Angiosperm DNA contamination by endophytic fungi: Detection and methods ofavoidance

PCR primers with broad applicability are useful in many molecular-based stu dies; however, their universality can compromise results when DNA contamina nts also are amplified. Eighty-one templates of Dahlia (Asteraceae), primar ily 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 materi al collected in Illinois, fungal DNA contaminated over 60% of the templates analyzed. Endophytic fungi often are symptomless symbionts living within t he above-ground tissues of their angiosperm hosts and are not affected by s urface sterilization techniques. Recent studies have revealed their widespr ead occurrence and broad host range. We also present field strategies for o btaining plant material to reduce the possibility of collecting infected le aves and a simple screening test for detecting fungal DNA in angiosperm tem plates.