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Open Access Publications from the University of California

Scholarly Works (5 results)

  • Article
  • Peer Reviewed
UC Riverside Previously Published Works (2018)
Contents Summary 505 I. Introduction 505 II. Models of plant cell division 505 III. Establishing the division plane 506 IV. Maintaining the division plane during mitosis and cytokinesis 509 Acknowledgements 510 References 510 SUMMARY: Plants, a significant source of planet-wide biomass, have an unique type of cell division in which a new cell wall is constructed de novo inside the cell and guided towards the cell edge to complete division. The elegant control over positioning this new cell wall is essential for proper patterning and development. Plant cells, lacking migration, tightly coordinate division orientation and directed expansion to generate organized shapes. Several emerging lines of evidence suggest that the proteins required for division-plane establishment are distinct from those required for division-plane maintenance. We discuss recent shape-based computational models and mutant analyses that raise questions about, and identify unexpected connections between, the roles of well-known proteins and structures during division-plane orientation.
    Cover page: An overview of plant division‐plane orientation
    • Thesis
    • Peer Reviewed
    UC Riverside Electronic Theses and Dissertations (2020)

    The proper organization of the microtubules is a major determinant of cell shape. Microtubule-associated proteins have essential roles in cell shape determination by direct microtubule interaction. During interphase, microtubules populate the cell cortex and are organized perpendicular to the primary axis of growth. During mitosis, microtubules form conserved structures that are essential for the normal completion of cell division. The preprophase band and phragmoplast are plant specific mitotic microtubule structures. TANGLED1 is localized to the division site and guides the expanding phragmoplast during the later stages of mitosis. To understand more about the role of division site localized proteins and their interacting partners on cell shape determination I analyzed microtubule dynamics, cell shape, and localization of TUBULIN and TANGLED1. I characterized an array of microtubules at the cell cortex during telophase. These microtubules were distinct from the phragmoplast and organized perpendicular to the division plane as they interacted with the division site and TANGLED1. The density and organization of microtubules in this array was reduced in tangled1 cells. In wild type cells, we observed individual microtubule addition to the phragmoplast with a preference for the leading edge, however, this preference was lost in tangled1 mutant cells. The asymmetric bundling of telophase microtubules at the cell cortex with phragmoplast microtubules altered the direction of phragmoplast expansion. These findings reveal a novel mechanism for phragmoplast guidance by division site localized proteins. KINECTIN was previously identified as a TANGLED1 interacting protein. We used CRISPR/CAS9 mutagenesis of the kinectin gene region in maize to describe a role for KINECTIN as a potential regulator of microtubule associated proteins in plants. The functional protein domains of KINECTIN were revealed by defects in cell expansion and increased cell shape isotropy in kinectin-1 but not kinectin-2 mutants. Microtubule dynamicity and TANGLED1 accumulation in the spindle were significantly different in kinectin-1 mutant cells. Together, our observations provide additional insight into how proper microtubule organization at the cell cortex determines cell shapes in plants via division plane maintenance and directional cell expansion.

      Cover page: Microtubule Organization at the Cell Cortex is a Determinant of Cell Shape via Division Plane Maintenance and Directional Cell Expansion in Plants
      • Article
      • Peer Reviewed
      UC Riverside Previously Published Works (2015)
      Humans, animals, and plants are constantly under attack from pathogens and pests, resulting in severe consequences on global human health and crop production. Small RNA (sRNA)-mediated RNA interference (RNAi) is a conserved regulatory mechanism that is involved in almost all eukaryotic cellular processes, including host immunity and pathogen virulence. Recent evidence supports the significant contribution of sRNAs and RNAi to the communication between hosts and some eukaryotic pathogens, pests, parasites, or symbiotic microorganisms. Mobile silencing signals—most likely sRNAs—are capable of translocating from the host to its interacting organism, and vice versa. In this review, we will provide an overview of sRNA communications between different kingdoms, with a primary focus on the advances in plant-pathogen interaction systems.
        Cover page: Conversations between kingdoms: small RNAs
        • Article
        • Peer Reviewed
        UC Riverside Previously Published Works (2023)
        Cell divisions are accurately positioned to generate cells of the correct size and shape. In plant cells, the new cell wall is built in the middle of the cell by vesicles trafficked along an antiparallel microtubule and a microfilament array called the phragmoplast. The phragmoplast expands toward a specific location at the cell cortex called the division site, but how it accurately reaches the division site is unclear. We observed microtubule arrays that accumulate at the cell cortex during the telophase transition in maize (Zea mays) leaf epidermal cells. Before the phragmoplast reaches the cell cortex, these cortical-telophase microtubules transiently interact with the division site. Increased microtubule plus end capture and pausing occur when microtubules contact the division site-localized protein TANGLED1 or other closely associated proteins. Microtubule capture and pausing align the cortical microtubules perpendicular to the division site during telophase. Once the phragmoplast reaches the cell cortex, cortical-telophase microtubules are incorporated into the phragmoplast primarily by parallel bundling. The addition of microtubules into the phragmoplast promotes fine-tuning of the positioning at the division site. Our hypothesis is that division site-localized proteins such as TANGLED1 organize cortical microtubules during telophase to mediate phragmoplast positioning at the final division plane.
          Cover page: Cortical microtubules contribute to division plane positioning during telophase in maize
          • Article
          • Peer Reviewed
          UC Davis Previously Published Works (2023)
          INTRODUCTION: During proliferative plant cell division, the new cell wall, called the cell plate, is first built in the middle of the cell and then expands outward to complete cytokinesis. This dynamic process requires coordinated movement and arrangement of the cytoskeleton and organelles. METHODS: Here we use live-cell markers to track the dynamic reorganization of microtubules, nuclei, endoplasmic reticulum, and endomembrane compartments during division and the formation of the cell plate in maize leaf epidermal cells. RESULTS: The microtubule plus-end localized protein END BINDING1 (EB1) highlighted increasing microtubule dynamicity during mitosis to support rapid changes in microtubule structures. The localization of the cell-plate specific syntaxin KNOLLE, several RAB-GTPases, as well as two plasma membrane localized proteins was assessed after treatment with the cytokinesis-specific callose-deposition inhibitor Endosidin7 (ES7) and the microtubule-disrupting herbicide chlorpropham (CIPC). While ES7 caused cell plate defects in Arabidopsis thaliana, it did not alter callose accumulation, or disrupt cell plate formation in maize. In contrast, CIPC treatment of maize epidermal cells occasionally produced irregular cell plates that split or fragmented, but did not otherwise disrupt the accumulation of cell-plate localized proteins. DISCUSSION: Together, these markers provide a robust suite of tools to examine subcellular trafficking and organellar organization during mitosis and cell plate formation in maize.
            Cover page: Subcellular positioning during cell division and cell plate formation in maize.
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