scholarly journals Interaction between Long-Distance Transport Factor and Hsp70-Related Movement Protein of Beet Yellows Virus

2002 ◽  
Vol 76 (21) ◽  
pp. 11003-11011 ◽  
Author(s):  
Alexey I. Prokhnevsky ◽  
Valera V. Peremyslov ◽  
Alberto J. Napuli ◽  
Valerian V. Dolja
Keyword(s):  
Movement Protein ◽  
Vascular System ◽  
Cell Movement ◽  
In Planta ◽  
Long Distance ◽  
Long Distance Transport ◽  
Transport Factor ◽  
Systemic Spread ◽  
Beet Yellows Virus ◽  
Distance Transport

ABSTRACT Systemic spread of viruses in plants involves local movement from cell to cell and long-distance transport through the vascular system. The cell-to-cell movement of the Beet yellows virus (BYV) is mediated by a movement protein that is an Hsp70 homolog (Hsp70h). This protein is required for the assembly of movement-competent virions that incorporate Hsp70h. By using the yeast two-hybrid system, in vitro coimmunoprecipitation, and in planta coexpression approaches, we show here that the Hsp70h interacts with a 20-kDa BYV protein (p20). We further demonstrate that p20 is associated with the virions presumably via binding to Hsp70h. Genetic and immunochemical analyses indicate that p20 is dispensable for assembly and cell-to-cell movement of BYV but is required for the long-distance transport of virus through the phloem. These results reveal a novel activity for the Hsp70h that provides a molecular link between the local and systemic spread of a plant virus by docking a long-distance transport factor to virions.

scholarly journals Leader Proteinase of Beet Yellows Virus Functions in Long-Distance Transport

2003 ◽  
Vol 77 (5) ◽  
pp. 2843-2849 ◽  
Author(s):  
Chih-Wen Peng ◽  
Alberto J. Napuli ◽  
Valerian V. Dolja
Keyword(s):  
Cell Movement ◽  
Protein Molecule ◽  
Virus Transport ◽  
Rna Amplification ◽  
Alanine Scanning Mutagenesis ◽  
Long Distance ◽  
Terminal Domain ◽  
Long Distance Transport ◽  
Beet Yellows Virus ◽  
Distance Transport

ABSTRACT The 66-kDa leader proteinase (L-Pro) of the Beet yellows virus (BYV) possesses a nonconserved N-terminal domain and a conserved, papain-like C-terminal domain. Previous work revealed that the N-terminal domain functions in RNA amplification, whereas the C-terminal domain is required for autoproteolysis. Alanine-scanning mutagenesis was applied to complete the functional analysis of L-Pro throughout the virus life cycle. This analysis indicated that the C-terminal domain of L-Pro, in addition to being required for proteolysis, also functions in RNA amplification and that these two functions are genetically separable. Examination of the role of L-Pro in BYV cell-to-cell movement revealed that none of the 20 examined replication-competent mutants was movement defective. In contrast, six of the L-Pro mutations affected the long-distance transport of BYV to various degrees, whereas three mutations completely abolished the transport. Because these mutations were located throughout the protein molecule, both domains of L-Pro function in virus transport. We conclude that in addition to previously identified functions of L-Pro, it also serves as the BYV long-distance transport factor.

scholarly journals ABC transporter OsABCG18 controls the shootward transport of cytokinins and grain yield in rice

2019 ◽  
Vol 70 (21) ◽  
pp. 6277-6291 ◽  
Author(s):  
Jiangzhe Zhao ◽  
Ningning Yu ◽  
Min Ju ◽  
Biao Fan ◽  
Yanjun Zhang ◽  
...  
Keyword(s):  
Grain Yield ◽  
Oryza Sativa L ◽  
Xylem Sap ◽  
In Planta ◽  
Long Distance ◽  
Efflux Transport ◽  
Long Distance Transport ◽  
Atp Binding Cassette Transporter ◽  
Novel Strategy ◽  
Distance Transport

Abstract Cytokinins are one of the most important phytohormones and play essential roles in multiple life processes in planta. Root-derived cytokinins are transported to the shoots via long-distance transport. The mechanisms of long-distance transport of root-derived cytokinins remain to be demonstrated. In this study, we report that OsABCG18, a half-size ATP-binding cassette transporter from rice (Oryza sativa L.), is essential for the long-distance transport of root-derived cytokinins. OsABCG18 encodes a plasma membrane protein and is primarily expressed in the vascular tissues of the root, stem, and leaf midribs. Cytokinin profiling, as well as [14C]trans-zeatin tracer, and xylem sap assays, demonstrated that the shootward transport of root-derived cytokinins was significantly suppressed in the osabcg18 mutants. Transport assays in tobacco (Nicotiana benthamiana) indicated that OsABCG18 exhibited efflux transport activities for various substrates of cytokinins. While the mutation reduced root-derived cytokinins in the shoot and grain yield, overexpression of OsABCG18 significantly increased cytokinins in the shoot and improved grain yield. The findings for OsABCG18 as a transporter for long-distance transport of cytokinin provide new insights into the cytokinin transport mechanism and a novel strategy to increase cytokinins in the shoot and promote grain yield.

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

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