Department of Plant and Microbial Biology
Education and Workforce Development Platform Director, Associate Professor
3112A Plant Sciences Building
Anemia induced by iron deficiency is one of the most prevalent nutritional disorders in the world. Most people obtain nutritional iron predominantly from plants. Our research focuses on understanding the molecular mechanisms that plants use to uptake, transport, and utilize iron, and respond to low iron conditions.
We use genomics, molecular biology and genetics to identify root-specific transcriptional responses that regulate physiological alterations associated with iron deprivation in the model plant, Arabidopsis thaliana. Our work resulted in the first whole-genome, high-resolution transcriptional profile of iron deficiency in the root, and led to the identification of two regulatory genes that play a key role in how plants respond to low iron conditions.
Our continued efforts are focused on identifying additional iron deficiency response regulators and their corresponding gene targets, with the long-term goal of elucidating gene regulatory networks involved in plant iron homeostasis. Ultimately, this information may lead to the generation of crops with increased nutritional content and increased yield when grown in poor soils.
- Plant Physiology (PB 421)
Ph.D. Molecular Genetics University of Georgia 2005
B.S. Biology University of North Carolina, Chapel Hill 1998
Area(s) of Expertise
Molecular Biology of Plant Nutritional Homeostasis
- BTS Is a Negative Regulator for the Cellular Energy Level and the Expression of Energy Metabolism-Related Genes Encoded by Two Organellar Genomes in Leaf Tissues , MOLECULES AND CELLS (2022)
- POPEYE intercellular localization mediates cell-specific iron deficiency responses , PLANT PHYSIOLOGY (2022)
- A hybrid model connecting regulatory interactions with stem cell divisions in the root , Quantitative Plant Biology (2021)
- Broadening the impact of plant science through innovative, integrative, and inclusive outreach , PLANT DIRECT (2021)
- Solving the puzzle of Fe homeostasis by integrating molecular, mathematical, and societal models , CURRENT OPINION IN PLANT BIOLOGY (2021)
- BioVision Tracker: A semi-automated image analysis software for spatiotemporal gene expression tracking in Arabidopsis thaliana , Methods in Cell Biology (2020)
- Computational solutions for modeling and controlling plant response to abiotic stresses: a review with focus on iron deficiency , Current Opinion in Plant Biology (2020)
- Iron homeostasis and plant immune responses: Recent insights and translational implications , Journal of Biological Chemistry (2020)
- MAGIC: Live imaging of cellular division in plant seedlings using lightsheet microscopy , Methods in Cell Biology (2020)
- Automated Imaging, Tracking, and Analytics Pipeline for Differentiating Environmental Effects on Root Meristematic Cell Division , Frontiers in Plant Science (2019)
"Project is in support of PSI" Plant disease resistance proteins of the nucleotide binding leucine-rich repeat (NLR) type are activated and induce a strong defense response known as effector-triggered immunity or ETI, upon recognition of specific pathogen-derived effector proteins. The effectiveness of this system depends on its inactivity when the cognate pathogen is not present, rapid induction when a pathogen is recognized followed by a rapid suppression after induction. The ubiquitin-proteasome pathway, mediated by the sequential actions of E1 (ubiquitin-activating), E2 (ubiquitin-conjugating) and E3 (ubiquitin ligase) enzymes is a major protein modification process found in all eukaryotes. Our preliminary data indicates that maize ZmCER9 E3-ligase mediates degradation of the Rp1-D disease resistance protein specifically after its activation. We have further evidence that CER9 may act in a similar way to degrade other plant resistance proteins once activated. This appears to be a previously undescribed mechanism that mediates the deactivation of the defense response after activation. Based on its homology, ZmCER9 appears to be a component of the endoplasmic reticulum associated degradation (ERAD), a fundamental eukaryotic quality-control system that degrades incorrectly folded proteins. In plants this pathway has been relatively poorly characterized and there are no known substrates of the branch of the pathway mediated by CER9. Activated Rp1-D may represent the first known substrate of this branch of the ERAD pathway in plants. We hypothesize that ERAD-Mediated Degradation of Activated NLRs (EMDAN) is a general mechanism for the deactivation of ETI in plants. We propose to use a range of molecular, genomics and cell biology techniques to characterize the role of CER9, ERAD and related pathways involved in ubiquitin/proteasome associated processes in controlling ETI in maize and Arabidopsis.
