Scratching the surface: The in vitro research that will be critical for conserving exceptional plants to scale

Abstract

The conservation of threatened exceptional plants, which cannot be conserved by seed banking, requires in vitro technologies for many of the approaches needed for their long-term ex situ conservation. This study evaluated the current in vitro plant literature, as represented in Web of Science, to determine its taxonomic overlap with the families and genera of the 775 species currently listed as exceptional. Web of Science was searched using the terms micropropagation, somatic embryogenesis, zygotic embryo, and cryopreservation, and the target genera and families were identified in the more than 19,000 articles evaluated. There were five families with significant overlap between the in vitro literature and exceptional species: Fabaceae, Asteraceae, Orchidaceae, Arecaceae, and Rutaceae. However, there was less overlap at the level of genus, with Citrus, Coffea, and Quercus having the most articles. Significant gaps were also found, with 14 exceptional families and half of the exceptional genera having no representation in the Web of Science search results. The 20 exceptional species with the most articles were all economically important species, and these had 343 threatened congeners that could be prioritized for research. A highly important group of exceptional plants that was significantly under-represented in the literature was tropical woody species, which form the backbone of the diversity of the world’s threatened rainforests. Overall, there are areas of strength upon which to build future work, but significant gaps where research should be prioritized for effectively conserving exceptional plants.