Identification of arbuscular mycorrhizal fungi from Artemisia californica using the polymerase chain reaction

The obligately symbiotic group of fungi, the arbuscular mycorrhizal (AM) fungi possess several characteristics that make identification, and therefore ecological field studies, difficult. A major limitation is that this group cannot be grown in pure culture. Traditional methods of identifying this group rely on the isolation of asexual spores from the soil. These spores, which are resting structures, do not necessarily reflect what species is actively colonizing the plant root. We have recently utilized molecular methods to develop a protocol for identifying AM fungi. Field collected spores were identified using traditional microscopy, and the DNA extracted for amplification. A DNA extraction method using crude lysate was developed which eliminates the need for a large amount of tissue and produces a DNA template suitable for PCR amplification. Results indicate that size polymorphisms in the ITS region of rDNA can distinguish between genera, and can be used to screen species. Amplification products of field collected Artemisia californica roots showed that these fungal endophytes may be identified to species based on size polymorphisms.