scholarly journals Companion-Cell Specific Localization of Sucrose Synthase in Zones of Phloem Loading and Unloading

1993 ◽  
Vol 101 (3) ◽  
pp. 899-905 ◽  
Author(s):  
K. D. Nolte ◽  
K. E. Koch
Keyword(s):  
Sucrose Synthase ◽  
Phloem Loading ◽  
Companion Cell ◽  
Specific Localization ◽  
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

scholarly journals Amino Acid Transporters in Plants: Identification and Function

Plants ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 972
Author(s):  
Xuehui Yao ◽  
Jing Nie ◽  
Ruoxue Bai ◽  
Xiaolei Sui
Keyword(s):  
Amino Acid ◽  
Agricultural Production ◽  
Carbon Assimilation ◽  
Phloem Loading ◽  
Amino Acid Transporters ◽  
Molecular Identity ◽  
Current State ◽  
Loading And Unloading ◽  
Phloem Loading And Unloading ◽  
And Function

Amino acid transporters are the main mediators of nitrogen distribution throughout the plant body, and are essential for sustaining growth and development. In this review, we summarize the current state of knowledge on the identity and biological functions of amino acid transporters in plants, and discuss the regulation of amino acid transporters in response to environmental stimuli. We focus on transporter function in amino acid assimilation and phloem loading and unloading, as well as on the molecular identity of amino acid exporters. Moreover, we discuss the effects of amino acid transport on carbon assimilation, as well as their cross-regulation, which is at the heart of sustainable agricultural production.

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