Biochemistry - CAFNR
Research at a glance
Area(s) of Expertise
Study of plant hormone jasmonate-mediated defense signaling and plant lipid metabolism.
JA SIGNALING IN WOUND RESPONSE AND INSECT RESISTANCE
Our research involves the study of small signaling molecules that cells use to detect extracellular stimuli and to coordinate intra- and intercellular responses. To compensate for their lack of mobility, plants rely heavily on chemical cues to interact with their surroundings. This is one reason why plants are rich sources of pharmaceuticals and provide attractive models for studying chemically mediated cell signaling. We employ highly sensitive mass spectrometry-based methodologies to capture and monitor plants’ chemical signals. The combined approach of mass spectrometry and genomics in the model plant Arabidopsis thaliana has allowed us to identify novel players in defense signaling pathways.
Recently, our focus has been on describing mechanisms that control optimal levels of the plant hormone jasmonate (JA). JAs are a group of oxylipins produced by the oxidative metabolism of polyunsaturated fatty acids, analogous to eicosanoids in animals. Similar to eicosanoids, JAs play important roles in wound healing and immune responses. While the core JA biosynthetic pathway has been elucidated, how JA biosynthesis is initiated, maintained, or terminated remains unclear. One of the major goals of our current research is to gain a better understanding of the initiation and termination of JA signals and to investigate their roles in plant responses to wounding. This project has the potential to identify previously unrecognized regulatory mechanisms of JA signaling and JA-dependent wound responses. It is also expected to provide new insights into how plants prioritize growth versus defense by studying mutants that appear to defy the growth-defense tradeoff rule.
When a part of a plant is attacked by insects, the plant activates defense responses not only in the damaged area but also throughout the plant. This indicates the existence of a long-distance signaling system. We and others have discovered that this response is very rapid, traveling at a rate of several centimeters per minute, and triggers de novo synthesis of JA in undamaged regions of the plant. The wound signal is upstream of JA biosynthesis and involves ligand-gated ion channels called glutamate receptor-like (GLR) proteins. Related proteins mediate fast excitatory neurotransmission in animals. Parallels between mammalian neurotransmission and plant systemic wound responses include rapid propagation of cytosolic calcium (Ca2+) concentration changes. We are currently investigating how GLRs, glutamate, Ca2+, and JA coordinate system-wide defense responses.
The knowledge obtained from our JA research may significantly benefit agriculture. Chemical pesticides and fungicides have long been the prevailing strategy to manage insects and fungal pathogens, but there is growing public recognition of the environmental and human health concerns posed by synthetic pesticides. The study of plant’s built-in defense mechanisms controlled by JA is an important step toward the development of environmentally friendly, effective, and sustainable pest control. JA is also a potent inducer of numerous specialized metabolites that serve as a renewable source of high-value natural products for human use, such as nutraceuticals. The study of JA-mediated wound responses and systemic signaling will help us understand how the fundamental process of cell-damage sensing and system-wide communication has independently evolved in plants and animals, despite their drastically contrasting lifestyles, using conserved biochemical principles.
PLANT OIL METABOLIC ENGINEERING
The second main focus of research in the Koo lab is plant oil metabolic engineering. Vegetable oils are the most energy-dense natural carbon compounds used for food, fuels, and chemical feedstocks, and there is a growing demand to meet the needs of the exponentially growing world population. We are currently developing transgenic plants with increased oil content in seeds as well as vegetative tissues. Specifically, we have generated Camelina sativa germplasms with increased seed oil contents. Camelina is an emerging oilseed crop for both food and fuel, characterized by several desirable agronomic traits. Notably, Camelina is easily transformable using the Agrobacterium floral vacuum infiltration method and shares many of the genes (> 90%) involved in lipid metabolism with Arabidopsis, making it amenable to transferring the vast knowledge accumulated in Arabidopsis.
In our research, we have discovered a novel approach to increase triacylglycerol (TAG) content in leaves. While leaves typically do not accumulate significant amounts of TAG, producing it in vegetative tissues such as leaves has several advantages. One key benefit is that natural storage organs, like seeds, represent only a small fraction of a plant’s biomass. The transgenic lines we have developed with higher oil contents are also used to study the molecular and biochemical basis for trade-offs with respect to other storage compounds (e.g., protein), plant biomass, or seed set. These trade-offs have historically posed challenges in engineering efforts. To address these complexities, we employ a diverse and integrated strategy, including transcriptomic, proteomic, and metabolic profiling, as well as flux network analyses, through collaboration across several labs.
The Koo lab is committed to improving STEM education by providing multidisciplinary training to college students, graduates, and postgraduates. As part of an ongoing National Science Foundation-sponsored project, science literacy programs called Sci-LiFT (Science Literacy for Future Teachers) and its sister program Sci-FEST (Science Literacy for Future Educators in Science and Technology) were developed for high school teachers and students who are in training to become secondary school science teachers. Participants engage in real laboratory research on topics relevant to projects in the lab and develop high school teaching modules. For more information, visit our websites at https://munsfscilift.wordpress.com and https://muscifest.com/.
- Ph.D., Michigan Sate University
- BIOCHM 4270/7270: Biochemistry (Spring & Fall), comprehensive biochemistry course
- BIOCHM 8060: Ethical Conduct of Research