ArticlePlant physiology2006
Phloem loading in two Scrophulariaceae species. What can drive symplastic flow via plasmodesmata?
Article in Plant physiology, 2006. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 40 papers.
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Who cites it
40 citing papers in PubMed, 87 citations in OpenAlex.
- Microscopic probing into plasmodesmata (PD) and PD-derived intercellular gateways (PdIGs): Beyond morphology.Protoplasma · 2026Review
- Measurement of Subcellular Metabolite Concentrations in Relation to Phloem Loading.Methods in molecular biology (Clifton, N.J.) · 2026Article
- Potassium stimulates fruit sugar accumulation by increasing carbon flow inHorticulture research · 2024Article
- Significance of Raffinose Family Oligosaccharides (RFOs) metabolism in plants.Advanced biotechnology · 2024Review
- Plant Heterotrophic Cultures: No Food, No Growth.Plants (Basel, Switzerland) · 2024Review
- Sucrose Metabolism and Transport in Grapevines, with Emphasis on Berries and Leaves, and Insights Gained from a Cross-Species Comparison.International journal of molecular sciences · 2021Review
- Leaf Epidermis: The Ambiguous Symplastic Domain.Frontiers in plant science · 2021Article
- Critical Phenological Events Affect Chemical Defense of Plant Tissues: Iridoid Glycosides in a Woody Shrub.Journal of chemical ecology · 2020Article
- Non-structural Carbohydrate Metabolism in the Flesh of Stone Fruits of the GenusFrontiers in plant science · 2020Review
- SlSWEET1a is involved in glucose import to young leaves in tomato plants.Journal of experimental botany · 2019Article
- Similar photosynthetic response to elevated carbon dioxide concentration in species with different phloem loading strategies.Photosynthesis research · 2018Article
- Article
- Phloem Loading through Plasmodesmata: A Biophysical Analysis.Plant physiology · 2017Article
- Article
- Diffusion or bulk flow: how plasmodesmata facilitate pre-phloem transport of assimilates.Journal of plant research · 2015Review
- Apoplastic and symplastic phloem loading in Quercus robur and Fraxinus excelsior.Journal of experimental botany · 2014Article
- SWEET17, a facilitative transporter, mediates fructose transport across the tonoplast of Arabidopsis roots and leaves.Plant physiology · 2014Article
- Evolutionary aspects of non-cell-autonomous regulation in vascular plants: structural background and models to study.Frontiers in plant science · 2014Article
- Article
- How phloem-feeding insects face the challenge of phloem-located defenses.Frontiers in plant science · 2013Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
8 authors at 2 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
To determine the driving forces for symplastic sugar flux between mesophyll and phloem, gradients of sugar concentrations and osmotic pressure were studied in leaf tissues of two Scrophulariaceae species, Alonsoa meridionalis and Asarina barclaiana. A. meridionalis has a typical symplastic configuration of minor-vein phloem, i.e. intermediary companion cells with highly developed plasmodesmal connections to bundle-sheath cells. In A. barclaiana, two types of companion cells, modified intermediary cells and transfer cells, were found in minor-vein phloem, giving this species the potential to have a complex phloem-loading mode. We identified all phloem-transported carbohydrates in both species and analyzed the levels of carbohydrates in chloroplasts, vacuoles, and cytoplasm of mesophyll cells by nonaqueous fractionation. Osmotic pressure was measured in single epidermal and mesophyll cells and in whole leaves and compared with calculated values for phloem sap. In A. meridionalis, a 2-fold concentration gradient for sucrose between mesophyll and phloem was found. In A. barclaiana, the major transported carbohydrates, sucrose and antirrhinoside, were present in the phloem in 22- and 6-fold higher concentrations, respectively, than in the cytoplasm of mesophyll cells. The data show that diffusion of sugars along their concentration gradients is unlikely to be the major mechanism for symplastic phloem loading if this were to occur in these species. We conclude that in both A. meridionalis and A. barclaiana, apoplastic phloem loading is an indispensable mechanism and that symplastic entrance of solutes into the phloem may occur by mass flow. The conditions favoring symplastic mass flow into the phloem are discussed.
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