Baroja-Fernandez, Edurne , Munoz, Francisco Jose , Etxeberria, Ed , González, Pedro , Ezquer, Ignacio , Pozueta-Romero, Javier .
Endocytic uptake and traffic of sucrose linked to both starch and cellulose biosynthesis are processes specifically triggered by sucrose that require the synthesis de novo of proteins.
We have recently established that an important pool of sucrose linked to starch biosynthesis in heterotrophic cells is taken up by endocytosis (Etxeberria et al. 2005 Plant Cell Physiol. 46, 474-481; Baroja-Fernandez et al. 2006 Plant Cell Physiol. 47, 447-456). Whether this mechanism is also involved in the sucrose-cellulose conversion process was investigated by comparing the rates of cellulose accumulation in sycamore cells cultured in the presence or absence of the endocytic inhibitors wortmannin-A, 2-4(4-morpholynyl-)8-phenyl-4H-1 benzopyran-4-1 (LY294002) and latrunculin B. These analyses revealed that sucrose-cellulose conversion involves two phases, the second of which being 35% sensitive to the effect of endocytic inhibitors. Whether endocytic uptake, traffic and metabolism of sucrose requires the de novo synthesis of proteins was investigated by comparing the rates of accumulation of the endocytic marker lucifer yellow, sucrose and starch in sycamore cells in the presence or absence of the transcriptional inhibitor cordycepine and the translational elongation inhibitor cycloheximide. These analyses revealed that the two compounds exerted a strong inhibitory effect on the accumulation of lucifer yellow, sucrose and starch. The stimulatory effect of sucrose in the endocytic uptake of external solutes could not be replaced by the non-metabolizable sucrose analogues palatinose and turanose. The overall results (a) provide a first indication that the endocytic uptake of sucrose linked to both starch and cellulose biosynthesis requires de novo synthesis of proteins and (b) further strengthen that the endocytic uptake of external solutes is very specifically triggered by sucrose.
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1 - Instituto de Agrobiotecnologia, Universidad Publica de Navarra/CSIC, Ctra. Mutilva s/n, Mutilva Baja, Navarra, 31192, Spain
2 - Instituto de Agrobiotecnologia
3 - Citrus Research Center, Universuty of Florida
4 - Citrus Research Center, University of Florida
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM