Higher Atmospheric CO2 Levels Favor C-3 Plants Over C-4 Plants in Utilizing Ammonium as a Nitrogen Source

文献类型： 外文期刊

第一作者： Wang, Feng

作者： Wang, Feng;Gao, Jingwen;Wang, Qiang;Ma, Junwei;Wang, Feng;He, Xinhua;Wang, Feng;Gao, Jingwen;Yong, Jean W. H.;He, Xinhua;Yong, Jean W. H.

作者机构：

关键词： atmospheric CO2; ecophysiology; electron transport; NH4+ stress; photosynthesis; Triticum aestivum; Zea mays

期刊名称：FRONTIERS IN PLANT SCIENCE （ 影响因子：5.753； 五年影响因子：6.612 ）

ISSN： 1664-462X

年卷期： 2020 年 11 卷

页码：

收录情况： SCI

摘要： 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 C-3 plant (wheat, Triticum aestivum L. cv. Chuanmai 58) and a C-4 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 (C-a) concentration could be maintained: 280 mu mol mol(-1) (representing the pre-Industrial Revolution CO2 concentration of the 18th century), 400 mu mol mol(-1) (present level) and 550 mu mol mol(-1) (representing the anticipated futuristic concentration in 2050). Under AN, the decrease in net photosynthetic rate (P-n) 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 (C-i) and chloroplast (C-c) CO2 concentration increased with increasing atmospheric CO2 in C-3 wheat but not in C-4 maize, leading to a higher Je(PCR)/ Je(PCO) ratio. Interestingly, the reduction of P-n 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 C-i and C-c 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.

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