Phytopathogenic Fungi and Their Mycotoxins

Abstract

Crops are threatened by numerous fungal diseases that can adversely affect the availability and quality of agricultural commodities. In addition, some of these fungal phytopathogens have the capacity to produce mycotoxins that pose a serious health threat to humans and livestock. To facilitate the transition towards sustainable environmentally friendly agriculture, there is an urgent need to develop innovative methods allowing a reduced use of synthetic fungicides while guaranteeing optimal yields and the safety of the harvests. Several defensins have been reported to display antifungal and even—despite being under-studied—antimycotoxin activities and could be promising natural molecules for the development of control strategies. This review analyses pioneering and recent work addressing the bioactivity of defensins towards fungal phytopathogens; the details of approximately 100 active defensins and defensin-like peptides occurring in plants, mammals, fungi and invertebrates are listed. Moreover, the multi-faceted mechanism of action employed by defensins, the opportunity to optimize large-scale production procedures such as their solubility, stability and toxicity to plants and mammals are discussed. Overall, the knowledge gathered within the present review strongly supports the bright future held by defensin-based plant protection solutions while pointing out the obstacles that still need to be overcome to translate defensin-based in vitro research findings into commercial products.

Plant defensin MtDef4‐derived antifungal peptide with multiple modes of action and potential as a bio‐inspired fungicide

“…Defensins, in particular, are one of the largest families of AMPs expressed in plants. Because of their potent antifungal activity, diverse amino acid sequences, and multitarget modes of action (MoA), plant defensins have emerged as potential antifungal agents for agriculture (Cools et al, 2017; Leannec‐Rialland et al, 2022; Parisi et al, 2019). Plant defensins are 45‐ to 54‐amino‐acid, cysteine‐rich, cationic peptides characterized by the presence of a cysteine‐stabilized αβ motif.…”

“…The fourth disulphide bond connects near the N‐ and C‐termini and essentially cyclizes the peptide (Kovaleva et al, 2020). The cationic plant defensins exhibit potent broad‐spectrum antifungal activity against fungal pathogens in vitro and in planta (Kaur et al, 2011; Kovaleva et al, 2020; Lacerda et al, 2014; Leannec‐Rialland et al, 2022). We set out to investigate if truncated plant defensins containing the active C‐terminal γ‐core motif (GXCX 3‐9 C) exhibit potent fungicidal activity and are effective as spray‐on fungicides for management of fungal diseases.…”

Plant defensin MtDef4-derived antifungal peptide with multiple modes of action and potential as a bioinspired fungicide

“…Defensins, in particular, are one of the largest families of AMPs expressed in plants. Because of their potent antifungal activity, diverse amino acid sequences, and multi-target MoA, plant defensins have emerged as potential antifungal agents for agriculture (Cools et al ., 2017, Parisi et al ., 2019, Leannec-Rialland et al ., 2022). Plant defensins are 45-54 amino acids long, cysteine-rich, cationic peptides characterized by the presence of a cysteine-stabilized αβ motif.…”

“…The fourth disulfide bond connects near the N-and C-termini and essentially cyclizes the peptide (Kovaleva et al ., 2020). The cationic plant defensins exhibit potent broad-spectrum antifungal activity against fungal pathogens in vitro and in planta (Kaur et al ., 2011, Kovaleva et al, 2020, Lacerda et al ., 2014, Leannec-Rialland et al, 2022). We set out to investigate if truncated plant defensins containing the active carboxy-terminal γ-core motif (GXCX3-9C) exhibited potent fungicidal activity and were effective as spray-on fungicides for management of fungal diseases.…”

Estudio de defensinas de flores de cardos con potencial aplicación biotecnológica

“…La aplicación de fungicidas de origen sintético ha sido la principal estrategia adoptada por los productores agropecuarios y es utilizada en la actualidad para combatir las enfermedades causadas por hongos en cultivos. Sin embargo, la preocupación relativa a la contaminación ambiental, los riesgos para la salud humana así como las restricciones de uso en varios países pone de manifiesto la necesidad de buscar nuevos agentes antifúngicos más seguros y eficaces (Leannec-Rialland et al, 2022). Ha sido documentada la efectividad de la sobreexpresión de defensinas en plantas, mejorando significativamente la resistencia frente a varios patógenos fúngicos, tanto en ensayos en invernadero como en ensayos de campo, siendo mayores los reportes del primer tipo de ensayos (J.…”