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. 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

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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.
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References

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