37397
2014
2014
eng
11
11
9
article
PLoS
San Fransisco
1
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Reduction of the cytosolic phosphoglucomutase in arabidopsis reveals impact on plant growth, seed and root development, and carbohydrate partitioning
Phosphoglucomutase (PGM) catalyses the interconversion of glucose 1-phosphate (G1P) and glucose 6-phosphate (G6P) and exists as plastidial (pPGM) and cytosolic (cPGM) isoforms. The plastidial isoform is essential for transitory starch synthesis in chloroplasts of leaves, whereas the cytosolic counterpart is essential for glucose phosphate partitioning and, therefore, for syntheses of sucrose and cell wall components. In Arabidopsis two cytosolic isoforms (PGM2 and PGM3) exist. Both PGM2 and PGM3 are redundant in function as single mutants reveal only small or no alterations compared to wild type with respect to plant primary metabolism. So far, there are no reports of Arabidopsis plants lacking the entire cPGM or total PGM activity, respectively. Therefore, amiRNA transgenic plants were generated and used for analyses of various parameters such as growth, development, and starch metabolism. The lack of the entire cPGM activity resulted in a strongly reduced growth revealed by decreased rosette fresh weight, shorter roots, and reduced seed production compared to wild type. By contrast content of starch, sucrose, maltose and cell wall components were significantly increased. The lack of both cPGM and pPGM activities in Arabidopsis resulted in dwarf growth, prematurely die off, and inability to develop a functional inflorescence. The combined results are discussed in comparison to potato, the only described mutant with lack of total PGM activity.
PLoS one
10.1371/journal.pone.0112468
25401493
1932-6203
wos:2014
e112468
WOS:000345158700047
Fettke, J (reprint author), Univ Potsdam, Potsdam, Germany., fettke@uni-potsdam.de
Deutsche Forschungsgemeinschaft [DFG-Az. FE 1030/1-1, FE 1030/2-1];
Human Frontier Science Program Long-Term fellowship; Alexander von
Humboldt Feodor Lynen fellowship
Irina Malinova
Hans-Henning Kunz
Saleh Alseekh
Karoline Herbst
Alisdair R. Fernie
Markus Gierth
Jörg Fettke
Institut für Biochemie und Biologie
Referiert
Open Access
35937
2012
2012
eng
3011
3029
19
8
63
article
Oxford Univ. Press
Oxford
1
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Two carbon fluxes to reserve starch in potato (Solanum tuberosum L.) tuber cells are closely interconnected but differently modulated by temperature
Parenchyma cells from tubers of Solanum tuberosum L. convert several externally supplied sugars to starch but the rates vary largely. Conversion of glucose 1-phosphate to starch is exceptionally efficient. In this communication, tuber slices were incubated with either of four solutions containing equimolar [U-C-14]glucose 1-phosphate, [U-C-14]sucrose, [U-C-14]glucose 1-phosphate plus unlabelled equimolar sucrose or [U-C-14]sucrose plus unlabelled equimolar glucose 1-phosphate. C-14-incorporation into starch was monitored. In slices from freshly harvested tubers each unlabelled compound strongly enhanced C-14 incorporation into starch indicating closely interacting paths of starch biosynthesis. However, enhancement disappeared when the tubers were stored. The two paths (and, consequently, the mutual enhancement effect) differ in temperature dependence. At lower temperatures, the glucose 1-phosphate-dependent path is functional, reaching maximal activity at approximately 20 degrees C but the flux of the sucrose-dependent route strongly increases above 20 degrees C. Results are confirmed by in vitro experiments using [U-C-14]glucose 1-phosphate or adenosine-[U-C-14]glucose and by quantitative zymograms of starch synthase or phosphorylase activity. In mutants almost completely lacking the plastidial phosphorylase isozyme(s), the glucose 1-phosphate-dependent path is largely impeded. Irrespective of the size of the granules, glucose 1-phosphate-dependent incorporation per granule surface area is essentially equal. Furthermore, within the granules no preference of distinct glucosyl acceptor sites was detectable. Thus, the path is integrated into the entire granule biosynthesis. In vitro C-14-incorporation into starch granules mediated by the recombinant plastidial phosphorylase isozyme clearly differed from the in situ results. Taken together, the data clearly demonstrate that two closely but flexibly interacting general paths of starch biosynthesis are functional in potato tuber cells.
Journal of experimental botany
10.1093/jxb/ers014
0022-0957
wos:2011-2013
WOS:000304196900014
Fettke, J (reprint author), Univ Potsdam, Inst Biochem & Biol, Dept Plant Physiol, D-14476 Potsdam, Germany., fettke@uni-potsdam.de
Deutsche Forschungsgemeinschaft (DFG) [Sonderforschungsbereich 429, FE
1030/1-1]
Jörg Fettke
Lydia Leifels
Henrike Brust
Karoline Herbst
Martin Steup
eng
uncontrolled
glucose 1-phosphate
eng
uncontrolled
phosphorylase
eng
uncontrolled
potato tubers
eng
uncontrolled
starch
eng
uncontrolled
starch synthase
Institut für Biochemie und Biologie
Referiert