Alteration by thioredoxin f over-expression of primary carbon metabolism and its response to elevated CO2 in tobacco (Nicotiana tabacum L.)
Thioredoxins f (Trx f) are chloroplastic proteins that have been shown to be essential for the redox-based regulation of several steps of carbon assimilation, such as the Calvin-Benson-Bassham cycle. However, the effective impact of Trx f activity on photosynthetic performance and carbon primary metabolism, including under varying CO<inf>2</inf> mole fraction, is not well documented. In this study, we provide a physiological and metabolomic characterization of leaves in transplastomic Trx f over-expressing tobacco (Nicotiana tabacum L., cv. Petit Havana SR1) grown under either ambient or elevated CO<inf>2</inf> (400 or 800μmolmol<sup>-1</sup>). Trx f overexpression strongly increased starch synthesis under both ambient and elevated CO<inf>2</inf> but was not accompanied by a stimulation of net photosynthetic CO<inf>2</inf> fixation. Rather, Trx f-overexpressing plants had a lower photorespiration rate due to an increase in internal (mesophyll) conductance for CO<inf>2</inf> (with the consequent increase in CO<inf>2</inf> mole fraction at the carboxylation site, c<inf>c</inf>), and a higher decrease (compared with the wild-type) in total photosynthetic electron flux upon acclimation to elevated CO<inf>2</inf>. There were also changes in a number of metabolites, such as enrichment in sugar phosphates and free phosphate, and depletion in alanine, threonine and free sugars. Our results suggest that over-expressing Trx f has an influence on chloroplastic metabolism by simultaneously stimulating the carboxylation-to-oxygenation ratio and starch synthesis, with side effects on amino acid metabolism. The potential mechanisms involved are discussed.
| Main Authors: | , , , , , , , , |
|---|---|
| Other Authors: | |
| Format: | artículo biblioteca |
| Published: |
Elsevier
2015-10
|
| Subjects: | Metabolomics, Photosynthesis, Rubisco, Thioredoxin f, Tobacco, |
| Online Access: | http://hdl.handle.net/10261/126235 http://dx.doi.org/10.13039/501100003329 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|