Today is an exciting day in the Sessa lab, as two new projects supported by the National Science Foundation officially start today!

The first (NSF DBI 1802134) is a Thematic Collections Network grant whose goal is to digitize herbarium and fossil collections of ferns and lycophytes – this is a collaborative project involving a total of 39 institutions across the United States and is led by the University of California, Berkeley. UF is one of the core institutions and we will be managing subawards to several additional institutions to digitize several thousand collections belonging to these plant lineages.

The second (NSF IOS 1754911) is a research award for a project investigating the effects of ploidy level on fern gametophyte physiology and gene expression during periods of climate stress. This is a collaborative project between the Sessa lab, the Watkins lab at Colgate, and the Visger lab at University of California, Sacramento, and it is particularly fun that our research team is UF strong: both Eddie Watkins and Clayton Visger earned their PhDs at UF! Go Gators!


Abstract – Digitization TCN: Collaborative Research: The Pteridological Collections Consortium: An integrative approach to pteridophyte diversity over the last 420 million years
Ferns and their relatives (“pteridophytes”) arose approximately 420 million years ago and were the dominant plant groups for hundreds of millions of years afterwards. Today the pteridophytes are outnumbered by the diversity and abundance of other plant groups, such as those that bear flowers, but they remain diverse (with around 12,000 species), ecologically important, and are found throughout the world. This Thematic Collections Network (TCN) brings together 9 core institutions whose goal is to make digital images and data on the distribution and biology of 1.6 million fossil and modern ferns and their relatives available to researchers. This effort includes 39 US Museums and Herbaria that will provide on-line access of collections data to researchers worldwide who will be able to address pressing questions about the evolution, distribution, and biology of land plants. This project would train students and reach the public through teacher training opportunities, the development of curriculum and education boxes and through the production of informative science videos.

The Pteridological Collections Consortium TCN is an interdisciplinary initiative that will database, image, and disseminate information on an unprecedented number of extant and fossil pteridophyte specimens. The combining of neo- and paleobotanical collections data will produce an online resource via a Symbiota framework to enable research on the distribution, ecology, genetics, and deep-time evolution of an important group of vascular plants. Pteridophytes are important because they 1) are relatively diverse and have extensive global distributions, 2) are associated with evolutionary innovations that shaped adaptations to terrestrial ecosystems, 3) they are sensitive to local environmental conditions and play important roles in modern communities, and 4) they have an excellent fossil record for addressing deep-time questions. This award is made as part of the National Resource for Digitization of Biological Collections through the Advancing Digitization of Biological Collections program and all data resulting from this award will be available through the national resource (


Abstract – Collaborative Research: Understanding the effects of ploidal level on responses to global change in plants
Polyploidy, or whole genome duplication, occurs when an organism has one or more extra copies of all its chromosomes. This phenomenon is particularly common in plants, and recent estimates suggest that 15-30% of plants are polyploid. Polyploid species include a vast number of crop and other plants with economic and agricultural uses (e.g., cotton, wheat, potato, soybean). Polyploidy is known to influence a wide range of genetic and physiological features of plants, including physiological traits related to water use and photosynthesis. Polyploid plants can be more vigorous than diploids, have broader ecological niches, wider geographic distributions, and increased ability to invade new habitats, all driven by novel genetic combinations or gene expression patterns that can produce extensive changes in many traits. This project will investigate how polyploidy affects plants’ ability to respond to increases in temperature and decreases in available water (i.e., drought). Gene expression and physiological responses to drought and temperature will be measured for a set of fern species at different ploidal levels (amounts of polyploidy). Knowing whether and how ploidal level impacts these important components of the eastern forests of the United States will allow better prediction of how changes in temperature and water availability will influence community structure in natural ecosystems and will inform conservation efforts. Information on gene expression changes involved in tolerance of drought and increased temperatures has potential to assist crop breeding programs. An integral part of the project is to train postdoctoral associates, graduate students, and undergraduate students.

This project focuses on a set of fern species found in forests throughout the eastern United States. This is a naturally occurring plant system where polyploidy is prevalent, and whose members are ecologically important in the ecosystems where they occur. Gametophytes of six Dryopteris species, including two pairs of a polyploid and its parent taxa, will be grown in a multifactorial experiment with drought and temperature treatments. Data will be collected on reproductive and physiological ecology to determine how changes in temperature and water availability influence demographics and sporophyte recruitment from gametophytes as well as ability to recover from environmental stress. RNASeq will be used to generate gene expression profiles to evaluate differences between unstressed, dehydrated, and rehydrated gametophytes in different temperature treatments. Data will be analyzed using new methods for performing differential gene expression analyses on per-cell, per-biomass, and per-transcriptome bases. Results will be informative in quantifying the effects of experimental treatment on gene expression in organisms at different ploidy levels, including in crop plants and non-plant systems. The results of this work will improve the understanding of how ploidal level may influence species’ responses to environmental change. A workshop on how to effectively and engagingly teach plant life cycles will be held at the Botanical Society of America’s annual Botany conference, and will use a data-driven approach that incorporates results from the research.