Dr. Kyaw (Joe) Aung received his BS and MS in Horticulture from National Chung Hsing University, Taiwan. He completed his PhD from Michigan State University (MSU) under the guidance of Dr. Jianping Hu. Prior his research journey at MSU, he was a Research Assistant in the Agricultural Biotechnology Research Center at Academia Sinica, Taiwan, with Dr. Tzyy-Jen Chiou. Dr. Aung later conducted his postdoctoral research at MSU with Dr. Sheng Yang He, where he examined plant-microbe interactions. In 2018, Dr. Aung joined the faculty of the Genetics, Development, and Cell Biology Department as an Assistant Professor.
A hallmark of multicellular organisms is their ability to maintain physiological homeostasis by communicating among cells, tissues, and organs. In plants, intercellular communication is largely dependent on plasmodesmata (PD), which are membrane-lined channels connecting adjacent plant cells. In our laboratory, we are broadly interested in understanding how plants harness intercellular communication to maintain homeostasis in the regulation of growth and defense. Our long-term research goal is to determine the underlying mechanisms regulating cell-to-cell communication in plants to engineer climate-resilience crops for future agriculture.
Regulation of PD function at specific cell interfaces
Different cell types have evolved specialized functions to effectively support a multicellular organism to operate as a unit. Cells need to maintain their own cellular identity while effectively communicating with surrounding cells and tissues. It has been well established that the plant polysaccharide callose (ß-1,3-glucan) is deposited at PD, regulating the PD aperture; however, the regulation of PD at different cell interfaces is largely unknown. PD-located proteins (PDLPs) regulate callose accumulation at PD through unknown mechanisms. The Arabidopsis genome encodes eight members of PDLPs, sequentially named PDLP1-8. Our recent findings showed that PDLP5 and PDLP6 are expressed in non-overlapping cell types. The constitutive overexpression of PDLP5 and PDLP6 results in the overaccumulation of callose at PD at different cell interfaces, indicating their functional specificities in different cell types. Our studies begin to reveal that PDLPs play a major role in regulating PD function at specific cell interfaces. We will further investigate the cell type-specific function of other PDLPs in Arabidopsis.
PD function as signaling hubs
To determine the molecular function of PDLPs, we performed a proximity labeling (PL) approach. We showed that the PL assay is a powerful tool to map PD proteomes at nanometer resolution. We identified several putative functional partners of PDLP5. Among the candidate proteins, we are focusing on determining the molecular function of several Leucine-Rich Repeats Receptor-Like Kinases (LRR-RLKs) and Cysteine-Rich Receptor-Like Kinases (CRKs). Since LRR-RLKs and CRKs are known to involve in signal perception and transduction, PDLP5 might recruit them to form signaling hubs at PD. We will employ a combination of molecular, cellular, genetic, and biochemical approaches to determine the role of PD as major signaling hubs in regulating local and long-distance cell communication.
Dynamic regulation of PD during bacterial infection
Plants trigger PD closure upon microbial infection, activating PD immunity. To overcome PD immunity, microbial pathogens inject protein effectors into plant cells to target PD. The findings suggest that PD are dynamically regulated at different stages of microbial infections. To better understand the role of PD during plant immunity, we study the Arabidopsis thaliana-Pseudomonas syringae pathosystem. We utilized the PL assay to capture the changes in PDLP5-containing protein complexes upon bacterial infection. We identified a set of candidate proteins with potential roles in regulating PD function during bacterial infection. We are determining the molecular function of candidate proteins in regulating PD function and plant immunity. We will further utilize the PL assay to capture the dynamic changes in PDLP5-functional protein complexes at different stages of bacterial infection.
Li Z, Liu, S, Montes, C., Walley, J.W., and Aung K (2022) Plasmodesmata-located proteins regulate plasmodesmal function at specific cell interfaces in Arabidopsis. bioRxiv. https://doi.org/10.1101/2022.08.05.502996.
Li Z, Variz H, Chen Y, Liu S, and Aung K (2021) Plasmodesmata-dependent intercellular movement of bacterial effectors. Front.Plant Sci. doi: 10.13389/fpls.2021.640277.
Van Stan J, Morris C, Aung K, Kuzyakov Y, Magyar D, Rebollar E, Remus-Emsermann M, Uroz S, and Vandenkoornhuyse (2020) Precipitation partitioning – Hydrologic highways between microbial communities of the plant microbiome? Precipitation Partitioning by Vegetation. Springer 229-252.
