TY - JOUR

T1 - Alteration by thioredoxin f over-expression of primary carbon metabolism and its response to elevated CO2 in tobacco (Nicotiana tabacum L.)

AU - Aranjuelo, Iker

AU - Tcherkez, Guillaume

AU - Jauregui, Iván

AU - Gilard, Françoise

AU - Ancín, María

AU - Millán, Alicia Fernández-san

AU - Larraya, Luis

AU - Veramendi, Jon

AU - Farran, Inmaculada

PY - 2015/10

Y1 - 2015/10

N2 - 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 CO2 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 CO2 (400 or 800 μmol mol−1). Trx f overexpression strongly increased starch synthesis under both ambient and elevated CO2 but was not accompanied by a stimulation of net photosynthetic CO2 fixation. Rather, Trx f-overexpressing plants had a lower photorespiration rate due to an increase in internal (mesophyll) conductance for CO2 (with the consequent increase in CO2 mole fraction at the carboxylation site, cc), and a higher decrease (compared with the wild-type) in total photosynthetic electron flux upon acclimation to elevated CO2. 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.

AB - 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 CO2 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 CO2 (400 or 800 μmol mol−1). Trx f overexpression strongly increased starch synthesis under both ambient and elevated CO2 but was not accompanied by a stimulation of net photosynthetic CO2 fixation. Rather, Trx f-overexpressing plants had a lower photorespiration rate due to an increase in internal (mesophyll) conductance for CO2 (with the consequent increase in CO2 mole fraction at the carboxylation site, cc), and a higher decrease (compared with the wild-type) in total photosynthetic electron flux upon acclimation to elevated CO2. 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.

KW - Metabolomics

KW - Photosynthesis

KW - Rubisco

KW - Thioredoxin f

KW - Tobacco

U2 - 10.1016/j.envexpbot.2015.05.008

DO - 10.1016/j.envexpbot.2015.05.008

M3 - Journal article

VL - 118

SP - 40

EP - 48

JO - Environmental and Experimental Botany

JF - Environmental and Experimental Botany

SN - 0098-8472

ER -