Ontogenic changes of thioredoxins <em>f</em> and <em>m</em>, and other targets fructose-1,6-bisphosphatase and NAD(P)-malate dehydrogenase, of pea plants grown under light stress conditions.
In: New Phytologist, Jg. 145 (2000), Heft 1, S. 21-28
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Zugriff:
The transcript (mRNA) level and the protein content (as determined by enzyme-linked immunosorbent assay) of thioredoxins (Trx) f and m , and of their targets, chloroplast fructose-1,6-bisphosphatase (FBPase) and NAD(P)-malate dehydrogenase (NADP-MDH), increase over the ontogeny of pea plants grown under normal conditions showing their highest values before flowering (40 d growth). The clearest results appear in apical, but also in middle leaves. Enzyme activities of FBPase and NADP-MDH, were lowest just before flowering. In the case of FBPase this was probably a mechanism to facilitate triose-phosphate export to the cytosol for sucrose synthesis. The likely function of NADP-MDH is to supply the cytosol, via the malate translocator, with the NAD(P)H necessary for UTP regeneration in the sucrose biosynthetic pathway. Both the Fv/Fm ratio and the net photosynthetic rate (IRGA) decreased at saturating irradiance (16 h photoperiod) and under sub-saturating continuous light. However, the Fv/Fm quotient recovered to normal values after several days adaptation to high light. A similar recovery was also observed in net photosynthesis, although normal levels were never obtained. Under light-stress conditions the concentration of Trxs f and m , and of the targets FBPase and NADP-MDH, were somewhat lower than those of unstressed plants. Even though the levels of the corresponding transcripts (mRNAs) are similar in upper leaves from control and light-stressed plants, those of the middle and basal leaves from plants grown under high light were substantially higher than those of the control plants. In addition to the well-documented transcriptional regulation of nuclear-coded chloroplast proteins, these results seem to indicate the existence of an existence of an additional post-transcriptional control. [ABSTRACT FROM AUTHOR]
Titel: |
Ontogenic changes of thioredoxins <em>f</em> and <em>m</em>, and other targets fructose-1,6-bisphosphatase and NAD(P)-malate dehydrogenase, of pea plants grown under light stress conditions.
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Autor/in / Beteiligte Person: | Pagano, Eduardo A. ; Chueca, Ana ; Hermoso, Rosario ; Jose Lazaro, Juan ; Lopez-Gorge, Julio |
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Zeitschrift: | New Phytologist, Jg. 145 (2000), Heft 1, S. 21-28 |
Veröffentlichung: | 2000 |
Medientyp: | academicJournal |
ISSN: | 0028-646X (print) |
DOI: | 10.1046/j.1469-8137.2000.00561.x |
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