Aung K*, Kim P, Li Z, Joe A, Kvitko B, Alfano J, and He S (2020) Pathogenic bacteria target plant plasmodesmata to colonize and invade surrounding tissues. Plant Cell. DOI: https://doi.org/10.1105/tpc.19.00707. *: co-corresponding author.
Aung K*, Jiang Y, and He S* (2018) The role of water homeostasis in plant-microbe interactions. Plant J 93: 771-780. *: co-corresponding author.
Aung K, Xin X, Mecey C, and He S (2017) Subcellular localization of Type III secretion proteins in plants. Methods Mol Biol.1531: 141-153.
Xin X, Nomura K, Aung K, Velásquez A, Yao J, Boutrot F, Chang J, Zipfel C, and He S (2016) Bacteria establish an aqueous living space as a crucial virulence mechanism. Nature 539: 524-529.
Xin X, Nomura K, Ding X, Chen X, Wang K, Aung K, Uribe F, Rosa B, Yao J, Chen J, and He S (2015) Pseudomonas syringaeeffector avirulence protein localizes to the host plasma membrane and down-regulates the expression of the NONRACE-SPECIFIC DISEASE RESISTANCE1/HARPIN-INDUCED1-LIKE13 gene required for antibacterial immunity in Arabidopsis. Plant Physiol 169: 793-802.
Aung K, Kaur N, and Hu J (2014) Dynamin-related proteins in peroxisome division. In: Molecular machines involved in peroxisome biogenesis and maintenance, Editors: Brocard C and Hartig A. Springer 439-460.
Chen Y, Aung K, Rolčík J, Walicki K, Friml J, and Brandizzi F (2014) Inter-regulation of the unfolded protein response and auxin signaling. Plant J 77: 97-107.
Quan S, Yang P, Cassin-Ross G, Kaur N, Switzenberg R, Aung K, Li J, and Hu J (2013) Proteome analysis of peroxisomes from etiolated Arabidopsis seedlings identifies a peroxisomal protease involved in beta-oxidation and development. Plant Physiol 163: 1518-1538.
Aung K and Hu J (2012) Differential roles of Arabidopsis dynamin-related proteins DRP3A, DRP3B, and DRP5B in organelle division. J Integr Plant Biol 54 (11): 921-931.
Aung K and Hu J (2011) The Arabidopsistail-anchored coiled-coil protein PEROXISOMAL AND MITOCHONDRIAL DIVISION FACTOR1 is involved in the morphogenesis and proliferation of peroxisomes and mitochondria. Plant Cell 23: 4446-4461.
Liu T, Aung K, Tseng C, Chang T, Chen Y, and Chiou T (2011) Vacuolar Ca2+/H+transport activity is required for systemic phosphate homeostasis involving shoot-to-root signaling in Arabidopsis. Plant Physiol 156: 1176-1189.
Aung K, Zhang X, and Hu J (2010) Peroxisome division and proliferation in plants. Biochem Soc Trans 38: 817-822.
Aung K and Hu J (2009) The Arabidopsis peroxisome division mutant pdd2is defective in the DYNAMIN-RELATED PROTEIN3A (DRP3A) gene. Plant Signal Behav 4(6): 542-544.
Reumann S, Quan S, Aung K, Yang P, Manandhar-Shrestha K, Holbrook D, Linka N, Switzenberg R, Wilkerson CG, Weber APM Olsen LJ, and Hu J (2009) In-depth proteome analysis of Arabidopsis leaf peroxisomes combined with in vivo subcellular targeting verification indicates novel metabolic and regulatory functions of peroxisomes. Plant Physiol 150: 125-143.
Aung K*, Lin S*, Wu C, Huang Y, Chiang S, and Chiou T (2006) pho2, a phosphate over-accumulator, is caused by a nonsense mutation in the miR399 target gene. Plant Physiol 141(3): 1000-1011. *: equally contributed.
Chiou T, Aung K*, Lin S*, Wu C*, Chiang S, and Su C (2006) Regulation of phosphate homeostasis by microRNA in Arabidopsis. Plant Cell 18(2): 412-421. *: equally contributed.
Fujii H, Chiou T, Lin S, Aung K, and Zhu J (2005) A miRNA involved in phosphate-starvation response in Arabidopsis. Current Biology 15: 2038-2043.