Journal ArticleDOI
Osmoregulation and the control of phloem-sap composition in Ricinus communis L.
J. A. C. Smith,J. A. Milburn +1 more
Reads0
Chats0
TLDR
The increase in K+ levels in the phloem in darkness is interpreted as an osmoregulatory response to conditions of restricted solute availability, and can be explained on the basis of the sucrose-H+ co-transport mechanism ofphloem loading.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 Ca2+ 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.read more
Citations
More filters
Journal ArticleDOI
The phloem, a miracle of ingenuity
TL;DR: This review deals with aspects of the cellular and molecular biology of the sieve element/companion cell complex, the functional unit of sieve tubes in angiosperms.
Journal ArticleDOI
The plant vascular system: evolution, development and functions
William J. Lucas,Andrew Groover,Raffael Lichtenberger,Kaori Miyashima Furuta,Shri Ram Yadav,Ykä Helariutta,Xin Qiang He,Hiroo Fukuda,Julie Kang,Siobhan M. Brady,John W. Patrick,John S. Sperry,Akiko Yoshida,Ana Flor López-Millán,Michael A. Grusak,Pradeep Kachroo +15 more
TL;DR: The evolutionary events that gave rise to the tracheophytes are examined, followed by analysis of the genetic and hormonal networks that cooperate to orchestrate vascular development in the gymnosperms and angiosperms, in a comprehensive picture of the state-of-the-art in the area of plant vascular biology.
Journal ArticleDOI
PHLOEM UNLOADING: Sieve Element Unloading and Post-Sieve Element Transport.
TL;DR: The transport events from the sieve elements to the sites of utilization within the recipient sink cells contribute tophloem unloading, which links sink metabolism and/or compartmentation with phloem transport to, and partitioning between, sinks.
Journal ArticleDOI
The biochemical and molecular basis for photosynthetic acclimation to elevated atmospheric CO2
TL;DR: A model for the control of Rubisco protein accumulation is presented that emphasizes the role of subunit message translation as well as the abundance of sub unit messages as components of the acclimation response.
References
More filters
Book
CRC Handbook of Chemistry and Physics
TL;DR: CRC handbook of chemistry and physics, CRC Handbook of Chemistry and Physics, CRC handbook as discussed by the authors, CRC Handbook for Chemistry and Physiology, CRC Handbook for Physics,
Journal ArticleDOI
A modified single solution method for the determination of phosphate in natural waters
J. Murphy,J.P. Riley +1 more
TL;DR: In this article, a single solution reagent was described for the determination of phosphorus in sea water, which consists of an acidified solution of ammonium molybdate containing ascorbic acid and a small amount of antimony.
Journal ArticleDOI
Determination of nitrate in sea water by cadmium-copper reduction to nitrite
TL;DR: An accurate, dependable determination of 0−60 μg-at/l. of NO−3-N in sea water has been developed by as mentioned in this paper, where the sample is treated with tetrasodium ethylenediaminetetraacetate solution and passed through a column of copperized cadmium filings.
Journal ArticleDOI
Hydrostatic pressure and osmotic potential in leaves of mangroves and some other plants.
TL;DR: A replicative form isolated by Kaerner and Hoffmann-Berling from E. coli infected with the RNA phage fr shows the same melting profile, Tm, RNAase resistance, and buoyant density in CS2SO4 as the Replicative form of MS2.