Cell-cell communication in the leaves of Commelina cyanea and other plants

Abstract

The fiuorescent probes 6-carboxylluorcscein and lucifer yellow CH which do not pass the plastnalemma have been used to examine cell-to-ccU cotnmunication in the \sai oi Commelina cyanea. Dye movement from ccll-to-cell occurs in epidermal, spongy and palisade mesophyll, and vascular cells. Dye movement between these tissues was also found. Hence, the epidermis, spongy and palisade mesophyll cells, and vascular tissue are all linked in a continuous symplast. However, dye injected into the epidermal cells rarely moves into guard cells, indicating that these cells are relatively isolated from the surrounding cells. In the same way, guard cells in Vicia faint and the C4 grass Anthephora pubescens also appeared to be isolated from epidertnal cells. Thus guard cell isolation frotn cell-to-cell communication appears to be a comtnon phenomenon. Hence, the ion fluxes required for guard cell function must occur via the apoplast.

Developmental Regulation of Intercellular Protein Trafficking through Plasmodesmata in Tobacco Leaf Epidermis

“…Targeting of 3a MP:GFP to truncated plasmodesmata between the epidermal and mature guard cells was unexpected, because these plasmodesmata apparently do not have intercellular transport functions (Erwee et al, 1985;Palevitz and Hepler, 1985;Ding et al, 1997). Nevertheless, this finding implies that protein targeting to plasmodesmata is an autonomous function of a cell and is not necessarily coupled to protein translocation through plasmodesmata or protein release from plasmodesmata for import into a neighboring cell.…”

The Evidence for Symplastic Phloem Loading

“…Erwee et al (9) and Madore et al (22) examined tissue in which the lower epidermis was removed but the spongy mesophyll remained and obscured the veins; dye was seen to travel in the direction of the veins, but the cell type(s) carrying the dye could not be identified. Van Does dye-coupling indicate that phloem loading is symplastic?…”

Quantification of Apoplastic Potassium Content by Elution Analysis of Leaf Lamina Tissue from Pea (Pisum sativum L. cv Argenteum)

“…It was concluded that the mesophyll apoplast in pea has a relatively low capacitance as an ion reservoir. Apoplastic K+ content was found to be highly sensitive to changes in xylem solution concentration.The apoplast within leaf tissue constitutes a potentially important pathway for K+ transport between vascular and mesophyll tissues (6,22,23) accumulate extracellulary within the vascular bundles, whereas lower concentrations would exist within the cell wall of mesophyll tissue more distant from the minor veins.The specific role(s) ofthe apoplast as related to K+ transport and accumulation within leaf lamina tissue cannot be fully elucidated without quantitative analysis of extracellular K+ content and concentration (20). Several indirect approaches have been reported for collection of apoplastic sap and estimation of ionic concentrations including analysis of xylem exudates, vacuum perfusion of leaf lamina discs (1), and pressure dehydration of leaves (14).…”

“…The apoplast within leaf tissue constitutes a potentially important pathway for K+ transport between vascular and mesophyll tissues (6,22,23) accumulate extracellulary within the vascular bundles, whereas lower concentrations would exist within the cell wall of mesophyll tissue more distant from the minor veins.…”

“…The apoplast within leaf tissue constitutes a potentially important pathway for K+ transport between vascular and mesophyll tissues (6,22,23) as well as an extracellular ion reservoir influencing absorption and accumulation into individual cells (8,25). The apoplastic compartment comprises mature xylem, due to the lack of a functional plasma membrane, and a continuum of interconnecting cell walls within mesophyll tissue.…”