Quantification of symplastic continuity as visualised by plasmodesmograms: diagnostic value for phloem-loading pathways

• Published in: Planta 1992-06, Vol.187 (3), p.359-366
• Main Authors: Botha, C.E.J, Bel, A.J.E. van
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Bromus catharticus; Bundle sheath cells; Cell physiology; Cell walls; Eragrostis plana; Fundamental and applied biological sciences. Psychology; Magnoliopsida; Mesophyll; Mesophyll cells; Panicum maximum; Parenchyma; Phloem; phloem loading; Plant cells; Plant physiology and development; Plant veins; plants; Plasma membrane and permeation; Plasmodesmata; Populus deltoides; quantitation; Sieve tubes; spatial distribution; symplast; Themeda triandra; themeda triandra var. imberbis; transport
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/BF00195659

The use of plasmodesmatal frequency to correlate cell-cell symplastic transport capacity remains a contentious problem, as variation in cell shape, accurate determination of interface contact area between cell types, distribution (i.e. whether random or aggregated) and shape (i.e. whether single or branched), and state of permeability may confuse the issue. Additionally, variation in the methods used to determine the frequencies compounds the problem further. Data presented in this paper show that plasmodesmograms offer a means to visualise the potential transport pathway from mesophyll cells to sieve tubes. Furthermore, the results allow an instant appreciation of symplastic continuity or discontinuity and, accordingly, the potential symplastic and/or apoplastic stages involved in the overall loading process.