Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2011 Jan;155(1):64-9.
doi: 10.1104/pp.110.167684. Epub 2010 Oct 22.

Carbohydrate export from the leaf: a highly regulated process and target to enhance photosynthesis and productivity

Elizabeth A Ainsworth  1 , Daniel R Bush
Affiliations

Carbohydrate export from the leaf: a highly regulated process and target to enhance photosynthesis and productivity

Elizabeth A Ainsworth et al. Plant Physiol. 2011 Jan.
No abstract available

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Phloem loading capacity is a function of Suc symporter abundance in the plasma membrane, which is directly proportional to the rate of symporter transcription. The transcription rate of the symporter in the phloem is regulated by a signaling cascade that is controlled by changes in Suc levels. Suc levels are a dynamic balance between loading activity and export, and rapid turnover of both symporter mRNA and protein allows for dynamic control. If sink demand is high, Suc levels are low and transcription is high. If sink demand drops, export slows and Suc builds up and down-regulates symporter transcription and abundance. As phloem-loading capacity drops, carbohydrate then builds up in the mesophyll and photosynthesis is down-regulated.
See this image and copyright information in PMC

References

    1. Adams WW, III, Watson AM, Mueh KE, Amiard V, Turgeon R, Ebbert V, Logan BA, Combs AF, Demmig-Adams B. (2007) Photosynthetic acclimation in the context of structural constraints to carbon export from leaves. Photosynth Res 94: 455–466 - PubMed
    1. Ainsworth EA, Long SP. (2005) What have we learned from 15 years of free-air CO2 enrichment (FACE)? A meta-analytic review of the responses of photosynthesis, canopy properties and plant production to rising CO2. New Phytol 165: 351–371 - PubMed
    1. Ainsworth EA, Rogers A, Nelson R, Long SP. (2004) Testing the “source-sink” hypothesis of down-regulation of photosynthesis in elevated [CO2] in the field with single gene substitutions in Glycine max. Agric For Meteorol 122: 85–94
    1. Amiard V, Mueh KE, Demmig-Adams B, Ebbert V, Turgeon R, Adams WW., III (2005) Anatomical and photosynthetic acclimation to the light environment in species with differing mechanisms of phloem loading. Proc Natl Acad Sci USA 102: 12968–12973 - PMC - PubMed
    1. Arp WJ. (1991) Effects of source-sink relations on photosynthetic acclimation to elevated CO2. Plant Cell Environ 14: 869–875

LinkOut - more resources