People

The Wagner Lab: Enhancing plant development and adaptability to improve food security.

DiMaura Professor of Biology Doris Wagner is the inaugural director of the Penn Plant Adaptability and Resilience Center. Her research focuses on plant response to developmental and environmental cues. As immobile organisms, plants are masters at changing the fate of cells, tissues and organs and their ability to do so under diverse environmental conditions is important not only for plant survival and reproductive success but also for human sustenance and life on earth. Wagner conducted her undergraduate studies at the Technische Universität München in Germany, her PhD at the University of California in Berkeley and her Helen Hay Whitney foundation sponsored postdoc at Caltech. She was instrumental in establishing an international Plant Epigenomics Research Network, has served as elected member of the National Association for Arabidopsis research, has organized over 20 national and international symposia and conferences, is editor in chief or Current Opinions in Plant Biology and a fellow of the American Society of Plant Biologists.

At the University of Pennsylvania, her lab studies shoot architecture with emphasis on where and where flowers form. Altering shoot architecture has revolutionized agriculture. The Wagner lab is delineating the ‘wiring plan’ that controls this trait to enable its precise modulation for food security. A second question her lab studies is how plants withstand environmental stresses. Since the epigenome is the interface between the genome and the environment, the Wagner lab is developing methods for precision editing of the epigenome to enhance plant resilience and adaptability in changing climates.

The Gallagher Lab: How does the environment alter development? 

Dr. Gallagher is a Professor and Chair of the Department of Biology. She holds a PhD in Biology from the University of California, SanDiego where she worked on the development of stomata and cellular patterning in maize leaves. Dr. Gallagher began her work on root development as an NRSA supported post-doctoral fellow at Duke University. At Penn, Dr. Gallagher has continued her work on understanding root development with some breaks to serve as a Program Director and later as an Expert in Developmental Mechanism for the NSF. She has also served as an advisor for the European Research Council and reviewer for various international granting agencies.

For centuries researchers have asked how biological complexity develops; how does the organism unfold from a single fertilized cell. We now know in broad terms that genotype (G) plus environment (E) equals phenotype (P). One of the primary interests of the Gallagher lab is understanding how the environment (light, temperature, nutrient availability) affects phenotype. The lab asks this question in plants, because they are critical organisms in the food chain, but more importantly because much of cellular patterning in plants occurs post-embryonically. This allows the plant exquisite responsiveness to the environment and flexibility in developmental patterning. Understanding what processes the environment acts upon to alter development is a primary focus of the Gallagher lab. To answer these questions, the lab studies several different species of crop plants including rice, alfalfa and corn and the model system Arabidopsis thaliana, concentrating largely on root development. In these studies, the lab has found that environmental conditions affect the movement of proteins between cells and that differences in protein trafficking underlie species level differences in developmental patterning. Changes in root development that are of agricultural importance include tissue identities, surface to area ratios, metabolic load and nutrient uptake.

The Gregory Lab: Plant stress responses at the RNA level.

Brian D. Gregory is a Professor in the Department of Biology. His research focuses on the effects of three intrinsic features of RNA molecules, specifically their form (secondary structure), their various covalent chemical modifications (e.g. N6-methyladenosine (m6A)), and their interactions with RNA-binding proteins, on post-transcriptional transcriptome regulation. The lab has a specific focus on how these post-transcriptional regulatory processes affect the responses of plants to various abiotic and biotic stress conditions, with the goal of developing more stress and pathogen resilient crop species. Gregory conducted his undergraduate studies at the University of Arizona, his PhD at Harvard University, and his Damon Runyon Foundation sponsored postdoctoral work at the Salk Institute for Biological Studies. Gregory is an Editor for several research journals, including editor-in-chief of Academia Molecular Biology and Genomics. He was also recently elected a Fellow of the American Association for the Advancement of Science, and served as a panel member for the Congressional Briefing to “Understand the urgent need to advance RNA Science”.

The Gregory lab has found that chemical changes to the nucleotides within ribonucleic acid (RNA) molecules, so called RNA modifications, have a fundamental effect on post-transcriptional regulation both in the context of normal development and in plant stress response. In fact, changing the plant’s ability to add or remove these chemical modifications to messenger RNA (mRNA) nucleotides has drastic effects on the plant’s ability to properly respond to a wide range of both abiotic (e.g., cold, heat, and drought) and biotic (e.g., bacterial, and fungal pathogens). Thus, work in the Gregory lab is centered on determining the fundamental effects on plant stress response, with an eye towards using these chemical additions to RNA bases as a means for improving the ability of crop plant species to respond and adapt to abiotic and biotic stressors. Within the context of the UPenn Plant ARC, the work in the Gregory lab will be focused on using the provided tools to develop stress resistant crop plants to ensure global food security in the face of a globally changing environment.

