Micro-CT scanning has become an established tool in investigating plant structure and function. Its non-destructive nature, combined with the possibility of three-dimensional visualization and virtual sectioning, has allowed novel and increasingly detailed analysis of complex plant organs. Interactions among plants, including between parasitic plants and their hosts, can also be explored. However, sample preparation before scanning becomes crucial due to the interaction between these plants, which often differ in tissue organization and composition. Furthermore, the broad diversity of parasitic flowering plants, ranging from highly reduced vegetative bodies to trees, herbs, and shrubs, must be considered during the sampling, treatment, and preparation of parasite-host material. Here two different approaches are described for introducing contrast solutions into the parasite and/or host plants, focusing on analyzing the haustorium. This organ promotes connection and communication between the two plants. Following a simple approach, details of haustorium tissue organization can be explored three-dimensionally, as shown here for euphytoid, vine, and mistletoe parasitic species. Selecting specific contrasting agents and application approaches also allow detailed observation of endoparasite spread within the host body and detection of direct vessel-to-vessel connection between parasite and host, as shown here for an obligate root parasite. Thus, the protocol discussed here can be applied to the broad diversity of parasitic flowering plants to advance the understanding of their development, structure, and functioning.
Bibliographical noteFunding Information:
I would like to thank Dr. Simone Gomes Ferreira (Microtomography Laboratory, University of Sao Paulo, Brazil) and Dr. Greg Lin (Center for Nanoscale Systems, Harvard University, USA) for their paramount help and indispensable user training for different microtomography systems and data analysis software. I also thank the staff at the EEB Greenhouse at the University of Connecticut (USA), especially Clinton Morse and Matthew Opel for providing the specimens of Viscum minimum. Dr. John Wenzel provided the opportunity and great help for the sampling of Pyrularia pubera. MSc. Carolina Bastos, MSc. Yasmin Hirao, and Talitha Motta greatly helped with the sampling of Scybalium fungiforme. MSc. Ariadne Furtado, and Drs. Fernanda Oliveira and Maria Aline Neves provided the reference for the use of phloxine B for the analysis of endophytic fungi. Funding was provided by the Coordination for the Improvement of Higher Education Personnel (CAPES, Brazil) and the Harvard University Herbaria (USA).
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