Lectins : important tools for biocontrol of Fusarium species

Abstract

Lectins are proteins from non-immune origin, containing two or more binding sites to mono or oligosaccharides. Plant lectins, found in different plant tissues, show a marked heterogeneity with respect to their molecular structure and sugar-binding specificity. Fungi are frequently pathogens of cultivated plant species representing one of the main causes of crop losses. Growth of fungi has been considered a major factor in biodeterioration of materials such as wood, stored grains, paintings, sculptures, leather, and oil. Fusarium is a filamentous fungi genus widely distributed in soil and in association with plants. Fusarium is a pathogen of bananas, corn, rice, wheat, tomatoes, peanuts, among other crops. Some Fusarium species produce mycotoxins that have been found infecting breakfast and infant cereals. Fusarium species can affect human health causing cutaneous infections and keratitis, for example. The intensive use of synthetic fungicides for plant disease control is cause of public concern because of the presence of residues in water and crops for animal and human consumption. Biodegradable fungicides derived from plants have been searched aiming to minimize environmental damage. Antifungal effects on Fusarium species have been reported for lectins isolated from different plant tissues. The role of lectins in fungi plant defense mechanisms may have evolved from its ability to recognize and agglutinate cells or glycoconjugates in sites for potential invasion by infectious agents, with ability to inhibit fungal growth and germination. Antifungal activity has been reported mainly for chitin-binding lectins which are able to bind chitin present in fungal cell wall and interfere in spore germination. In summary, this chapter discusses the optimistic perspectives for lectin preparations that can be applied in agriculture as cheap and biodegradable antifungal agents preventing pollution of the environment without damages to the biodiversity.