The Helliker lab: Resilience in the natural world, clues from wild relatives.

Brent Helliker is a Professor in the Department of Biology. After obtaining an undergraduate degree from the University of Kansas and a Master’s degree from the University of Newcastle upon Tyne, Dr. Helliker obtained a PhD in Biology from the University of Utah where he worked on mechanisms that control stable isotope enrichment in grasses with different photosynthetic pathways. For postdoctoral work at the Carnegie Institute of Sciences Department of Global Ecology, Dr. Helliker shifted gears toward biometeorological approaches to measure photosynthesis and plant water loss over very large scales. From a consulting stint at the Isotope Hydrology Section of the International Atomic Energy Agency, Dr. Helliker joined the Biology Department at UPenn where he developed a research plan using stable isotopes to elucidate the physiology and ecology of a variety of plant types. More recently, Dr. Helliker has turned his attention back to the physiology and ecology of grasses and grasslands that dominate his birth state, Kansas.

Grass-dominated biomes began to emerge about 40 MY ago, and by about 20 MY ago were a fixture on every continent except Antarctica. Currently, grazing and fire are primary controls of grassland maintenance and distribution, but there are examples of grassland expansion seven million years before grazers appear in the fossil record, and examples of grassland expansion in the absence of fire.  To explain the appearance of grasslands without these primary controls, it is thought that an overall drier climate in the late Oligocene failed to support tree growth, and increased seasonality and variability of precipitation selected for grasslands.

To emerge from the forest understory and thrive in what was a new climate regime—and to develop into what was an entirely a new biome—grasses evolved novel physiologies and morphologies.  The Helliker lab has spent years examining the evolution of the photosynthetic pathway variation in grasses and has recently turned to water relations, examining how grasses maintain high photosynthetic productivity despite the often-unpredictable availability of water.

Our primary grain crops are domesticated grasses, and elucidating the physiological processes behind how wild grasses deal with water variability will inevitably reveal targets for crop improvement. Crop domestication occurred over thousands of years by selection for maximum yield under relatively predictable environmental conditions (e.g. irrigated fields), whereas wild grasses evolved global dominance as a response to variable environments. Crop domestication has, therefore, selected against the very adaptations that made grasses successful.  We hope to use both the structural and collaborative amenities that Plant ARC will bring to elucidate the mechanisms of how wild grasses deal with water variability, and where these mechanisms have been lost in domesticated grasses.

The Husbands Lab: Robustness and Resilience.

Aman Husbands is a Presidential Assistant Professor in the Department of Biology and a core member of the Penn Epigenetics Institute. His lab is interested in the mechanisms that govern complexity and reproducibility, two outcomes which seem in tension yet are both defining features of organismal development. Husbands acquired his Bachelor of Science (and his love of plant biology) from the University of Toronto in Canada. After immigrating to the US, he received his PhD from the University of California, Riverside then did his postdoc at Cold Spring Harbor Laboratory in Long Island, NY. He started his own lab at Ohio State in 2018 and was recruited to the University of Pennsylvania in 2022.

One of the central challenges posed by climate change is increased environmental variability. Plants are quite good at handling changes in environmental conditions, demonstrating remarkable resilience (or robustness). However, if environmental swings become too large, this natural resilience can be overwhelmed, with devastating effects on plant development and agricultural outputs. The Husbands lab is interested in determining the genetic mechanisms that give rise to the natural resilience of plants. Our long-term goal is to use this knowledge to increase the resilience of existing biological systems, stabilizing biology in the face of increased variability. Our strategy involves a wide range of complementary approaches. We work with species from both monocot (Brachypodium) and dicot (Arabidopsis) lineages. We pair genomic analyses and morphological measurements to link gene expression to changes in shape. We use evolution to guide us, leveraging existing pools of natural variation. We collaborate with mechanobiologists who think about how physical forces are used in nature to reliably construct complex organs. Finally, our thinking is guided by mathematical models which make predictions about resilience that we can directly test.

Claire Thurston-Emmert is a Philadelphia horticulturist who has spent her career cultivating the ecological health and beauty of public green spaces. After completing the Barnes Arboretum Horticulture Certificate Program and the Phipps Conservatory Sustainable Landcare Accreditation she jumped into the world of public gardens. She takes pride in creatively implementing sustainable practices, protecting and conserving urban wildlife, fostering spaces that encourage curiosity, and connecting anyone who will listen to the delights of the natural world. Claire is the Garden Supervisor at the James G. Kaskey Memorial Park at the University of Pennsylvania.