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Arabidopsis MAP65-4 plays a role in phragmoplast microtubule organization and marks the cortical cell division site

Haoge Li1,2, Baojuan Sun2,3, Michiko Sasabe4

  • 1College of Biological Science and Technology, Shenyang Agricultural University, Shenyang, Liaoning, 110866, China.

The New Phytologist
|April 4, 2017
PubMed

Insights

Microtubule-associated protein MAP65-3 and MAP65-4 exhibit redundant functions in plant cell division. MAP65-4 compensates for MAP65-3 loss, ensuring proper microtubule organization and cytokinesis.

Area of Science:

  • Plant Cell Biology
  • Molecular Plant Science
  • Cytoskeletal Dynamics

Background:

  • Microtubule-associated proteins (MAPs) are crucial for microtubule organization.
  • The MAP65 family bundles anti-parallel microtubules (MTs).
  • MAP65-3 mutations in Arabidopsis thaliana disrupt phragmoplast MT organization and cause cytokinesis failure, but other MAP65 functions remain unclear.

Purpose of the Study:

  • To investigate the functions of other Arabidopsis MAP65 isoforms, specifically MAP65-4.
  • To elucidate the genetic interactions and functional redundancy between MAP65-3 and MAP65-4.
  • To understand the dynamic localization and roles of MAP65-4 during cell division.

Main Methods:

  • Genetic analysis of map65 mutations, including synthetic lethality and suppression assays.
  • Live-cell imaging to observe dynamic protein localization.
  • Immunolocalization experiments to determine protein distribution during mitosis and cytokinesis.

Main Results:

  • map65-4 mutation caused synthetic lethality with map65-3, indicating functional interaction.
  • Overexpression of MAP65-4 suppressed map65-3 defects, restoring MT engagement in the spindle midzone and improving cytokinesis and seedling growth.
  • MAP65-4 localizes to the preprophase band, cortical division site, spindle midzone, and phragmoplast, with enhanced phragmoplast localization in the absence of MAP65-3.

Conclusions:

  • MAP65-3 and MAP65-4 have redundant yet distinct roles in bundling anti-parallel MTs within the phragmoplast.
  • MAP65-4 plays a novel role at the cortical cell division site.
  • Functional redundancy and specific localization patterns highlight the complex regulation of plant cytokinesis by MAP65 proteins.
Keywords:
Arabidopsis thalianacell division sitecytokinesismicrotubule-associated proteinmicrotubules (MTs)phragmoplast

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