Using seed-free plants to link diversity in stomatal function with ecological strategy

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Plants obtain carbon dioxide from the atmosphere through microscopic pores on the leaves called stomata. When stomata open to obtain carbon dioxide, water is lost to the atmosphere by evaporation. Due to the tradeoff between carbon gain used for plant growth and water loss that might lead to dehydration, there are many signals from the environment and plant that trigger stomatal opening and closing. This award aims to investigate whether there is variation across fern species in the responses of stomata to environmental conditions, and whether this variation can be linked to ecological strategies and habitat preference. This project will focus on ferns and lycophytes, ancient groups of plants that have comparatively simple stomatal behavior, in which variation in stomatal function is likely to have a large impact on plant growth and survival. The results will increase understanding of how stomatal responses to the environment evolved and how they could be manipulated in agricultural species to improve plant water use and productivity. This project will also inform the public and students on the dynamic nature of plants, to help raise awareness of how responsive and alive these otherwise static features of the landscape are, as well as provide research training to undergraduate students. This project will investigate three key hypotheses using comparative studies to characterize the natural diversity of stomatal function found in seed-free plants. The first hypothesis proposes that eliminating the threat of water limitation on survival through the evolution of an aquatic growth habit or vegetative desiccation-tolerance, drives the evolution of novel stomatal function, particularly in the regulation of stomatal closure. The second proposes that the evolution of unique leaf hydraulic properties facilitates the evolution of novel stomatal regulation. Finally, this project will test whether there is coordinated evolution in stomatal regulation, leaf hydraulic traits and ecological strategy across an ecological diverse fern family. This project will draw upon a large living collection of diverse fern and lycophyte species and field experiments to address these hypotheses, primarily through comparative studies of stomatal and plant hydraulic physiology between closely related yet ecologically dissimilar species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.