Development of Diagnostic Methods for Detecting Ganoderma‐infected Oil Palms

Two diagnostic methods have been applied for detecting the plant pathogenic fungus Ganoderma, a basidiomycete, causing the basal stem rot (BSR) diseaseof oil palms. One approach was the use of polyclonal antibodies (PAbs) raised against mycelial proteins of a single Ganoderma isolate and a mixture of nine different Ganoderma isolates. Both PAbs could detect Ganoderma in diseased oil palm root tissue by applying an indirect enzyme‐linked immunosorbent assay. Low cross‐reactions were observed with the five mainly occurring saprophytic fungi which could be isolated from diseased oil palms and were used as negative controls. The other approach was based on the polymerase chain reaction (PCR) in order to increase the sensitivity of the Ganoderma detection. The primers were generated from the internal transcribed spacer region 1 of rDNA of Ganoderma boninense and produced an PCR product of 167 bp in size. Fungal isolates and oil palm root samples were processed for PCR by three different DNA extraction methods. The most suitable extraction procedure was a simple alkaline extraction method. For a practical approach, a semiquantification was performed by assessing the PCR sensitivity limits of pure culture Ganoderma and naturally infected root samples.