Detection and quantification of individual fungal species in disease complexes by polymerase chain reaction (PCR)

Until recently, no method was available to identify and quantify individual fungal species present within plant tissue. Specific DNA markers have been identified for the majority of the components of the 'stem-base complex' and 'ear blight complex' which are two disease complexes affecting cereals. Assays based upon the polymerase chain reaction (PCR) have been developed for detection of these fungi directly in extracts from plant tissue. These assays have been refined to enable quantification of each species, allowing the relative contribution of each component to the disease of the plant to be estimated. Detection and quantification of F. poae and other Fusarium species in samples of wheat seed is reported as an example of the use of these PCR techniques. Some potential uses for these systems are discussed.