Elevated CO 2 alters tissue balance of nitrogen metabolism and downregulates nitrogen assimilation and signalling gene e
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ORIGINAL ARTICLE
Elevated CO2 alters tissue balance of nitrogen metabolism and downregulates nitrogen assimilation and signalling gene expression in wheat seedlings receiving high nitrate supply Sandeep B. Adavi 1 & Lekshmy Sathee 1 Received: 3 May 2020 / Accepted: 5 October 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Tissue and canopy-level evidence suggests that elevated carbon dioxide (EC) inhibits shoot nitrate assimilation in plants and thereby affects nitrogen (N) and protein content of the economic produce. It is speculated that species or genotypes relying more on root nitrate assimilation can adapt better under EC due to the improved/steady supply of reductants required for nitrate assimilation. A study was conducted to examine the effect of EC on N assimilation and associated gene expression in wheat seedlings. Wheat genotypes, BT-Schomburgk (BTS) with comparatively high leaf nitrate reductase (NR) activity and Gluyas Early (GE) with high root NR activity were grown in hydroponic culture for 30 days with two different nitrate levels (0.05 mM and 5 mM) in the climate controlled growth chambers maintained at either ambient (400 ± 10 μmol mol−1) or EC (700 ± 10 μmol mol−1) conditions. Exposure to EC downregulated the activity of enzyme NR and glutamate synthase (GOGAT) in leaf tissues, whereas in roots, activities of both the enzymes were upregulated by exposure to EC. In addition, EC downregulated N assimilation and signalling gene expression under high N availability. Root N assimilation was less affected in comparison with shoot N assimilation; thereby, the proportion of root contribution towards total assimilation was higher. The results suggest that EC could alter and re-programme N assimilation and signalling in wheat seedlings. The genotype and tissue-specific effects of EC on N assimilation also warrants the need for identification of suitable genotypes and revision of fertiliser regime for tapping the beneficial effects of EC conditions. Keywords Elevated CO2 . Nitrogen assimilation . Nitrogen signalling
Introduction Carbon dioxide (CO2), a major atmospheric factor which influences the crop productivity, is increasing at a faster rate and is projected to cross 700 μmol mol−1 by 2050 and reach 650– 1200 μmol mol−1 by the end of 2100 (Porter et al. 2014). A classical experiment by Kimball et al. (2001) showed an Sandeep B. Adavi and Lekshmy Sathee contributed equally to this work. Handling Editor: Néstor Carrillo Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00709-020-01564-3) contains supplementary material, which is available to authorized users. * Lekshmy Sathee [email protected] 1
Division of Plant Physiology, ICAR-Indian Agricultural Research Institute, New Delhi, India
increase of 10–143% in biomass of several C3 crops in response to elevated CO2 (EC). Nutrient availability is a probable constraint that partly explicates the inability of numerous plant species to maintain the much-expected higher growth rat
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