Seminar: Regulation of plasmodesmata during defense and development

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Date/Time:Friday, 11 Feb 2022 from 4:10 pm to 5:00 pm
Location:1414 Molecular Biology
Cost:Free
Contact:Danise Jones
Phone:515-294-2687
Channel:Research
Categories:Lectures
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Join this seminar to hear about research looking at the plasmodesmata pathway regulation in plant cells. The many techniques and tolls used to study these pathways will be discussed, as well as where the future research may go.

Join this Genetics, Development and Cell Biology seminar to hear from Dr. Joe (Kyaw) Aung, assistant professor in Genetics, Development and Cell Biology at Iowa State University, discuss his research into the plasmodesmata pathways.

Abstract: 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 aim to understand the regulation and function of PD during defense and development. Given that PD function as membrane conduits, plasmodesmal aperture determines their function. It is well documented that callose (ß-1,3-glucan) is deposited at PD within cell walls to restrict plasmodesmal aperture. Plasmodesmata-located proteins (PDLPs) are known to positively regulate callose accumulation at PD through an unknown mechanism. We recently reported that a pathogenic bacterium utilizes a protein effector HopO1-1 to manipulate the function of PD. HopO1-1 physically interacts with and destabilizes PDLP5 and PDLP7. We also reported that other bacterial effector proteins can move from infected plant cells to adjoining plant cells through PD. Our findings begin to reveal how pathogenic bacteria regulate and utilize PD to promote diseases. During development, PD have been implicated their roles in allowing sugars to move from photosynthetic mesophyll cells to phloem for sugar loading in mature leaves, distributing sugars from photosynthetic tissues to non-photosynthetic tissues. We observed that PDLP5 and PDLP6 express in and function at different cell types. Overexpression of PDLP5 and PDLP6 results in overaccumulation of callose at PD and blocks the movement of sugars at different cell-cell interfaces in leaves. Our findings begin to reveal cell type-specific roles of PDLPs in regulating the PD function. To identify functional partners of PDLP5 and PDLP6, we conducted an enzyme-catalyzed proximity labeling (PL) assay. We identified several known and putative PD-localized proteins as well as proteins with unknown function in regulating PD. We further demonstrated that PDLP6 physically and genetically interacts with sucrose synthases 6 (SuSy6) and callose synthase 7 (CalS7). We hypothesize that PDLP6-SuSy6-CalS7 is a part of callose synthase complex, which functions specifically in sieve element and regulates sugar loading in phloem. The findings provide empirical evidence on the role of PD in allowing sugar to move symplastically from photosynthetic cells to phloem. We also demonstrate the power of a PL assay in investigating plasmodesmal biology.