Effect of fuchsin fixation of pollen on DNA barcode recovery

Pollen grains attached to insects are a valuable source of ecological information which can be used to reconstruct visitation networks. Morphological pollen identification relies on light microscopy with pollen usually stained and mounted in fuchsin jelly, which is also used to remove pollen from the bodies of insects. Pollen embedded in fuchsin jelly could potentially be used for DNA barcoding and metabarcoding (large-scale taxonomic identification of complex mixed samples) and thus provide additional information for pollination networks. In this study, we determine whether fuchsin-embedded pollen can be used for downstream molecular applications. We evaluate the quality of plant barcode (ITS) sequences amplified from DNA extracted from both fresh (untreated) pollen, and pollen which had been embedded in fuchsin jelly. We show that the addition of fuchsin to DNA extraction does not impact DNA barcode sequence quality during short-term storage. DNA extractions from both untreated and fuchsin-treated pollen produced reliable barcode sequences of high quality. Our findings suggest that pollen which has been collected, stained, and embedded in fuchsin jelly for preliminary microscopy work can be used within several days for downstream genetic analysis, though the quality of DNA from pollen stored in fuchsin jelly for extended periods is yet to be established.