Lectins and biocontrol

The harmful effects of chemical pesticides on the environment and human health have inspired a search for safer, environmentally-friendly control alternatives. The great advances in biotechnology, supported by basic studies utilizing molecular biology tools, have made biological control (i.e., the use of antagonistic microorganisms, fungi, or bacteria to reduce disease-producing activity and, consequently, crop loss) a potential nonhazardous alternative. An elucidation of the mechanisms underlying the biological control of plant pathogens could lead to the development of biocontrol agents with improved performance. In this respect, understanding the molecular basis for the recognition and specificity of the interaction between biocontrol agents and their hosts is fundamental. These crucial, early events, which influence and regulate the entire antagonistic process are mediated by sugar-binding proteins or glycoproteins, lectins, which are present on the cell surface. In some cases, lectins have been found to dictate the specificity of the interaction, discriminating host from non-host. In the present review, the significant role of lectins in the interaction between mycoparasitic biocontrol agents and their hosts is demonstrated in three different, albeit related, systems: parasite-nematode interactions and biotrophic and necrotrophic mycoparasites of plant pathogenic fungi.