The promoter of the Arabidopsis thaliana SUC2 sucrose-H+ symporter gene directs expression of ?-glucuronidase to the phloem: Evidence for phloem loading and unloading by SUC2

Planta ◽  
1995 ◽  
Vol 196 (3) ◽  
Author(s):  
Elisabeth Truernit ◽  
Norbert Sauer
Keyword(s):  
Arabidopsis Thaliana ◽  
Phloem Loading ◽  
Loading And Unloading ◽  
Phloem Loading And Unloading

scholarly journals Phloem loading and unloading of Cowpea mosaic virus in Vigna unguiculata

2002 ◽  
Vol 83 (6) ◽  
pp. 1493-1504 ◽  
Author(s):  
M. S. Silva ◽  
J. Wellink ◽  
R. W. Goldbach ◽  
J. W. M. van Lent
Keyword(s):  
Mosaic Virus ◽  
Vigna Unguiculata ◽  
Cell Movement ◽  
Cell Types ◽  
Phloem Loading ◽  
Cowpea Mosaic Virus ◽  
Class Iii ◽  
Long Distance ◽  
Loading And Unloading ◽  
Phloem Loading And Unloading

Within their host plants, viruses spread from the initially infected cell through plasmodesmata to neighbouring cells (cell-to-cell movement), until reaching the phloem for rapid invasion of the younger plant parts (long-distance or vascular movement). Cowpea mosaic virus (CPMV) moves from cell-to-cell as mature virions via tubules constructed of the viral movement protein (MP). The mechanism of vascular movement, however, is not well understood. The characteristics of vascular movement of CPMV in Vigna unguiculata (cowpea) were examined using GFP-expressing recombinant viruses. It was established that CPMV was loaded into both major and minor veins of the inoculated primary leaf, but was unloaded exclusively from major veins, preferably class III, in cowpea trifoliate leaves. Phloem loading and unloading of CPMV was scrutinized at the cellular level in sections of loading and unloading veins. At both loading and unloading sites it was shown that the virus established infection in all vascular cell types with the exception of companion cells (CC) and sieve elements (SE). Furthermore tubular structures, indicative of virion movement, were never found in plasmodesmata connecting phloem parenchyma cells and CC or CC and SE. In cowpea, SE are symplasmically connected only to the CC and these results therefore suggest that CPMV employs a mechanism for phloem loading and unloading that is different from the typical tubule-guided cell-to-cell movement in other cell types.

scholarly journals Phloem loading and unloading of sugars and amino acids

2003 ◽  
Vol 26 (1) ◽  
pp. 37-56 ◽  
Author(s):  
S. LALONDE ◽  
M. TEGEDER ◽  
M. THRONE-HOLST ◽  
W. B. FROMMER ◽  
J. W. PATRICK
Keyword(s):  
Amino Acids ◽  
Phloem Loading ◽  
Loading And Unloading ◽  
Phloem Loading And Unloading
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