Education

Research Area

Study of small signaling molecule-mediated defense responses against biotic stress and lipid metabolism in plant.

Research Description

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‒one reason why plants are so rich in pharmaceuticals and provide attractive models for studying chemically mediated cell signaling. We use highly sensitive mass spectrometry-based methodologies to capture and to monitor plants’ chemical signals. The combined approach between 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 to describe mechanisms that control optimal levels of 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. Although the core JA biosynthetic pathway has been elucidated, how JA biosynthesis is initiated, maintained or terminated is unclear. One of the major goals of current research is to gain a better understanding of the termination of JA signals and to investigate its roles in plant response to wounding. This project has potential to identify previously unrecognized regulatory mechanisms of JA signaling and JA-dependent wound response. This project is also expected to provide new information about how plants prioritize growth versus defense by studying the mutants that appear to defy the growth-defense-tradeoff rule.

When a part of plant is attacked by insects the plant activates defense responses in not only the area where it is directly damaged but also throughout the plant indicating the existence of 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 the system undamaged regions. 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 the mammalian neurotransmission and plant systemic wound response include rapid propagation of cytosolic calcium (Ca²⁺) concentration changes. Investigation is underway to study how GLRs, glutamate, Ca²⁺, and JA coordinate system-wide defense response.

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 today, there is wide public recognition of environmental and human-health concerns imposed by using synthetic pesticides. The study of plant’s built-in defense mechanisms controlled by JA is an important step toward development of environmentally friendly, effective and sustainable pest control. JA is also a potent inducer of numerous specialized metabolites that are a renewable source of high-value natural products for human use such as nutraceuticals. JA mediated wound response and systemic wounding signaling study will help us understand how the fundamental process of cell-damage sensing and system-wide communication has independently evolved in plants and animals with such a drastically contrasting lifestyles yet using conserved biochemical principles.

Plant oil metabolic engineering

The second main thrust of research in the Koo lab involves plant oil metabolic engineering. Vegetable oils are the most energy dense natural carbon compounds used for food, fuels, and chemical feedstocks, and there has been a rising demand to keep up with the needs of the exponentially growing world population. We are currently developing Camelina sativa germplasms with increased seed oil contents. Camelina is an emerging oilseed crop for both food and fuel with a number of desirable agronomic traits. Camelina is easily transformable using agrobacterium floral vacuum infiltration method, and shares many of the genes (> 90%) involved in lipid metabolism with arabidopsis which makes it amenable to transfer the vast knowledge accumulated in arabidopsis. The developed transgenic lines 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 that have hampered past engineering efforts. A diverse and integrated strategy, including transcriptomic, proteomic, and metabolic profiling, and flux network analyses are employed in a collaboration across several labs.

STEM education

The Koo lab seeks to improve STEM education by providing multidisciplinary training to college students, graduates and postgraduates. As part of ongoing National Science Foundation sponsored project, science literary 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 a high school teaching module. For more information, visit our websites at https://munsfscilift.wordpress.com and https://muscifest.com/.

Selected Publications

Mulaudzi T, Sias G, Nkuna M, Ndou N, Hendricks K, Ikebudu V, Koo AJ, Ajayi R, and Iwuoha E. (2023) Seed priming with MeJA prevents salt-induced growth inhibition and oxidative damage in Sorghum bicolor by inducing the expression of jasmonic acid biosynthesis genes. Int. J. Mol. Sci. 24: 10368; doi.org/10.3390/ijms241210368

Kimberlin A, Holtsclaw RE, Zhang T, Mulaudzi T, and Koo AJ. (2022) On the initiation of jasmonate biosynthesis in wounded leaves. Plant Physiol. 189:1925-1942. doi.org/10.1093/plphys/kiac163

Koo AJ and Arimura GI. (2022) Molecular biology of chemical defenses. Plant Mol. Biol. 109:351-353. doi: 10.1007/s11103-022-01290-9. [PubMed]

Kimberlin A, Holtsclaw RE, Zhang T, Mulaudzi T, and Koo AJ. (2022) On the initiation of jasmonate biosynthesis in wounded leaves. Plant Physiol. Apr 11:kiac163. doi: 10.1093/plphys/kiac163. Online ahead of print. [PubMed]

Wang M, Garneau M, Poudel AN, Lamm D, Koo AJ, Bates P, Thelen J. (2022) Overexpression of pea α-carboxyltransferase in Arabidopsis and Camelina increases fatty acid synthesis leading to improved seed oil content. Plant J. 110:1035-1046. doi: 10.1111/tpj.15721. [PubMed]

Kimberlin A, Holtsclaw RE, and Koo AJ. (2021) Differential regulation of the ribosomal association of mRNA transcripts in an Arabidopsis mutant defective in jasmonate-dependent wound response. Front. Plant Sci. 12:637959. doi: 10.3389/fpls.2021.637959. [PubMed]

