Angiosperm DNA contamination by endophytic fungi: detection and methods of avoidance

PCR primers with broad applicability are useful in many molecular-based studies; however, their universality can compromise results when DNA contaminants also are amplified. Eighty-one templates ofDahlia (Asteraceae), primarily extracted from native Mexican populations, were tested for the presence of fungal contaminants; out of these, almost 1 in 7 templates (13.6%) was contaminated. In a second survey across 12 angiosperm families using material collected in Illinois, fungal DNA contaminated over 60% of the templates analyzed. Endophytic fungi often are symptomless symbionts living within the above-ground tissues of their angiosperm hosts and are not affected by surface sterilization techniques. Recent studies have revealed their widespread occurrence and broad host range. We also present field strategies for obtaining plant material to reduce the possibility of collecting infected leaves and a simple screening test for detecting fungal DNA in angiosperm templates.