In plant cytokinesis, a process fundamentally different from cytokinesis in animals, de novo formation of a cell plate that is maturing into a new cell wall partitions the cytoplasm of the dividing cell. The development of new cell walls during division is of profound importance to all plant life on earth, yet fundamental questions remain unanswered. Understanding this fundamental plant process will help maintain plant biomass and consistent yield. Because cytokinesis is a choreographed abstract concept, we developed an animation for accessibility scientific community and for educational purposes.
We developed a biophysical model, demonstrating that a spreading force generated by the polysaccharide callose is essential for the completion of cytokinesis. We validated the model by pharmacological inhibition of callose deposition, using Endosidin 7 (ES7), a chemical we characterized in our lab. Our study can have a wide application on how membrane structures evolve and will shed light on such transitions that occur beyond cytokinesis, in both plant and animal systems.
Exploring advances in light microscopy and lattice light sheet microscopy LLSM, we studied the entire process of the cell plate development across four dimensions (4D), from its first emergence, via cytokinesis specific GTPase YFP-RABA2a vesicles to the completed cell wall. We identified three distinct and trackable, cell plate developmental phases, that can be used to study cell plate development. The phase transition between phase I and II is striking, indicating a switch from membrane accumulation to the recycling of excess membrane material). Further, through treatment with ES7 we suppressed phase transitions, establishing the critical role and timing of callose deposition in cell plate expansion and maturation. Using these tools we are now characterizing the biological role of candidate proteins involved in cell plate development.
Taking advantage of the freshwater alga Penium margaritaceum, with a cell wall composition similar that of land plants, we investigate the evolutionary role of cytokinetic callose in this unicellular alga.
Using a combination of vesicle proteomic/glycomic analyses we identified both protein and polysaccharide cargo transported through the trans-Golgi network. This will allow us to investigate how glycans, while in the endomembrane system, change during plant development or in response to environmental stimuli. We identified many new components/players and we are currently investigating their biological role in plant development and plant stress response. One of these players is AtTRAPPC11.
In our current ongoing research utilizing genetics, vesicle proteomics and transcriptomics we have identified candidate proteins essential for completion of cytokinesis and hormonal signaling for which we are characterizing their biological function.
In these interdisciplinary endeavors we collaborate with scientists at UC Davis (Dr. Cox, Physics; Dr. Comai, Dr. N Shabek Plant Biology, Dr Holman (LBNL) and U of Utah (Dr. Iwasa).