Elevated CO2 differentially regulates root nitrate transporter kinetics in a genotype and nitrate dose-dependent manner. (April 2021)

• Record Type: Journal Article
• Authors: Adavi, Sandeep B.; Sathee, Lekshmy
• Is Part Of: Plant science. Volume 305(2021)
• Publication Date: 2021-04
• Subjects: Nitrate uptake kinetics -- Elevated CO2 -- Wheat -- Low affinity nitrate transport system -- High affinity nitrate transport system -- Km -- Vmax; Botany -- Periodicals; Botanique -- Périodiques; 580
• DOI: 10.1016/j.plantsci.2020.110807
• Languages: English
• ISSNs: 0168-9452

Abstract

Highlights: Wheat seedlings grown under elevated CO2 displayed significant changes in nitrate uptake kinetic components. Elevated CO2 enhanced the production of nitric oxide in wheat seedlings receiving high nitrate supply. Induction in rate of uptake by exogenous nitric oxide treatment was significantly lower in elevated CO2 . Elevated CO2 also hindered nitrogen assimilation, however wheat genotype with high leaf nitrate assimilation capacity was able to maintain nitrate uptake rate under elevated CO2 albeit at lower level in comparison to control. Abstract: The nitrogen (N) and protein concentration of wheat crop and grain often decline as a result of exposure of the crop to elevated CO2 (EC). In our earlier studies, it was found that the exacerbated production of nitric oxide (NO) represses the transcription of nitrate reductase (NR) and high affinity nitrate transporters (HATS) in EC grown wheat seedlings receiving high N. High N supply under EC also resulted in accumulation of reactive oxygen species (ROS), and reactive nitrogen species (RNS; NO and S- nitrosothiols) ensuing faster senescence and reduced N metabolite concentration in wheat. In this study, the effect of short-term exposure to EC on nitrate uptake kinetics was studied. The impact of EC on constitutive and inducible components of high affinity and low affinity nitrate uptake systems (HATS and LATS) were delineated in two wheat genotypes diverse in terms of nitrate uptake and assimilation capacities. Nitrate dose-response of NR was suppressed by EC in both leaf and root tissues. Plants grown under EC displayed a marked reduction in nitrate uptake kinetic components of LATS. Wheat genotype with high leaf nitrate assimilation capacity was able to maintain considerably higher nitrate uptake rate under EC albeit at a lower rate in comparison to ambient CO2 . Wheat leaves exposed to EC displayed a comparatively higher abundance of NO and showed incremental abundance depending on increase in nitrate supply. Exogenous NO supply significantly suppressed the nitrate uptake rate of EC grown plants. Hence, EC-induced production of NO downregulates LATS kinetics in a genotype and nitrate dose-dependent manner.