title: The role of lateral roots in bypass flow in rice (Oryza sativa L.).
abstract: Although an apoplastic pathway (the so-called bypass flow) is implicated in the uptake of Na(+) by rice growing in saline conditions, the point of entry of this flow into roots remains to be elucidated. We investigated the role of lateral roots in bypass flow using the tracer trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS) and the rice cv. IR36. PTS was identified in the vascular tissue of lateral roots using both epifluorescence microscopy and confocal laser scanning microscopy. Cryo-scanning electron microscopy and epifluorescence microscopy of sections stained with berberine-aniline blue revealed that the exodermis is absent in the lateral roots. We conclude that PTS can move freely through the cortical layers of lateral roots, enter the stele and be transported to the shoot via the transpiration stream.
authors.affiliation: Department of Biology and Environmental Science, School of Life Sciences, University of Sussex, Brighton BN19QG, UK. B.Faiyue@sussex.ac.uk
authors.forename: Bualuang
authors.initials: B
authors.lastname: Faiyue
authors.forename: Mohammed J
authors.initials: MJ
authors.lastname: Al-Azzawi
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Flowers
mesh_terms: D001692:Biological Transport; D006813:Humidity; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D012275:Oryza / Q000033:anatomy & histology / Q000502:physiology*; D018517:Plant Roots / Q000033:anatomy & histology* / Q000502:physiology*; D018520:Plant Shoots / Q000737:chemistry; D018526:Plant Transpiration; D011092:Polyethylene Glycols / Q000494:pharmacology; D011721:Pyrenes / Q000378:metabolism; D012825:Silicon / Q000494:pharmacology; D013451:Sulfonic Acids / Q000378:metabolism
chemical_list: C538892:8-hydroxy-1,3,6-pyrenetrisulfonic acid; D011721:Pyrenes; D013451:Sulfonic Acids; D011092:Polyethylene Glycols; D012825:Silicon