Plasmodesmata: composition, structure and trafficking

Abstract

Plasmodesmata are highly specialized gatable trans-wall channels that interconnect contiguous cells and function in direct cytoplasm-to-cytoplasm intercellular transport. Computer-enhanced digital imaging analysis of electron micrographs of plasmodesmata has provided new information on plasmodesmatal fine structure. It is now becoming clear that plasmodesmata are dynamic quasi-organelles whose conductivity can be regulated by environmental and developmental signals. New findings suggest that signalling mechanisms exist which allow the plasmodesmatal pore to dilate to allow macromolecular transport. Plant viruses spread from cell to cell via plasmodesmata. Two distinct movement mechanisms have been elucidated. One movement mechanism involves the movement of the complete virus particle along virus-induced tubular structures within a modified plasmodesma. Apparently two virus-coded movement proteins are involved. A second movement mechanism involves the movement of a non-virion form through existing plasmodesmata. In this mechanism, the viral movement protein causes a rapid dilation of existing plasmodesmata to facilitate protein and nucleic acid movement. Techniques for the isolation of plasmodesmata have been developed and information on plasmodesma-associated proteins is now becoming available. New evidence is reviewed which suggests that plasmodesmatal composition and regulation may differ in different cells and tissues.

Live cell imaging reveals extensive intracellular cytoplasmic colonization of banana by normally non-cultivable endophytic bacteria

“…It is a priority task now to elucidate how the organisms gain access to the intracellular niche. Plasmodesmata are too small to allow the cell-to-cell movement of bacteria, unlike viruses (Epel 1994; Evert 2006). Endophytic bacteria are known to bear cellulolytic enzymes facilitating their selective recruitment by the host from environmental flora discriminating from potential plant pathogens (Rosenblueth and Martinez-Romero 2006; Compant et al 2010).…”

Plasmodesmata during development: re-examination of the importance of primary, secondary, and branched plasmodesmata structure versus function

“…These data have led to the idea that TMV-MP only localizes to complex branched PD with central cavities, called “secondary” PD by the authors, in mature tissues (Ding et al 1992). Many reports have subsequently asserted that viral MPs preferentially localize to “secondary” plasmodesmata in mature tissues (e.g., Epel 1994; Hofius et al 2001). Based on these earlier reports, TMV-MP was used to distinguish branched (“secondary”) PD from primary PD (Roberts et al 2001).…”

Cell-Cell Communication in the Tumor Microenvironment, Carcinogenesis, and Anticancer Treatment

“…Connexins (gap junctions), comparable to Plasmodesmata in plants, are tube-forming protein complexes found between intracellular compartments in animals [6]. They provide a direct connection between the cytoplasm of one cell and the cytoplasm of an adjacent cell, allowing a flow of molecules along concentration gradients between connected cells when open, but blocking the flow without delay when closed [7].…”