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United States Department of Agriculture

Agricultural Research Service

Title: Carbohydrate Export from the Leaf - A Highly Regulated Process and Target to Enhance Photosynthesis and Productivity

item Ainsworth, Elizabeth - Lisa
item Bush, D

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2010
Publication Date: 11/4/2011
Citation: Ainsworth, E.A., Bush, D.R. 2011. Carbohydrate export from the leaf - a highly regulated process and target to enhance photosynthesis and productivity. Plant Physiology. 155(1):64-69.

Interpretive Summary: Growth and development in multicellular plants is a globally integrated process in which primary assimilation in source tissues is balanced by the metabolic needs of heterotrophic sinks. The complex coordination of source and sink activity between highly dispersed organs is mediated by dynamic regulatory processes in the plant's vascular system. The regulatory system that controls phloem loading is likely to be only one of several systems that balance carbon assimilation with utilization. Indeed, recent demonstration of several complex signaling and control processes linked through the phloem, suggests many pathways involved with global regulation of plant growth have yet to be discovered. In a future world of elevated [CO2], enhancing the capacity for sucrose export and carbon utilization is an important component of maximizing photosynthesis and yield.

Technical Abstract: The phloem is a central component of the plant's complex vascular system that plays a vital role in moving photoassimilates from sites of primary acquisition to the heterotrophic tissues and organs of the plant. Indeed, as much as 50-80% of the CO2 photoassimilated in a mature leaf is transported out of the leaf in the phloem to satisfy the needs of the non-photosynthetic organs of the plant. In recent years, new data has shown that the phloem also plays a key role in moving information molecules that coordinate many facets of plant growth and development. This update will focus on phloem loading's contribution to assimilate partitioning, and its role in balancing photosynthetic activity with sink utilization of photoassimilates.

Last Modified: 10/17/2017
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