Immunodetection of elicitins from <i>Phytophthora</i> spp. using monoclonal antibodies

Abstract

Ten monoclonal antibodies were selected from mice immunized with a highly purified elicitin secreted by Phytophthora cryptogea , termed cryptogein. These antibodies could be classified into five groups according to their cross‐reactivity to heterologous elicitins from other Phytophthora species, from strict specificity (reacting solely with cryptogein) to broad reactivity (reacting with all four elicitins under study). When examined on BIA core (a real‐time biospecific interaction analyser), these monoclonal antibodies were found to recognize at least three different epitopes on the cryptogein molecule. Their use in elicitin detection and quantification was optimized in several ELISA protocols. A mixed monoclonal‐polyclonal antibody, indirect DAS‐ELISA procedure detected as little as 20 pg of purified elicitin per well (100 μl). The four elicitins could be detected with the aid of one of couple of polyvalent reagents, whilst each one could be detected separately using appropriate monoclonal antibodies. These protocols have been used to detect elicitins secreted by Phytophthora spp. into culture medium as well as in planta following plant inoculation.