Postdoctoral Fellowship: PRFB: The power of plasticity: aquatic plants' response to an ever-changing environment

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2024, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment, and Phenotypes. The fellowship supports research and training of the fellow that will contribute to the area of Rules of Life in innovative ways. Few structures are as ubiquitous or essential to life on earth as the leaf.

These photosynthetic factories use energy from sunlight to convert water and carbon dioxide into sugar, which in turn supports a multitude of life forms from insects to humans. Leaves, with their tremendous array of shapes and sizes, demonstrate the remarkable adaptability of plants. Due to their relative immobility, some plants have evolved the ability to produce multiple types of leaves on a single plant as a response to changes in their surroundings.

This trait, known as heterophylly, is exemplified by aquatic plants which often produce different types of leaves above and below the water. In some cases, plants even modify how they take up carbon dioxide depending on their environment. A convenient example of both is found in Littorella uniflora, a freshwater plant that alters its leaf shape and photosynthetic pathway in response to changing water levels.

While it’s simple to observe these physical changes, the mechanisms behind them remain largely unexplored. This research seeks to bridge the gap between genetics and the environment by addressing how plants adapt and respond to highly variable ecosystems. Broader impacts from this work focus on training and mentoring graduate and undergraduate students, engaging the public through digital media and academic outreach programs, and making findings accessible through lectures and publications.

Furthermore, the results of this project will be essential to guiding conservation and agricultural practices in the face of a shifting and uncertain global climate.

Facultative shifts in leaf anatomy and physiology provide alternate but overlapping methods that allow aquatic plants to maximize photosynthetic efficiency in response to changes in their immediate surroundings. The project aims to use L. uniflora as a model to elucidate the molecular underpinnings of heterophylly and facultative CAM photosynthesis using high-resolution transcriptomic methods and comparative phylogenetics.

Close comparison of leaf development under a range of conditions will allow characterization of the relationship between leaf form and function. Alongside anatomical observations, single-cell and bulk RNAseq will be used to generate an atlas of gene expression in developing leaves, and facilitate identification of key developmental genes and pathways driving shifts in anatomy and physiology.

The association of gene expression and development will be further confirmed using in-situ hybridization. Finally, transcriptomic data will be compared with other plants, in particular within Plantaginaceae, to characterize changes in evolutionary rates, signatures of selection, and expansion/contraction of gene families related to adaptations to the aquatic environment.

Comparative transcriptomic analyses will contribute to a broader perspective of genetic adaptation across land plants, placing the results in an evolutionary context. This project will provide students with training in wet lab techniques and bioinformatic analysis as well as education in aquatic botany and plant developmental and evolutionary biology.

Mentees will also be integrated into public outreach focused on aquatic plants and their unique adaptations to freshwater environments. To ensure accessibility, all transcriptomic data generated by this research will be made publicly available through NCBI and the Sequence Read Archive (SRA) with anatomical observations and images deposited on Dryad and a public GitHub repository.

Likewise, any bioinformatics scripts and pipelines used in analyses will be thoroughly documented on GitHub.

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.