Species survey of leaf hyponasty responses to warming plus elevated CO2

Authors: THOMAS, MICHAEL - University Of Toledo; ROBERTS, REGAN - University Of Toledo; HECKATHORN, SCOTT - University Of Toledo; Boldt, Jennifer

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2024
Publication Date: 1/11/2024
Citation: Thomas, M., Roberts, R., Heckathorn, S.A., Boldt, J.K. 2024. Species survey of leaf hyponasty responses to warming plus elevated CO2. Plants. 13(2). Article 204. https://doi.org/10.3390/plants13020204.
DOI: https://doi.org/10.3390/plants13020204

Interpretive Summary: Higher temperatures and elevated carbon dioxide concentrations can cause an upward bending of leaves in some plants. This response leads to less crop growth and lower yields. However, it is not known how common this response is across plant species. This study identified that this upward bending of plant leaves in response to higher temperatures and elevated carbon dioxide occurs across multiple plant families. It is more prevalent and pronounced in plants that have a compound leaf structure (like tomato) and less so in plants with simple leaves (like pepper). This knowledge identifies that a lack of upward leaf bending in response to high temperatures and elevated carbon dioxide is a key trait that breeders should select in the development of new, more climate-resilient, cultivars.

Technical Abstract: Atmospheric carbon dioxide (CO2) concentrations are increasing and may exceed 800 ppm by 2100. This is increasing global mean temperatures and the frequency and severity of heatwaves. Recently, we showed for the first time that the combination of chronic warming and elevated carbon dioxide (eCO2) caused extreme upward bending (i.e., hyponasty) of leaflets and leaf stems (petioles) in tomato (Solanum lycopersicum), which reduced restricted growth. Here, we examined additional species to test the hypotheses that warming + eCO2-induced hyponasty is restricted to compound-leaved species, and/or limited to the Solanaceae. A 2x2 factorial experiment with two temperatures, near-optimal and supra-optimal, and two CO2 concentrations, ambient and elevated (400, 800 ppm), was imposed on similarly-aged plants for 7 – 10 days, after which final petiole angles were measured. Within Solanaceae, compound-leaf, but not simple-leaf, species displayed increased hyponasty with the combination of warming + eCO2 relative to warming or eCO2 alone. In non-Solanaceous species, hyponasty, leaf-cupping, and changes in leaf pigmentation as a result of warming + eCO2 were variable across species.