Immunological detection of syrirngopeptins produced by Pseudomonas syringae pv. lachrymans

Several strains of plant pathogenic Pseudomonas are known to produce phytot oxic lipodepsipeptides (syringomycin, syringopeptins and related compounds) in vitro. However, detection of these compounds in organic extracts from d iseased plant tissues has been. attempted by chromatographic methods for sy ringomycin only. A macromolecular derivative of syringopeptins (KLH-SP25A+B ) was used to raise polyclonal antibodies in rabbit. The antiserum was able to recognize free syringopeptins (SP22 and SP25) with an estimated detecti on limit of 0.05 mu g per well in the indirect ELISA, and 0.01 mu g per wel l in the competitive ELISA. Cross-reaction with other structurally related lipodepsipeptides, e.g. syringomycins and pseudomycin A, was less than 20%. Using the competitive ELISA method developed in this study, relatively abu ndant quantities of the toxins, i.e. approximately; 0.1 mg of syringopeptin s per gram fresh tissue, were detected when an aqueous extract from cotyled ons of zucchini infected with a strain of P. syringae pv. lachrymans was te sted. (C) 1999 Academic Press.