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Titolo:
Control of carbon partitioning and photosynthesis by the triose phosphate/phosphate translocator in transgenic tobacco plants (Nicotiana tabacum). II. Assessment of control coefficients of the triose phosphate/phosphate translocator
Autore:
Hausler, RE; Schlieben, NH; Flugge, UI;
Indirizzi:
Univ Cologne, Inst Bot, D-50931 Cologne, Germany Univ Cologne Cologne Germany D-50931 Inst Bot, D-50931 Cologne, Germany
Titolo Testata:
PLANTA
fascicolo: 3, volume: 210, anno: 2000,
pagine: 383 - 390
SICI:
0032-0935(200002)210:3<383:COCPAP>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
SUCROSE-PHOSPHATE SYNTHASE; ANTISENSE REPRESSION; METABOLIC SYSTEMS; ENZYME-ACTIVITIES; LINEAR TREATMENT; POTATO PLANTS; TRANSPORT; RESPONSES; EFFECTORS;
Keywords:
antisense repression/overexpression; carbon partitioning; control analysis; Nicotiana (transgenic); starch metabolism; triose phosphate/phosphate translocator;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
14
Recensione:
Indirizzi per estratti:
Indirizzo: Hausler, RE Univ Cologne, Inst Bot, Gyrhofstr 15, D-50931 Cologne, GermanyUniv Cologne Gyrhofstr 15 Cologne Germany D-50931 ne, Germany
Citazione:
R.E. Hausler et al., "Control of carbon partitioning and photosynthesis by the triose phosphate/phosphate translocator in transgenic tobacco plants (Nicotiana tabacum). II. Assessment of control coefficients of the triose phosphate/phosphate translocator", PLANTA, 210(3), 2000, pp. 383-390

Abstract

Transgenic tobacco (Nicotiana tabacum L.) plants with decreased and increased transport capacities of the chloroplast triose phosphate/phosphate translocator (TPT) were used to study the control the TPT exerts on the flux ofstarch and sucrose biosynthesis, as well as CO2 assimilation, respiration and photosynthetic electron transport. For this purpose, tobacco lines withan antisense repression of the endogenous TPT (alpha TPT) and tobacco lines overexpressing a TPT gene from Flaveria trinervia (FtTPT) were used. In ambient CO2, there was no or little effect of altered TPT transport activities on either rates of photosynthetic electron transport and/or CO2 assimilation. However, in elevated CO2 (1500 mu l.l(-1)) and low O-2 (2%) the TPT exerted strong control on the rate of CO2 assimilation (control coefficient for the wild type; C-TPT(JA) = 0.30) in saturating light. Similarly, the incorporation of C-14 into starch in high CO? was increased in tobacco plantswith decreased TPT activity, but was reduced in plants overexpressing the TPT from F, trinervia. Thus, the TPT exerted negative control on the rate of starch biosynthesis with a C-TPT(JStarch) = -0.19 in the wild type estimated from a hyperbolic curve fitted to the data points. This was less than the positive control strength on the rate of sucrose biosynthesis (C-TPT(JSuc), = 0.35 in the wild type). Theoretically, the positive control exerted on sucrose biosynthesis should be numerically identical to the negative control on starch biosynthesis unless additional metabolic pathways are affected. The rate of dark respiration showed some correlation with the TPT activity in that it increased in FtTPT overexpressors, but decreased in alpha TPTplants with an apparent control coefficient of C-TPT(JRes) = 0.24. If the control on sucrose biosynthesis is referred to as "gain of carbon" (positive control) and the control on starch biosynthesis as well as dark respiration as a "loss of carbon" (negative control) for sucrose biosynthesis and subsequent export, the sum of the control coefficients on dark respiration and starch biosynthesis would be numerically similar to the control coefficient on the rate of sucrose biosynthesis. There was also some control on the rate of photosynthetic electron transport, but only at high light and in elevated CO2 combined with low O-2 The control coefficient for the rate of photosynthetic electron transport was C-TPT(JETR) = 0.16 in the wild type. Control coefficients were also calculated for plants with elevated and lowered TPT activity. Furthermore, the extent to which starch degradation/glucoseutilisation compensates for the lack of triose phosphate export was assessed. The TPT also exerted control on metabolite contents in air.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 06/04/20 alle ore 01:56:12