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Titolo:
Sucrose-starch conversion in heterotrophic tissues of plants
Autore:
Pozueta-Romero, J; Perata, P; Akazawa, T;
Indirizzi:
Univ Navarra, Inst Biotecnol Agraria Plantas, Navarra 31192, Spain Univ Navarra Navarra Spain 31192 l Agraria Plantas, Navarra 31192, Spain Univ Pisa, Sez Fisiol Vegetale, Dipartimento Biol Piante Agrarie, Pisa, Italy Univ Pisa Pisa Italy ale, Dipartimento Biol Piante Agrarie, Pisa, Italy Nagoya Univ, Sch Agr Sci, Nagoya, Aichi, Japan Nagoya Univ Nagoya Aichi Japan a Univ, Sch Agr Sci, Nagoya, Aichi, Japan Suzuka Int Univ, Suzuka, Mie 5100263, Japan Suzuka Int Univ Suzuka Mie Japan 5100263 Univ, Suzuka, Mie 5100263, Japan
Titolo Testata:
CRITICAL REVIEWS IN PLANT SCIENCES
fascicolo: 4, volume: 18, anno: 1999,
pagine: 489 - 525
SICI:
0735-2689(1999)18:4<489:SCIHTO>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
ADP-GLUCOSE PYROPHOSPHORYLASE; POTATO SOLANUM-TUBEROSUM; ARABIDOPSIS-THALIANA L; DEVELOPING PEA EMBRYOS; SYCAMORE ACER-PSEUDOPLATANUS; CAULIFLOWER-BUD AMYLOPLASTS; INNER-ENVELOPE MEMBRANES; ZEA-MAYS L; ADENOSINE 5'-DIPHOSPHOGLUCOSE PYROPHOSPHORYLASE; INCREASED ADPGLUCOSE PYROPHOSPHORYLASE;
Keywords:
adenylate translocator; ADPGlc; ADPGlc pyrophosphorylase; amyloplast; cyclic turnover of starch; phosphate translocator; source-sink; starch biosynthesis; sucrose-starch transition; sucrose synthase; transgenic plants; UDPGlc pyrophosphorylase;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
216
Recensione:
Indirizzi per estratti:
Indirizzo: Pozueta-Romero, J Univ Navarra, Inst Biotecnol Agraria Plantas, Ctra Multilva S-N, Navarra 31192, Spain Univ Navarra Ctra Multilva S-N Navarra Spain31192 pain
Citazione:
J. Pozueta-Romero et al., "Sucrose-starch conversion in heterotrophic tissues of plants", CR R PLANT, 18(4), 1999, pp. 489-525

Abstract

The historical progress in recent years pertaining to the sucrose-starch conversion in heterotrophic tissues of plants has been described. Special attention has been focused on the enzymatic breakdown of sucrose to produce hexose units that are transported to the amyloplast compartment by means of specific translocator molecules and act as glucose donors for starch biosynthesis. Although the current prevailing view is that variable mechanisms operate in different plant tissues and organs, it is often argued that the following enzymic steps are essential in the overall step of sucrose to starch conversion:sucrose + UDP --> UDPGlc + Fru (sucrose synthase-SS)UDPGlc + PPi --> GlP + UTP (UDPGlc pyrophosphorylase-UGPase)GlP + ATP --> ADPGlc + PPi (ADPGlc pyrophosphorylase-AGPase)ADPGlc --> starch (starch synthase)The presence of an ADPGlc-specific translocator in the amyloplast envelopehas been demonstrated in a number of plant sources, which indicates the potential role of ADPGlc-synthesizing machineries located in the cytosol of starch-storing cells. Although it was initially believed that AGPase is present exclusively in the amyloplast compartment, the presence of a cytosolic enzyme has been shown in some cereals. The SS has a potential to produce ADPGlc, but the general belief is that this is not a dominant reaction in themechanism of starch biosynthesis. Numerous experimental trials have been reported by many scientists employing transgenic plants transformed with cDNAs either in antisense- or sense- orientation encoding enzymes which are presumably involved in the process of sucrose-starch conversion. Although great caution is needed to interpret the data obtained, the general picture iscontradictory to the mechanism presented above. It now appears that serious reconsideration is needed for the possible mechanism of SS-catalyzed ADPGlc formation and its subsequent link to starch formation. In the newly proposed mechanistic scheme, which appears to be consistent with the results byother scientists as well, hexokinase, phosphoglucomutase (PGM), and ADPGlcformation by AGPase are components in the cyclic turnover of starch molecules in the amyloplast compartment.

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Documento generato il 04/04/20 alle ore 21:49:39