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PREMIER CAT - Resolving the ultrastructure of sink sieve elements in plasmodesmata of Arabidopsis and Populus root tips


EMSL Project ID
48513

Abstract

The phloem of higher plants functions as a conduit, distributing photosynthetically derived constituents (mainly sucrose) from sites of synthesis (sources; i.e. leaves) to heterotrophic tissues where they are used for cell growth and maintenance (sinks; i.e. roots). This tube system is composed of specialized living cells, called sieve elements, that have undergone partial autolysis of some organelles yielding a relatively free lumen to accommodate low-resistance flow of assimilates. Sieve elements are stacked end-on-end and are connected by pore-perforated cell walls, called sieve plates (Mullendore et al., 2010). Flow of assimilates from source to sink is postulated to be a result of a passive osmotically generated pressure differential (Münch, 1930). Meaning, assimilates are loaded into source sieve elements which results in an increase of hydrostatic pressure and unloading from sink sieve elements leads to a decrease of hydrostatic pressure which creates a pressure differential driving passive flow of assimilates from source to sink. Unloading of assimilates into sink tissues provides humans with most of our food energy requirements but is the least understood area in phloem physiology.

Project Details

Start Date
2014-05-15
End Date
2014-09-30
Status
Closed

Team

Principal Investigator

Michael Knoblauch
Institution
Washington State University

Team Members

Timothy Ross-Elliott
Institution
Washington State University

Daniel Mullendore
Institution
Washington State University