Iron (Fe) is an essential co-factor in ubiquitous metabolic processes, but it is also potentially toxic to cells. To meet organismal needs while avoiding toxicity, the physiological availability of Fe must be closely regulated. This is achieved by proteins that sense iron status and regulate a cascade of signaling activity to balance iron uptake from diet, storage in tissues, and transport from organ to organ. Errors in the choreography of this Fe-handling system lead to diseases of iron deficiency (e.g. anemia) or Fe excess (e.g. hemochromatosis). In studies of Fe homeostasis, physiological indicators of organism health are routinely observed, but the levels of Fe transporter proteins and details of their regulatory interactions are not readily quantified in situ. Reductionist approaches identify the function of individual proteins and their immediate signaling partners, but these approaches do not explain the complex, interdependent, and multiscale phenomenon of systemic homeostasis. By coupling computational systems modeling with in vivo experiments, however, existing knowledge about Fe handling at the cellular, organ, and organism levels can be integrated. This makes it possible to assess the validity of potential biological mechanisms and identify profitable experimental strategies that efficiently pin down causal molecular phenomena. Furthermore, mathematical models can be used to learn from model systems and then generalize to analogous functional relationships across organisms. This is fortuitous as the model plant Arabidopsis thaliana exhibits modes of Fe regulation that are analogous to those in humans, and Arabidopsis offers a particularly versatile tool for studying cell-type and organ-specific features of iron signaling. Ubiquitin ligases are a particularly important class of Fe-sensor proteins conserved between plants and animals. These intracellular actors bind Fe at specific domains. Fe binding alters their stability and modulates their ability to post-translationally regulate Fe deficiency response proteins. We previously identified BRUTUS (BTS) to be the iron-binding ubiquitin ligase in Arabidopsis and demonstrated that its absence leads to systemic Fe excess. The goal of this project is to use mathematical models and the model organism Arabidopsis to delineate the molecular rules that allow BTS, an enzyme confined to the plant vasculature, to mediate systemic Fe homeostasis. Based on our preliminary mathematical model, we propose the novel hypothesis that BTS plays opposing roles in the plant root and shoot, participating in tissue-specific signaling pathways that enable sensing of Fe status at the principal site of Fe usage (shoot) and communicate Fe need to the site of Fe uptake (root). Our specific Aims are: Aim 1 - Determine how Fe binding modulates the stability, localization and regulatory activity of BTS. Aim 2 - Characterize how oligomerization regulates the mobility, stability, and regulatory activity of ILR3, and, consequently, Fe deficiency response in the root. Aim 3 - Identify the molecular mechanism of BTS function in the shoot and its impact on shoot-to-root signaling.
The College of Agriculture and Life Sciences (CALS) at NCState trains students to address challenges in agricultural productivity, the safety and nutrition of the food supply, and the application of plant and animal products to disparate uses such as biofuels. This grant will provide tuition for a total of about 15 Masters students in Biochemistry over 5 years. Graduates of the program will be prepared to find good-paying jobs in the agricultural and food industry in North Carolina, or to continue their academic training. Currently16% of the jobs in NC are based in agriculture (NC Department of Agriculture), with over 80 agbiotech companies in the state. Training in a basic science such as biochemistry will provide students the flexibility to adapt to changes in the job market. The goal of this proposal is two-fold: 1) to diversify the workforce by providing educational opportunities for academically-talented low-income and minority students, and 2) to promote interdisciplinary research and training in biochemistry applied to problems in agriculture and human health. The grant is focused on research areas in nutrition and metabolic regulation that link biochemistry to applications in the Departments of Food, Bioprocessing and Nutrition Sciences; Plant and Microbial Biology; and Animal Science. Students will be recruited from throughout NC. The Masters program is less diverse than the undergraduate program at NCState, justifying the need to promote minority recruitment. The grant will provide tuition for in-coming students to complete a thesis Masters degree. Students will be responsible for paying living expenses. A curriculum and research experience will be devised for each student according to their background and personal goals. During their first year, new students will develop a strong background in biochemistry by completing the 3 core biochemistry classes. The remaining 5 courses will be based on the student's interests. A Fall seminar series will introduce students to research opportunities with the 25 faculty members from the 4 departments in CALS as well as industry opportunities in the RTP area. This seminar will promote interdisciplinary interactions between diverse labs, all requiring knowledge of metabolic pathways to address contemporary problems in microbes, plants, animals and human nutrition. During the Spring semester, students will select 2 labs to investigate further for a month each before choosing a lab for their Masters research. We anticipate the average time to degree will be 2.5 years. During the second year students will participate in professional development discussions to prepare for post-graduation. Overall this grant will provide training for low-income and minority students to contribute to solving challenges in agriculture and human health including environmental changes due to global warming, increased population pressures, and the relationship between nutrition and health.
Minimizing crop loss and increasing output, across the food supply chain, will increase the economic viability of US growers and the global economic competitiveness of industry and stakeholder partners. We have assembled a diverse team across different National and International Universities with faculty that have track records of convergent research, education, and outreach. We will be well positioned to implement a Networks of Networks with diverse backgrounds, ethnicities, genders, experiences, and disciplines to drive research and innovation. Students and postdocs will be exposed to hands-on learning, on-farm technology training, cooperative extension, commercialization, industry engagement, and transdisciplinary education to create a highly trained workforce that is equipped to address food security and safety challenges.
We propose an Engineering Research Center for Green and Climate Resilient Built Environments (Green CriBs), which will drive innovation, engineering and widespread adoption of novel transparent envelope window and building materials to provide extreme thermal insulation together with dynamic and responsive light admittance for the built environment, its occupants and activities. Doing so will maximize the climate resilience of society, enhance environmental justice, reduce greenhouse gas emissions and accelerate grid decarbonization.