Elevated carbon dioxide and chronic warming together decrease nitrogen uptake rate, net translocation, and assimilation in tomato

Authors: JAYAWARDENA, DILEEPA - University Of Toledo; HECKATHORN, SCOTT - University Of Toledo; RAJANAYAKE, KRISHANI - University Of Toledo; Boldt, Jennifer; ISAILOVIC, DRAGAN - University Of Toledo

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2021
Publication Date: 4/8/2021
Citation: Jayawardena, D.M., Heckathorn, S.A., Rajanayake, K., Boldt, J.K., Isailovic, D. 2021. Elevated carbon dioxide and chronic warming together decrease nitrogen uptake rate, net translocation, and assimilation in tomato. Plants. 10(4):Article 722. https://doi.org/10.3390/plants10040722.
DOI: https://doi.org/10.3390/plants10040722

Interpretive Summary: Global climate models predict atmospheric carbon dioxide (CO2) concentration and average surface temperature will continue to rise during this century, which may increase acute and chronic stress in plants. Identifying how the combined impact of elevated temperature and CO2 reduces shoot nitrogen concentration has important implications for crop nutritional quality, fertilizer use, and crop improvement. In tomato (Solanum lycopericum), a warm-season crop, we discovered that roots had lower nitrogen uptake, lower net nitrogen movement from the roots up to the shoot (translocation), and less whole-plant nitrogen incorporation (assimilation) when plants were grown under the combination of elevated temperature and elevated CO2. This is likely due to reduced nitrogen uptake and fewer nitrogen assimilation proteins, rather than root resource limitations or protein damage under these conditions. This information provides valuable insight to the weak links in nitrogen metabolism in response to CO2 enrichment and global warming that can be targeted for improvement when developing new crop cultivars that are more resilient to these expected climate conditions.

Technical Abstract: The response of plant nitrogen (N) relations to the combination of elevated CO2 (eCO2) and warming are poorly understood. To study this, tomato (Solanum lycopersicum) plants were grown at 400 or 700 ppm CO2 and 33/28 or 38/33 oC (day/night), and their soil was labeled with 15NO3- or 15NH4+. Plant dry mass, root N-uptake rate, root-to-shoot net N translocation, whole-plant N assimilation, and root resource availability (%C, %N, total non-structural carbohydrates) were measured. Relative to eCO2 or warming alone, eCO2 + warming decreased growth, NO3- and NH4+ -uptake rates, root-to-shoot net N translocation, and whole-plant N assimilation. Decreased N assimilation with eCO2 + warming was driven mostly by inhibition of NO3- assimilation, and was not associated with root resource limitations or damage to N-assimilatory proteins. Previously, we showed in tomato that eCO2 + warming decreases the concentration of N-uptake and assimilatory proteins in roots and dramatically increases leaf angle, which decreases whole-plant light capture and, hence, photosynthesis and growth. Thus, decreases in N uptake and assimilation with eCO2 + warming in tomato are likely due to reduced plant N demand.