ABSTRACT
The need to reduce fungicide use in agriculture has increased the interest in antimicrobial peptides (AMPs) specific for phytopathogenic fungi. AMPs have also been proposed as alternatives during postharvest conservation, alone or in conjunction with integrated management strategies. AMPs are widespread in nature and evolutionary conserved. Small cysteine-rich proteins (CRPs) such as plant defensins and antifungal proteins produced by filamentous fungi are a major group of AMPs. The current knowledge about these biomolecules will be reviewed around three major areas: the latest findings on the identification and rational design of antifungal peptides and proteins with improved activity, stability, and specificity; the characterization of their modes of action; and the approaches for their use to prevent decay during fruit postharvest conservation. Non-lytic modes of action have been reported for an increasing number of antifungal peptides and proteins and are linked to low toxicity against non-target organisms, a desirable property for any antimicrobial drug. These non-lytic mechanisms include specific cell binding, non-disruptive cell internalization similar to cell penetrating peptides, and intracellular killing. Knowledge of these mechanisms is expected to greatly impact the discovery and rational design of novel peptides and, even more importantly, the identification of novel antifungal cell targets. The commercial use of these molecules is hampered by the difficulties in their production. The decreasing cost of synthetic procedures in conjunction with the discovery of minimal antifungal motifs, as well as the development of biotechnological production systems, both in situ and in cell factories, will offer solutions for their commercial application.
