natural-products-in-plant-pest-management

114 L.A. ShcherbakovaTable 5.1. Continued.Targetedplant pathogens Group of effective AMPM ReferenceSphaerotheca sp. Pseudopeptides Stein, 2005Uncinula nector Pseudopeptides Stein, 2005Ventura inaequalis Cyclopeptides Burr et al., 1996Phytophthora infestans Cyclopeptides De Bruijn et al., 2007Pythium intermedium Cyclopeptides De Souza et al., 2003Pythium ultimum Cyclopeptides Nielsen et al., 2002BacteriaErwinia amylovora Pseudopeptides Brady et al., 1999Jin et al., 2003Erwinia caratovora Cyclopeptides Selim, 2005Clavibacter michiganesis Peptaibols Xiao-Yan et al., 2006Pseudomonas syringae Cyclopeptides Bais et al., 2004Rhodococcus fascians Cyclopeptides Bassarello et al., 2004Antimicrobial peptides from plantsA broad family comprising antimicrobial peptides produced by plants iscalled defensins. One of their functions in plants is the involvement in defencemechanisms against pathogens, pests and abiotic stresses (Terras et al., 1995;Lay and Anderson, 2005). These are basic peptides structurally and functionallyrelated to the defensins of mammalia and insects. Molecular masses ofplant defensins that are characterized at present range from 5 to 7 kDa. Theirprimary structure is formed with 45–55 amino acid residues. Two structuralcharacteristics of the defensins, the presence of a pattern of conserved cysteineresidues and a domain with extremely variable amino acid sequence, aretypical components for mature peptide molecules of plant defensins. Withrare exceptions, defensins found in plants have a similar globular spatialstructure that is stabilized by a structural motif formed using disulfide bondsbetween eight cysteine residues. Possibly, defensins can aggregate in vivointo dimers or oligomers (Terras et al., 1992). A certain correlation is observedbetween the primary structure and antimicrobial activity of some plantdefensins. In general, the incorporation of basic amino acids (viz. arginine)that add positive charge to a peptide molecule resulted in a considerableincrease in the antimicrobial activity (Terras et al., 1992; De Samblanx et al.,1997; Landon et al., 2000).In the overwhelming majority of cases, plant defensins possess inhibitoryactivity against fungi; however, the growth of Gram-negative bacteria isalso arrested after exposure to these peptides (Terras et al., 1993; Segura et al,1998; Wong et al, 2006). An analysis of publications by Carvalho and Gomes(2009) showed many damaging plant pathogens of economically importantcrops can be inhibited in vitro with plant defensins. Various fungal species(Alternaria brassicola, Alternaria solani, Botrytis cinerea, Cladosporium colocasiae,