鄭惠國 (Teh, Ooi-Kock)
- 2016-2021 Assistant Professor, Hokkaido University, Japan
- 2015-2016 Postdoctoral Researcher, IPB, Halle, Germany
- 2013-2015 Postdoctoral Researcher, SLU, Sweden
- 2010-2013 JSPS Research Fellow, Kyoto University, Japan
- 2007-2010 Research Officer, Malaysian Palm Oil Board, Malaysia
- 2003-2007 D.Phil Department of Plant Sciences, University of Oxford
- 2000-2003 B.Sc. Faculty of Science, Universiti Malaya
- Bryophytes, cell biology, developmental biology, Physcomitrium patens
- Lab Website
Size and shape are fundamental features of living things and they vary a great deal (think an ant vs an elephant), often reflecting their evolutionary adaptations to selection pressure. The same morphological diversity is equally prevalent in the plant kingdom (think duckweeds vs. Rafflesia flower). We are interested in understanding molecular factors and mechanisms that contribute to this morphological divergence. In another words, we want to find out what makes the plants look the way they are. For this purpose, we use different plants such as bryophytes (small non-vascular plants) that represent the sister group of early diverging plants and Arabidopsis thaliana (a small vascular flowering plant) as models to investigate how size and shape are regulated and determined in plants. Comparing regulatory mechanism of these features in different plant models enables us to have a glimpse into the evolution-development (evo-devo) aspects of land plant evolution.
Shape: When plants first colonised the dry land, they invented an important trick to transform their simple body plan to the extended root system that we observe in the land plants now. This newly invented feature allows the land plants to have better access to nutrients and firmer anchorage to the soil. This new trick, termed polarised/apical tip growth, is commonly observed in root hairs and pollen tubes, and allows protrusion from a cell to take place at a defined location, with continuous and rapid growth concentrated at the tip. We recently discovered small signalling peptides from the moss Physcomitrium patens that are necessary to facilitate apical tip growth in the protonemata, a filamentous gametophytic structure. These signalling peptides, termed Rapid Alkalinisation Factors (RALFs), are a type of hundreds (if not thousands) of signalling peptides found in plants and are necessary to relay signalling information during developmental processes. In moss mutants that lack some of these RALFs, we found that protonemata cell length was significantly reduced. We are trying to figure out what signalling process RALFs communicate to the cells during the apical tip growth.
The edge of wild type (WT) colonies shows rough/hairy edge (a, c) while the ralf moss mutant displays a smooth edge which is due to the reduced caulonemata elongation (b, d). The RALF protein is localised to the growing tip in chloronemata (e) as well as in the elongating protoplasts (f-h).
Size: The sizes of organisms are determined either by the cell size or the number of cells. While some organisms such as the nematode C. elegans develops to contain precisely 1031 cells in males and 959 cells in hermaphrodites, plants with a fixed cell number are rare due to their cellular plasticity conferred by pools of stem cells. Indeed, the great size variations between different tomatoes and bell peppers are due to the cell numbers, not the cell size as the cell size remains relatively constant. This indicates that the plants can maintain the cell size and make sure the cells only divide after they grow to a right size. How do plants achieve this? Since cell sizes are intimately linked to the cell division mechanisms, we are interested in deciphering negative determinants that suppress cell cycle progression. We hypothesise that an autophagy-dependent degradation helps to remove cell cycle suppressors and provides clearance for cell division to proceed.
In our hypothesis, cell cycle inhibitors (circles marked with —) are distributed throughout the cell as it grows. When the cell grows to a predetermined size, this triggered the autophagy-dependent degradation of these inhibitors in the vacuole.
Our lab uses combinatory approaches of genetics, cell biology, biochemistry and big data analyses to solve these fundamental questions in developmental biology.
We are always looking for potential collaboration and outstanding candidates to join our laboratory at various levels (Postdoc, PhD and master students). If you share the same research interest as mine, please feel free to get in touch and see if we could work on some exciting projects together.
