I am a plant biochemist and molecular biologist interested in the elucidation of plant signaling and metabolic networks underlying plant interaction with the environment. I am particularly interested in applying interdisciplinary approaches, especially proteomics, metabolomics, mass spectrometry and bioinformatics to elucidating complex regulatory and metabolic networks in the cells and how they connect internal/external signals (including stresses) with plant physiological output/phenotypes. Only through a thorough understanding of how plant cell works, will it be possible to efficiently and effectively utilize the plant biofactory for the benefits of humanity and the environment.
Areas of Interest/Research
My research interests are focused on the signaling and metabolic networks underlying plant interaction with the environment. I have been particularly focused on two experimental systems. One is glucosinolate metabolism, and the other is guard cell signal transduction.
Glucosinolates are a group of naturally occurring thioglucosides, present in Brassica plants (e.g., canola and cabbage). Glucosinolate degradation products display diverse biological activities, including defense against pathogens and herbivores. From a human perspective, glucosinolate metabolites account for the distinctive flavors of cabbage and condiments, and anticarcinogenic properties of Brassica vegetables. Glucosinolate biosynthesis has been well studied. However, we know little about how the components in different pathways interact with glucosinolate biosynthesis to produce phenotypes and traits. Nor do we know how different layers of molecular control work together. The lack of such fundamental knowledge is a major reason why genetic engineering has been largely unsuccessful. Research in this project is focused on characterizing the regulatory and metabolic networks involving glucosinolate metabolism using multidisciplinary approaches. We aim to identify protein and metabolite changes in response to perturbation of glucosinolate metabolism (e.g., by genetic mutation), and to establish web database resources and integrate the data into glucosinolate networks. The process of networking will generate new testable hypotheses concerning glucosinolate metabolism and related pathways. It will reveal novel components of the molecular networks and establish a community resource of plant molecular networks. Understanding of the molecular networks is essential for modeling and targeted engineering of useful plant metabolites. The ultimate goal is to use the immense biosynthetic potential of plants as an efficient, environmentally friendly and renewable source of fine chemicals and pharmaceuticals. I have received a 5-year CAREER award, published more than 15 research articles, had many oral and poster presentations, as well as trained many students at different levels.
Guard cells are highly specialized plant epidermal cells that enclose tiny pores called stomata. Stomatal movements control uptake of carbon dioxide and loss of water, and thus play important roles in plant growth and acclimation to environmental stresses. The plant hormone abscisic acid (ABA) is a key indicator of drought stress. ABA induces stomatal closure via an intricate intracellular signaling network in guard cells, thereby promoting plant water conservation. It is our central hypothesis that protein redox modification and dynamic changes in key metabolites are critical regulatory mechanisms in ABA signaling. We are testing the hypothesis by pursuing: identification of guard cell proteins whose redox status is altered in response to ABA and determination of their specific redox-sensitive amino acid residues, quantification of ABA-induced changes in metabolites, and integration of the new information into a dynamic model of ABA-induced stomatal closure. Using advanced proteomics tools, we have identified over 1500 stomatal proteins and characterized redox regulation of many novel proteins. In addition, we have established targeted and untargeted metabolomics methods for analyzing hundreds of key stomatal metabolites. These accomplishments are significant because they revealed novel components of ABA signaling networks and provided knowledge of regulatory mechanisms underlying stomatal movements that will help to develop crops with enhanced stress tolerance and productivity. I have received three NSF grants on this project, published more than 20 research articles, had many oral and poster presentations, as well as trained many students at different levels.
In addition to hypothesis generation projects, another major component of my research program has been hypothesis testing, i.e., characterizing molecular and physiological functions of specific genes and proteins identified by the “omics” work. One of the projects was focused on understanding two key steps in the methionine chain-elongation pathway. The functions of seven new genes have been characterized. The results have been published in the Plant Journal, Journal of Biological Chemistry, and New Phytologist, which are top international journals in plant biology areas. In addition, we have identified new kinases in guard cell signaling. We have characterized redox regulation of two important kinases, and the results have been published in the Plant Journal and recently in BBA – Proteins and Proteomics. The findings have not only filled in fundamental knowledge gaps in plant signaling, but also created important stepping stones towards potential biotechnological applications in crop improvement.
Office Hours: by appointment
Office: 438 Cancer and Genetics Research Complex
Phone: (352) 273-8330
Fax: (352) 273-8104
2033 Mowry Rd, CGRC Bldg, Rm 438
University of Florida
P.O. Box 103610
Gainesville, FL 32610