natural-products-in-plant-pest-management

112 L.A. Shcherbakovainteract with pathogenic microflora or induce resistance in plants. Constitutiveor inducible expression of protein-encoding genes transferred into plantsconfer them resistance to many economically important diseases.Several groups of microbial and plant proteinaceous substances thathave well-established potentialities in plant protection will be very brieflyreviewed below. The antipathogenic properties of two proteins, which wereisolated from biocontrol bacteria and relatively recently studied as putativeelicitors of disease resistance in plants, will be described in more detail.The biocontrol potential of proteinaceous compounds will be consideredalmost exclusively by using examples of fungal and bacterial pathogens.Their antipest properties will be not covered within the scope of this chapter.Nevertheless, it should be emphasized that many proteins and peptides discussedin this section (microbial peptides, defensins, proteinase inhibitorsand lectins) are well known as biological insecticides or nematicides of greatpotentiality. Biopesticides based on microbial peptides or transgenic plantscarrying genes of defensins, lectins and proteinase inhibitors are good toolsfor the fight against pests of plants.Antimicrobial peptides produced by microorganisms and plantsThe generation of antimicrobial peptides is one of the widespread naturaldefence mechanisms of innate immunity of living organisms, and these compoundsare interesting targets for green consumerization. Plants, includingagricultural crops, produce numerous defensive peptides. Microorganisms,including those used in plant protection, synthesize and excrete antimicrobialpeptides that are often responsible for the biocontrol effect. In severalauthors’ opinions, peptides have advantages over more elementary organicantimicrobial compounds when used for plant protection goals. Because thepeptide molecules contain from 10 to 50 (sometimes up to 85) amino acidresidues, they can more specifically interact with their protein targets incausative agents (Park et al., 2009). Biopesticidal peptides can work againstpathogens by inhibiting nucleic-acid and protein biosyntheses and enzymeactivity or by interacting with the plasmalemma and destroying its integrity(Huang, 2000).Antimicrobial peptides from biocontrol microorganismsPeptides possessing antimicrobial effects have been reported to be producedby bacteria, fungi, plants, invertebrates and vertebrates (Garcia-Olmedo et al., 1998; Zasloff, 2002; Degenkolb et al., 2003; Bulet et al., 2004;Nybroe and Sorensen, 2004; Carvalho and Gomes, 2009). According to therecent review focused on antimicrobial peptides related to plant-diseasecontrol (Montesinos, 2007), about 900 antimicrobial peptides are producedby living organisms via ribosomal or non-ribosomal synthesis. Biocontrolmicroorganisms have been reported to use both types of the peptide synthesis(Finking and Marahiel, 2004; Montesinos, 2007) and generate a widerange of these compounds. Antimicrobial peptides of microorganisms