Reliable DNA ploidy determination in dehydrated tissues of vascular plants by DAPI flow cytometry—new prospects for plant research

Abstract

Only fresh plant material is generally used for rapid DNA ploidy estimation by flow cytometry (FCM). This requirement, however, substantially limits convenient FCM application in plant biosystematics, population biology, and ecology. As desiccation is a routine way for sample preservation in field botany, potential utilization of dehydrated tissues of vascular plants in FCM research was examined. Standard DAPI protocol was employed to evaluate the performance of 60 air-dried species, spanning more than 100-fold range of nuclear DNA amounts. Multiploid Vaccinium subg. Oxycoccus was selected as model taxon for detailed investigation and cytotype comparison. A majority of analyzed plants yielded distinct peaks with reasonable coefficients of variation after several months of storage at room temperature. Fluorescence intensity of nuclei isolated from desiccated tissues was highly comparable with that for fresh material, allowing reliable DNA ploidy estimation. Deep-freezer preservation substantially extended Vaccinium samples lifetime (at least to 3 years) and maintained high histogram resolution. The introduced approach eliminates the need for fresh material in many vascular plants and thus opens new prospects for plant FCM. Convenient cytotype investigation in field research and retrospective ploidy determination in already herbarized samples are among the principal advantages.