Elevated CO2 and water availability effect on gas exchange and nodule development in N2-fixing alfalfa plants

N2-fixing alfalfa plants were grown in controlled conditions at different CO2 levels (350 μmol mol−1versus 700 μmol mol−1) and water-availability conditions (WW, watered at maximum pot water capacity versus WD, watered at 50% of control treatments) in order to determine the CO2 effect (and applied a...

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Bibliographic Details
Authors: Aranjuelo, I. (Iker)|||/items/0b4d2aa2-f67b-4c8a-aca2-0cb34b171630, Irigoyen-Iparrea, J.J. (Juan Jose)|||/items/8ef56456-59a7-4eba-b376-37328752e352, Nogues, S. (Salvador)|||/items/a76bc37e-fce1-41c4-a613-34a820f8de6b, Sanchez-Diaz, M. (Manuel)|||/items/2f6c4b7b-a737-4d01-83c3-f311de625562
Format: article
Publication Date:2009
Country:España
Institution:Universidad de Navarra
Repository:Dadun. Depósito Académico Digital de la Universidad de Navarra
Language:English
OAI Identifier:oai:dadun.unav.edu:10171/23155
Online Access:https://hdl.handle.net/10171/23155
Access Level:Open access
Keyword:C sink strength
Climate change
Medicago sativa
Nodule metabolism
Photosynthetic acclimation
Acclimation
Description
Summary:N2-fixing alfalfa plants were grown in controlled conditions at different CO2 levels (350 μmol mol−1versus 700 μmol mol−1) and water-availability conditions (WW, watered at maximum pot water capacity versus WD, watered at 50% of control treatments) in order to determine the CO2 effect (and applied at two water regimes) on plant growth and nodule activity in alfalfa plants. The CO2 stimulatory effect (26% enhancement) on plant growth was limited to WW plants, whereas no CO2 effect was observed in WD plants. Exposure to elevated CO2 decreased Rubisco carboxylation capacity of plants, caused by a specific reduction in Rubisco (EC 4.1.1.39) concentration (11% in WW and 43% in WD) probably explained by an increase in the leaf carbohydrate levels. Plants grown at 700 μmol mol−1 CO2 maintained control photosynthetic rates (at growth conditions) by diminishing Rubisco content and by increasing nitrogen use efficiency. Interestingly, our data also suggest that reduction in shoot N demand (reflected by the TSP and especially Rubisco depletion) affected negatively nodule activity (malate dehydrogenase, EC 1.1.1.37, and glutamate-oxaloacetate transaminase, EC 2.6.1.1, activities) particularly in water-limited conditions. Furthermore, nodule DM and TSS data revealed that those nodules were not capable to overcome C sink strength limitations.

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