Localization of a myosin‐like protein to plasmodesmata

Abstract

SummaryMyosin has been localized to plasmodesmata in root tissues of Allium cepa, Zea mays and Hordeum vulgare using a polyclonal antibody to animal myosin in both fluorescence and electron microscopy. Labelling was also observed throughout the cytoplasm, mainly associated with the endoplasmic reticulum and plasma membrane. On Western blots, bands of 180 and 110 kDa were consistently labelled in all three species. These bands were also labelled when the blot was incubated in actin prior to staining with antibodies to actin, raising the possibility that either of these proteins (180 kDa or 110 kDa) may be present in plasmodesmata. Pre-treatment of the tissue with 2,3-butanedione monoxime (BDM), an inhibitor of actin-myosin motility, resulted in a strong constriction of the neck region of plasmodesmata. These results indicate that a myosin-like protein may be present in plasmodesmata and may also play a role in the regulation of transport at the neck region.

RETRACTED: Arabidopsis myosin XI mutant is defective in organelle movement and polar auxin transport

“…Whereas many of these functions could be experimentally determined by knockout experiments, to our knowledge no loss-of-function mutation for myosins from the plant kingdom has yet been published. Knowledge about roles of actomyosin often comes from inhibitor studies (9-10) or immunolocalization with cross-reacting antibodies against animal myosins (11)(12)(13)(14), suggesting functions in cytoplasmic streaming and organelle movement, as well as plasmodesmata. The use of antibodies with more defined specificity has been realized in only a few studies.…”

Functional Analysis of a DNA-Shuffled Movement Protein Reveals That Microtubules Are Dispensable for the Cell-to-Cell Movement of Tobacco mosaic virus

“…It is well established that the cortical ER system is dynamic (Allen and Brown, 1988;Hepler et al, 1990;Grabski, 1993;Cantrill et al, 1999), and actin has been implicated in cortical ER movements (Quader et al, 1987) as well as in providing a "scaffold" for trafficking ER-associated Golgi stacks (Boevink et al, 1996). Inhibitors of the actin cytoskeleton increase the size exclusion limit of plasmodesmata (Ding, 1996), and actin and myosin have been immunolocalized to plasmodesmata (White et al, 1994;Radford and White, 1998;Baluska et al, 2000). Therefore, we suggest that future studies address the role of actin as a potential cytoskeletal element for transporting ER-bound vRNA complexes to, and through, higher plant plasmodesmata.…”

Organelle–nucleus cross-talk regulates plant intercellular communication via plasmodesmata

“…These proteins regulate PD aperture and transport by either depositing or removing callose from the cell walls surrounding PD openings. PD also contain cytoskeleton-associated proteins, including actin (7) and myosin (8). Proteins with potential roles in signal transduction are also PD constituents, such as a calcium kinase (9), calreticulin (10), a kinase that phosphorylates viral movement proteins (11), and membrane receptor-like proteins [PD-localized proteins (PDLPs)] (12).…”