Sieve elements general term sieve tube elements

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Unformatted text preview: Sieve elements in general term. • Sieve elements (general term) – Sieve-tube elements (angiosperms), sieve cells (gymnosperms) • Sieve plate • Pores essentially open channels allowing bulk flow between cells • Membrane must stay intact and pores must remain open – No nucleus or tonoplast when mature Translocation these are the cells that are make the Phloem From: Front Plant Sci. 2012; 3: 151. Published online 2012 July 13. Prepublished online 2012 April 18. doi: 10.3389/fpls.2012.00151 Translocation © 2012 Jensen, Mullendore, Holbrook, Bohr, Knoblauch and Bruus. Structural Aspects • Companion cells every one these cells have companion cells every phloem sieve tube has a companion cells – Many plasmodesmata connections with sieve tube members – Take over some control of sieve tube member metabolic functions – Source of ATP Translocation Structural Aspects • P-protein (slime) sieve tube cell – Functions in sealing off damaged sieve elements, plugging pores – Rapid and temporary Translocation • Callose Structural Aspects – Beta-(1-3) glucan – Synthesized by protein in plasma membrane – Synthesized in response to damage or other stress – Long term sealing of Aniline Blue damage http://www.uni-graz.at/~huber/ http://pix.botany.org/ Translocation http://www.biologie.uni-hamburg.de Translocation Characteristics • Translocated substances...
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