Fernández-Milmanda GL, Crocco CD, Reichelt M, Mazza CA, Köllner TG, Zhang T, Cargnel MD, Lichy MZ, Koo AJ, Austin AT, Gershenzon J, and Ballaré CL. (2020) A light-dependent molecular link between competition cues 1 and defense responses in plants. Nature Plant 6:223-230. doi: 10.1038/s41477-020-0604-8. [PubMed]

Body MJ, Dave DF, Coffman CM, Paret TY, Koo AJ, Cocroft RB, and Appel HM. (2019) Plant response to insect feeding vibrations involves oxylipin signaling. Front. Plant Sci. 10. doi: 10.3389/fpls.2019.01586. [PubMed]

Poudel AN, Holtsclaw RE, Kimberlin A, Sen S, Zeng S, Joshi T, Lei Z, Sumner LW, Singh K, Matsuura H, and Koo AJ. (2019) 12-Hydroxy-jasmonoyl-L-isoleucine is an active jasmonate that signals through CORONATINE INSENSITIVE 1 and contributes to the wound response in Arabidopsis. Plant Cell Physiol. 60: 2152-2166. doi: 10.1093/pcp/pcz109. [PubMed]

Lunde C, Kimberlin A, Leiboff S, Koo AJ, Hake S. (2019). Tasselseed5 overexpresses a wound-inducible enzyme, ZmCYP94B1, that affects jasmonate catabolism, sex determination, and plant architecture in maize. Commun Biol. 2:114. doi: 10.1038/s42003-019-0354-1. eCollection 2019. [PubMed]

Toyota M, Spencer D, Sawai-Toyota S, Jiaqi W, Zhang T, Koo AJ, Howe GA, Gilroy S. (2018). Glutamate triggers long-distance, calcium-based plant defense signaling. Science. 361(6407):1112-1115. doi: 10.1126/science.aat7744. [PubMed]

Yurchenko O, Kimberlin A, Mehling M, Koo AJ, Chapman KD, Mullen RT, Dyer JM. (2018). Response of high leaf-oil Arabidopsis thaliana plant lines to biotic or abiotic stress. Plant Signal Behav. 13(5):e1464361. doi: 10.1080/15592324.2018.1464361. [PubMed]

Howe GA, Major IT, Koo AJ. (2018). Modularity in Jasmonate Signaling for Multistress Resilience. Annu Rev Plant Biol. 69:387-415. doi: 10.1146/annurev-arplant-042817-040047. [PubMed]

Tripathi D, Zhang T, Koo AJ, Stacey G, Tanaka K. (2018). Extracellular ATP Acts on Jasmonate Signaling to Reinforce Plant Defense. Plant Physiol. 176(1):511-523. doi: 10.1104/pp.17.01477. [PubMed]

Poudel AN, Zhang T, Kwasniewski M, Nakabayashi R, Saito K, Koo AJ. (2016). Mutations in jasmonoyl-L-isoleucine-12-hydroxylases suppress multiple JA-dependent wound responses in Arabidopsis thaliana. Biochim Biophys Acta. 1861(9 Pt B):1396-1408. doi: 10.1016/j.bbalip.2016.03.006. [PubMed]

Schneider A, Aghamirzaie D, Elmarakeby H, Poudel AN, Koo AJ, Heath LS, Grene R, Collakova E. (2016). Potential targets of VIVIPAROUS1/ABI3-LIKE1 (VAL1) repression in developing Arabidopsis thaliana embryos. Plant J. 85(2):305-19. doi: 10.1111/tpj.13106. [PubMed]

Zhang T, Poudel AN, Jewell JB, Kitaoka N, Staswick P, Matsuura H, Koo AJ. (2016). Hormone crosstalk in wound stress response: wound-inducible amidohydrolases can simultaneously regulate jasmonate and auxin homeostasis in Arabidopsis thaliana. J Exp Bot. 67(7):2107-20. doi: 10.1093/jxb/erv521. [PubMed]

Nguyen PD, Pike S, Wang J, Nepal Poudel A, Heinz R, Schultz JC, Koo AJ, Mitchum MG, Appel HM, Gassmann W. (2016). The Arabidopsis immune regulator SRFR1 dampens defences against herbivory by Spodoptera exigua and parasitism by Heterodera schachtii. Mol Plant Pathol. 17(4):588-600. doi: 10.1111/mpp.12304. [PubMed]

Smith JM, Leslie ME, Robinson SJ, Korasick DA, Zhang T, Backues SK, Cornish PV, Koo AJ, Bednarek SY, Heese A. (2014). Loss of Arabidopsis thaliana Dynamin-Related Protein 2B reveals separation of innate immune signaling pathways. PLoS Pathog. 10(12):e1004578. doi: 10.1371/journal.ppat.1004578. eCollection 2014 Dec. [PubMed]

Koo AJ, Thireault C, Zemelis S, Poudel AN, Zhang T, Kitaoka N, Brandizzi F, Matsuura H, Howe GA. (2014). Endoplasmic reticulum-associated inactivation of the hormone jasmonoyl-L-isoleucine by multiple members of the cytochrome P450 94 family in Arabidopsis. J Biol Chem. 289(43):29728-38. doi: 10.1074/jbc.M114.603084. [PubMed]