IN-VITRO CHARACTERIZATION AND IN-VIVO DETECTION OF RIGIDOPORUS-LIGNOSUS, THE CAUSAL AGENT OF WHITE ROOT DISEASE IN HEVEA-BRASILIENSIS, BY ELISA TECHNIQUES

The aim of these studies is to develop a method for early detection of Rigidoporus lignosus (Basidiomycete, Polyporaceae), the causative age nt of white root disease of rubber tree. Two polyclonal sera were prod uced against soluble mycelial proteins of two R. lignosus isolates, on e from Africa (FCI2), the other from Asia (FID2). The specificity of t he antisera was tested using isoelectric focusing (IEF)/Western-blot a nd DAS-ELISA. The two sera recognized all 20 R. lignosus isolates from various geographical origins. The banding patterns obtained by Wester n-blot enabled a distinction to be made between isolates from Africa a nd those from Asia. In DAS-ELISA and Western-blot analyses, strong cro ss reactions were observed with R. ulmarius. Only slight reactions wer e observed in Western-blot analysis to R. lineatus and P. noxius, both causative agents of root rot in Hevea. These cross reactions were not observed under our DAS-ELISA analysis conditions. Finally, no cross r eactions were obtained with 9 other Polyporaceae or Hevea root pathoge n species. The sensitivity threshold of the DAS-ELISA method was 5 ng ml(-1) of R. lignosus protein. An initial approach to using the DAS-EL ISA test for the detection of R. lignosus in infected plants was carri ed out on artificially inoculated root samples. The DAS-ELISA protocol enabled detection of R. lignosus in the root systems of diseased plan ts. Moreover, no cross reaction was observed with healthy plant extrac ts.