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Higher atmospheric CO2 levels favour C3 plants over C4 plants in utilizing ammonium as a nitrogen source

Wang, Feng and Gao, Jingwen and Yong, Jean W.H and Wang, Qiang and Ma, Jungwei and He, Xinhua (2021). Higher atmospheric CO2 levels favour C3 plants over C4 plants in utilizing ammonium as a nitrogen source. Frontiers in Plant Science. 11 , 537443
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Abstract

Photosynthesis of wheat and maize declined when grown with NH4+ as a nitrogen (N) source at ambient CO2 concentration compared to those grown with a mixture of NO3– and NH4+, or NO3– as the sole N source. Interestingly, these N nutritional physiological responses changed when the atmospheric CO2 concentration increases. We studied the photosynthetic responses of wheat and maize growing with various N forms at three levels of growth CO2 levels. Hydroponic experiments were carried out using a C3 plant (wheat, Triticum aestivum L. cv. Chuanmai 58) and a C4 plant (maize, Zea mays L. cv. Zhongdan 808) given three types of N nutrition: sole NO3– (NN), sole NH4+ (AN) and a mixture of both NO3– and NH4+ (Mix-N). The test plants were grown using custom-built chambers where a continuous and desired atmospheric CO2 (Ca) concentration could be maintained: 280 μmol mol–1 (representing the pre-Industrial Revolution CO2 concentration of the 18th century), 400 μmol mol–1 (present level) and 550 μmol mol–1 (representing the anticipated futuristic concentration in 2050). Under AN, the decrease in net photosynthetic rate (Pn) was attributed to a reduction in the maximum RuBP-regeneration rate, which then caused reductions in the maximum Rubisco-carboxylation rates for both species. Decreases in electron transport rate, reduction of electron flux to the photosynthetic carbon [Je(PCR)] and electron flux for photorespiratory carbon oxidation [Je(PCO)] were also observed under AN for both species. However, the intercellular (Ci) and chloroplast (Cc) CO2 concentration increased with increasing atmospheric CO2 in C3 wheat but not in C4 maize, leading to a higher Je(PCR)/ Je(PCO) ratio. Interestingly, the reduction of Pn under AN was relieved in wheat through higher CO2 levels, but that was not the case in maize. In conclusion, elevating atmospheric CO2 concentration increased Ci and Cc in wheat, but not in maize, with enhanced electron fluxes towards photosynthesis, rather than photorespiration, thereby relieving the inhibition of photosynthesis under AN. Our results contributed to a better understanding of NH4+ involvement in N nutrition of crops growing under different levels of CO2.

Authors/Creators:Wang, Feng and Gao, Jingwen and Yong, Jean W.H and Wang, Qiang and Ma, Jungwei and He, Xinhua
Title:Higher atmospheric CO2 levels favour C3 plants over C4 plants in utilizing ammonium as a nitrogen source
Series Name/Journal:Frontiers in Plant Science
Year of publishing :2021
Volume:11
Article number:537443
Number of Pages:16
ISSN:1664-462X
Language:English
Publication Type:Journal article
Article category:Scientific peer reviewed
Version:Published version
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science
(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Botany
(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Climate Research
Keywords:atmospheric CO2, ecophysiology, electron transport, NH4C stress, photosynthesis, Triticum aestivum, Zea mays
URN:NBN:urn:nbn:se:slu:epsilon-p-108503
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-108503
Additional ID:
Type of IDID
DOI10.3389/fpls.2020.537443
Otherhttps://doi.org/10.3389/fpls.2020.537443
ID Code:19115
Faculty:LTV - Fakulteten för landskapsarkitektur, trädgårds- och växtproduktionsvetenskap
Department:(LTJ, LTV) > Department of Biosystems and Technology (from 130101)
Deposited By: SLUpub Connector
Deposited On:07 Dec 2020 07:23
Metadata Last Modified:07 Dec 2020 07:31

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