Functional and ecological diversification of underground organs in Solanum

Edeline Gagnon; Ludwig Baldaszti; Peter Moonlight; Sandra Knapp; Caroline E R Lehmann; Tiina Särkinen

doi:10.3389/fgene.2023.1231413

Functional and ecological diversification of underground organs in Solanum

Front Genet. 2023 Oct 10:14:1231413. doi: 10.3389/fgene.2023.1231413. eCollection 2023.

Authors

Edeline Gagnon^{1

2

3}, Ludwig Baldaszti^{2

4}, Peter Moonlight⁵, Sandra Knapp⁶, Caroline E R Lehmann^{2

4}, Tiina Särkinen²

Affiliations

¹ Department of Integrative Biology, University of Guelph, Guelph, ON, Canada.
² Tropical Diversity Section, Royal Botanic Garden Edinburgh, Edinburgh, United Kingdom.
³ Chair of Phytopathology, TUM School of Life Sciences, Technical University of Munich, Freising, Germany.
⁴ School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom.
⁵ Botany, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland.
⁶ Natural History Museum, London, United Kingdom.

Abstract

The evolution of geophytes in response to different environmental stressors is poorly understood largely due to the great morphological variation in underground plant organs, which includes species with rhizomatous structures or underground storage organs (USOs). Here we compare the evolution and ecological niche patterns of different geophytic organs in Solanum L., classified based on a functional definition and using a clade-based approach with an expert-verified specimen occurrence dataset. Results from PERMANOVA and Phylogenetic ANOVAs indicate that geophytic species occupy drier areas, with rhizomatous species found in the hottest areas whereas species with USOs are restricted to cooler areas in the montane tropics. In addition, rhizomatous species appear to be adapted to fire-driven disturbance, in contrast to species with USOs that appear to be adapted to prolonged climatic disturbance such as unfavorable growing conditions due to drought and cold. We also show that the evolution of rhizome-like structures leads to changes in the relationship between range size and niche breadth. Ancestral state reconstruction shows that in Solanum rhizomatous species are evolutionarily more labile compared to species with USOs. Our results suggest that underground organs enable plants to shift their niches towards distinct extreme environmental conditions and have different evolutionary constraints.

Keywords: geophytes; niche breadth; niche shifts; range size; rhizomes; root sprouters; tubers.

Grants and funding

This work was supported by a postdoctoral fellowship to EG, from the “Fonds de recherche du Québec en Nature et Technologies” (FQRNT). Herbarium and field visits for collection of occurrence data were in part funded by the US National Science Foundation Planetary Biodiversity Inventory Program (“PBI Solanum: a worldwide treatment”, DEB-0316614).