Selected publication list
- Brillada C*, Teh OK*, Ditengou FA, Lee CW, Klecker T, Saeed B, Furlan G, Zietz M, Hause G, Eschen-Lippold L, Hoehenwarter W, Lee J, Ott T, Trujillo M. (2021) Exocyst subunit Exo70B2 is linked to immune signaling and autophagy. Plant Cell. Apr 17;33(2):404-419. doi: 10.1093/plcell/koaa022. *Co-first authorship
- Do TH, Pongthai P, Ariyarathne M, Teh OK, Fujita T. (2020) AP2/ERF transcription factors regulate salt-induced chloroplast division in the moss Physcomitrella patens. J Plant Res. Jul;133(4):537-548. doi: 10.1007/s10265-020-01195-y.
- Teh OK, Lee CW, Ditengou FA, , Klecker T, Furlan G, Zietz M, Hause G, Eschen-Lippold L, Hoehenwarter W, Lee J, Ott T, Trujillo M. (2019) Phosphorylation of the exocyst subunit Exo70B2 contributes to the regulation of its function. bioRxiv doi: https://doi.org/10.1101/266171.
- Shimada T, Fuji K, Ichino T, Teh OK, Koumoto Y, Hara-Nishimura I. (2018) GREEN FLUORESCENT SEED, to Evaluate Vacuolar Trafficking in Arabidopsis Seeds. Methods Mol Biol. 1789:1-7. doi: 10.1007/978-1-4939-7856-4_1.
- Liu H, Ravichandran S, Teh OK, McVey S, Lilley C, Teresinski HJ, Gonzalez-Ferrer C, Mullen RT, Hofius D, Prithiviraj B, Stone SL. (2017) The RING-Type E3 Ligase XBAT35.2 Is Involved in Cell Death Induction and Pathogen Response. Plant Physiol. Nov;175(3):1469-1483. doi: 10.1104/pp.17.01071.
- Teh OK, Hatsugai N, Tamura K, Fuji K, Tabata R, Yamaguchi K, Shingenobu S, Yamada M, Hasebe M, Sawa S, Shimada T, Hara-Nishimura I. (2015) BEACH-domain proteins act together in a cascade to mediate vacuolar protein trafficking and disease resistance in Arabidopsis. Mol Plant. Mar;8(3):389-98. doi: 10.1016/j.molp.2014.11.015.
- Munch D*, Teh OK*, Malinovsky FG*, Liu Q, Vetukuri RR, El Kasmi F, Brodersen P, Hara-Nishimura I, Dangl JL, Petersen M, Mundy J, Hofius D. (2015) Retromer contributes to immunity-associated cell death in Arabidopsis. Plant Cell. Feb;27(2):463-79. doi: 10.1105/tpc.114.132043. *Co-first authorship
- Teh OK, Hofius D. (2014) Membrane trafficking and autophagy in pathogen-triggered cell death and immunity. J Exp Bot. Mar;65(5):1297-312. doi: 10.1093/jxb/ert441.
- Teh OK, Shimono Y, Shirakawa M, Fukao Y, Tamura K, Shimada T, Hara-Nishimura I. (2013) The AP-1 μ adaptin is required for KNOLLE localization at the cell plate to mediate cytokinesis in Arabidopsis. Plant Cell Physiol. Jun;54(6):838-47. doi: 10.1093/pcp/pct048.
- Teh OK, Ramli US. (2011) Characterization of a KCS-like KASII from Jessenia bataua that elongates saturated and monounsaturated stearic acids in Arabidopsis thaliana. Mol Biotechnol. Jun;48(2):97-108. doi: 10.1007/s12033-010-9350-x.
- Teh OK, Moore I. (2007) An ARF-GEF acting at the Golgi and in selective endocytosis in polarized plant cells. Nature. Jul 26;448(7152):493-6. doi: 10.1038/nature06023.