Osmoregulation and the Control of Phloem-sap Composition in Ricinus Communis L

Overview

Journal Planta

Specialty Biology

Date 2013 Dec 7

PMID 24311262

Citations 19

Authors

J A Smith

J A Milburn

Affiliations

Soon will be listed here.

Abstract

Phloem-sap composition was studied in plants of Ricinus communis L. grown on a waterculture medium. The sap possessed a relatively high K(+):Na(+) ratio and low levels of Ca(2+) and free H(+). Sucrose and K(+) (together with its associated anions) accounted for 75% of the phloem-sap solute potential (Ψs). In plants kept in continuous darkness, a decrease in phloem-sap sucrose levels over 24h was accompanied by an increase in K(+) levels. Measurements of phloem-sap Ψs and xylem water potential (Ψ) indicated that this resulted in a partial maintenance of phloem turgor pressure Ψp. In darkness there was also a marked decrease in the malate content of the leaf tissue, and it is possible that organic carbon from this source was mobilized for export in the phloem. The results support the concept of the phloem sap as a symplastic phase. We interpret the increase in K(+) levels in the phloem in darkness as an osmoregulatory response to conditions of restricted solute availability. This reponse can be explained on the basis of the sucrose-H(+) co-transport mechanism of phloem loading.

Citing Articles

Sugar loading is not required for phloem sap flow in maize plants.

Babst B, Braun D, Karve A, Frank Baker R, Tran T, Kenny D Nat Plants. 2022; 8(2):171-180.

PMID: 35194203 DOI: 10.1038/s41477-022-01098-x.

Potassium in the Grape ( L.) Berry: Transport and Function.

Rogiers S, Coetzee Z, Walker R, Deloire A, Tyerman S Front Plant Sci. 2017; 8:1629.

PMID: 29021796 PMC: 5623721. DOI: 10.3389/fpls.2017.01629.

Comparative transcriptome combined with morpho-physiological analyses revealed key factors for differential cadmium accumulation in two contrasting sweet sorghum genotypes.

Feng J, Jia W, Lv S, Bao H, Miao F, Zhang X Plant Biotechnol J. 2017; 16(2):558-571.

PMID: 28703450 PMC: 5787832. DOI: 10.1111/pbi.12795.

Phloem turgor and the regulation of sucrose loading in Ricinus communis L.

Smith J, Milburn J Planta. 2013; 148(1):42-8.

PMID: 24311264 DOI: 10.1007/BF00385440.

Phloem transport, solute flux and the kinetics of sap exudation in Ricinus communis L.

Smith J, Milburn J Planta. 2013; 148(1):35-41.

PMID: 24311263 DOI: 10.1007/BF00385439.

References

van Bel A, van Erven A . A model for proton and potassium co-transport during the uptake of glutamine and sucrose by tomato internode disks. Planta. 2013; 145(1):77-82. DOI: 10.1007/BF00379930. View

Milburn J . An analysis of the response in phloem exudation on application of massage to Ricinus. Planta. 2014; 100(2):143-54. DOI: 10.1007/BF00385215. View

SCHOLANDER P, Hammel H, Hemmingsen E, Bradstreet E . HYDROSTATIC PRESSURE AND OSMOTIC POTENTIAL IN LEAVES OF MANGROVES AND SOME OTHER PLANTS. Proc Natl Acad Sci U S A. 1964; 52(1):119-25. PMC: 300583. DOI: 10.1073/pnas.52.1.119. View

Grange R, Peel A . Evidence for solution flow in the phloem of willow. Planta. 2014; 138(1):15-23. DOI: 10.1007/BF00392908. View

Hall S, Baker D, Milburn J . Phloem transport of (14)C-labelled assimilates in Ricinus. Planta. 2014; 100(3):200-7. DOI: 10.1007/BF00387036. View

Sharkey P, Pate J . Translocation from leaves to fruits of a legume, studied by a phloem bleeding technique: Diurnal changes and effects of continuous darkness. Planta. 2014; 128(1):63-72. DOI: 10.1007/BF00397180. View

Hutchings V . Sucrose and proton cotransport in Ricinus cotyledons : II. H(+) efflux and associated K(+) uptake. Planta. 2014; 138(3):237-41. DOI: 10.1007/BF00386817. View

Mitchell P . Translocations through natural membranes. Adv Enzymol Relat Areas Mol Biol. 1967; 29:33-87. DOI: 10.1002/9780470122747.ch2. View

Rees T, Beevers H . Pathways of Glucose Dissimilation in Carrot Slices. Plant Physiol. 1960; 35(6):830-8. PMC: 406047. DOI: 10.1104/pp.35.6.830. View

10.

Raven J . Regulation of solute transport at the cell level. Symp Soc Exp Biol. 1977; 31:73-99. View

11.

Mengel K, Haeder H . Effect of Potassium Supply on the Rate of Phloem Sap Exudation and the Composition of Phloem Sap of Ricinus communis. Plant Physiol. 1977; 59(2):282-4. PMC: 542382. DOI: 10.1104/pp.59.2.282. View

12.

Zimmermann U, Steudle E, Lelkes P . Turgor Pressure Regulation in Valonia utricularis: Effect of Cell Wall Elasticity and Auxin. Plant Physiol. 1976; 58(5):608-13. PMC: 542267. DOI: 10.1104/pp.58.5.608. View

13.

Kluge M . Regulation of carbon dioxide fixation in plants. Symp Soc Exp Biol. 1977; 31:155-75. View

14.

Hall S, Baker D . The chemical composition of Ricinus phloem exudate. Planta. 2014; 106(2):131-40. DOI: 10.1007/BF00383992. View