Oxygen isotope composition of phloem sap in relation to leaf water in Ricinus communis

Functional Plant Biology : FPB
Lucas A CernusakGraham D Farquhar

Abstract

We measured the oxygen isotope composition of both the water and dry matter components of phloem sap exported from photosynthesising Ricinus communis L. leaves. The 18O / 16O composition of exported dry matter matched almost exactly that expected for equilibrium with average lamina leaf water (leaf water exclusive of water associated with primary veins) with an isotope effect of αo=1.027, where αo=Ro / Rw , and Ro and Rw are 18O / 16O of organic molecules and water, respectively. Average lamina leaf water was enriched by 14-22‰ compared with source water under our experimental conditions, and depleted by 4-7‰, compared with evaporative site water. This showed that it is the average lamina leaf water 18O / 16O signal that is exported from photosynthesising leaves rather than a signal more closely related to that of evaporative site water or source water. Additionally, we found that water exported in phloem sap from photosynthesising leaves was enriched compared with source water; the mean phloem water enrichment observed for leaf petioles was 4.0 ± 1.5‰ (mean ± 1 s.d., n = 27). Phloem water collected from stem bases was also enriched compared with source water. However, the enrichment was approximately 0.8 times that observed fo...Continue Reading

Citations

Jun 9, 2020·Rapid Communications in Mass Spectrometry : RCM·Marco M LehmannAnsgar Kahmen
May 11, 2011·Plant, Cell & Environment·Nerea Ubierna, John D Marshall
May 1, 2005·Functional Plant Biology : FPB·Graham D Farquhar, Lucas A Cernusak
Apr 25, 2017·Plant, Cell & Environment·Marco M LehmannMatthias Saurer
Oct 16, 2016·Plant, Cell & Environment·M M BarbourT N Buckley
Mar 1, 2007·Functional Plant Biology : FPB·Margaret M Barbour
Apr 5, 2007·Plant, Cell & Environment·Romain L BarnardNina Buchmann
Feb 28, 2007·Plant, Cell & Environment·Margaret M BarbourNate G McDowell
Nov 6, 2009·Planta·Britta HartardMichael Lakatos
Dec 7, 2007·Journal of Experimental Botany·Lucas A CernusakJohn D Marshall
May 23, 2015·Plant, Cell & Environment·Xin SongMargaret M Barbour
Dec 31, 2015·Plant, Cell & Environment·Lucas A CernusakGraham D Farquhar
Mar 13, 2014·Plant, Cell & Environment·Xin SongMargaret M Barbour
Jul 9, 2016·Plant, Cell & Environment·Meisha Holloway-PhillipsGraham D Farquhar
Jan 1, 2006·Functional Plant Biology : FPB·Margaret M BarbourGraham D Farquhar
Oct 7, 2005·Journal of Experimental Botany·Bhaskar R BondadaKenneth A Shackel
Dec 10, 2013·Isotopes in Environmental and Health Studies·Michael ZechDieter Juchelka
Jan 11, 2007·Plant Physiology·Graham D FarquharBelinda Barnes
Aug 29, 2021·Scientific Reports·Florian CueniAnsgar Kahmen

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