Cell Biology

Electronic Journal of Biotechnology ISSN: 0717-3458 Vol. 9 No. 3, Issue of April 15, 2006
© 2006 by Pontificia Universidad Católica de Valparaíso -- Chile  
DOI: 10.2225/vol9-issue3-fulltext-21  

Sunflower storage proteins are transported in dense vesicles that contain proteins homologous to the pumpkin vacuolar sorting receptor PV 72

María Isabel Molina
Department of Plant Biology
Michigan State University
East Lansing, MI 48824-1312 USA
Tel: 517 353 9399
Fax: 517 353 1926
E-mail: molinam3@msu.edu

 Marisa Otegui
Department of Botany
University of Wisconsin
224 Birge Hall- 430, Lincoln Drive
WI 53706-. USA
Tel: 608 265 5703
Fax: 608263 7509
E-mail: otegui@wisc.edu

 Silvana Petruccelli*
Centro de Investigación y Desarrollo en Criotecnología de Alimentos
Facultad de Ciencias Exactas
Universidad Nacional de La Plata
Calle 47 y 116 (1900)
La Plata, Argentina
Tel/Fax: 54 221 4249287/4254853
E-mail: silvana@biol.unlp.edu.ar

*Corresponding author

Financial support: ANPCyT (Agencia de Promoción Científica y Tecnológica)-ASAGIR (PICTO-13156). SP is member of the research career of CONICET (Argentina).

Keywords: developing sunflower seeds, storage proteins, transport pathway, vacuolar sorting, vacuolar sorting receptor.


BiP: chaperone of the heat shock protein family HSP70
CCV: clathrin-coated vesicle
DV: dense vesicles
ER: endoplasmic reticulum
M: microsomes
MVB: mutivesicular bodies
NPIRL: asparagine-proline-isoleucine-arginine-leucine
PAC: precursor accumulating vesicles
PSV: protein storage vacuoles
PV: percoll vesicles
R5.5: development stage of sunflower head, I2 and I3 immature sunflower embryos in different stages of develop
TIP: tonoplast intrinsic protein
VSR: vacuolar sorting receptor
BP-80: pea VSR

Abstract   Reprint (PDF)

Storage proteins are transported to a special storage compartments in seeds by Golgi dependent or independent pathways depending on the plant species. The aim of this work was to study the sunflower storage protein transport pathway and identified component of the sorting machinery. Immature sunflower seeds were analyzed by subcellular fractionation (using percoll and sucrose gradients) and electron microscopy. The vesicles isolated with percoll, have precursors of 11S globulins, α-TIP, δ-TIP, BiP, and two proteins that have homology to the pumpkin vacuolar sorting receptor PV72. Sucrose isolated vesicles have the same composition than percoll ones, except for the lack of BiP and the presence of only one protein that has reactivity with pea VSR BP80. Electronic micrographies of developing seeds show that the formation of electron dense aggregates starts in the endoplasmic reticulum, and that these aggregates are very abundant in the trans-Golgi apparatus, where release of dense vesicles happens. These vesicles contain a homolog of PV72 in their membranes. Storage proteins are also detected in multivesicular bodies whose membranes have reactivity with PV72 serum. All these results indicated that sunflower storage proteins are transported to protein storage vacuoles by a Golgi dependent pathway in a process in which homologous of PV72 are involved.

Supported by UNESCO / MIRCEN network 
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