1
|
Gong J, Zhang Z, Wang B, Shi J, Zhang W, Dong Q, Song L, Li Y, Liu Y. N addition rebalances the carbon and nitrogen metabolisms of Leymus chinensis through leaf N investment. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 185:221-232. [PMID: 35714430 DOI: 10.1016/j.plaphy.2022.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 04/26/2022] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
Intensifying nitrogen (N) deposition disturbs the growth of grassland plants due to an imbalance between their carbon (C) and N metabolism. However, it's unclear how plant physiological strategies restore balance. We investigated the effects of multiple N addition levels (0-25 g N m-2 yr-1) on the coordination of C and N metabolism in a dominant grass (Leymus chinensis) in a semiarid grassland in northern China. To do so, we evaluated photosynthetic parameters, leaf N allocation, C- and N-based metabolites, and metabolic enzymes. We found that a moderate N level (10 g N m-2 yr-1) promoted carboxylation and electron transport by allocating more N to the photosynthetic apparatus and increasing ribulose bisphosphate carboxylase/oxygenase activity, thereby increasing photosynthetic capacity. The highest N level (25 g N m-2 yr-1) promoted N investment in nonphotosynthetic pathways and increased the free amino acids in the leaves. N addition stimulated the accumulation of C and N compounds across organs by activating sucrose phosphate synthase, nitrate reductase, and glutamine synthetase. This enhancement triggered a transformation of primary metabolites (nonstructural carbohydrates, proteins, amino acids) to secondary metabolites (flavonoids, phenols, and alkaloids) for temporary storage or as defense compounds. Citric acid, as the C skeleton for enhanced N metabolism, decreased significantly, and malic acid increased by catalysis of phosphoenolpyruvate carboxylase. Our findings show the adaptability of L. chinensis to different N-addition levels by adjusting its allocations of C and N metabolic compounds and confirm the roles of C and N coordination by grassland plants in these adaptations.
Collapse
Affiliation(s)
- Jirui Gong
- State Key Laboratory of Earth Surface Processes and Resource Ecology, School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China.
| | - Zihe Zhang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China.
| | - Biao Wang
- College of Materials Science and Engineering, College of Architecture and Urban Planning, Chongqing Jiaotong University, Chongqing, 400074, China.
| | - Jiayu Shi
- State Key Laboratory of Earth Surface Processes and Resource Ecology, School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China.
| | - Weiyuan Zhang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China.
| | - Qi Dong
- State Key Laboratory of Earth Surface Processes and Resource Ecology, School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China.
| | - Liangyuan Song
- State Key Laboratory of Earth Surface Processes and Resource Ecology, School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China.
| | - Ying Li
- State Key Laboratory of Earth Surface Processes and Resource Ecology, School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China.
| | - Yingying Liu
- State Key Laboratory of Earth Surface Processes and Resource Ecology, School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing 100875, China.
| |
Collapse
|
2
|
He J, Qin L. Impacts of Reduced Nitrate Supply on Nitrogen Metabolism, Photosynthetic Light-Use Efficiency, and Nutritional Values of Edible Mesembryanthemum crystallinum. FRONTIERS IN PLANT SCIENCE 2021; 12:686910. [PMID: 34149787 PMCID: PMC8213338 DOI: 10.3389/fpls.2021.686910] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 05/06/2021] [Indexed: 05/13/2023]
Abstract
Mesembryanthemum crystallinum (common ice plant), as a nutritious ready-to-eat salad in Singapore, has become popular in recent years. However, basic data about the impacts of NO3 - supply on its NO3 - accumulation and nutritional quality are lacking. In this study, all plants were first grown indoor hydroponically in 10% artificial seawater (ASW) with modified full-strength Netherlands Standard Composition nutrient solution for 11 days, before transferring them to different reduced NO3 - solutions. All plants grew well and healthy after 7 days of treatment. However, plants grown with 3/4 N and 1/2 N were bigger with higher shoot and root fresh weight (FW), greater leaf number, and total leaf area (TLA) than those grown with full nitrogen (N), 1/4 N, and 0 N. Mesembryanthemum crystallinum grown with full N, 3/4 N, and 1/4 N had similar specific leaf area (SLA), while 0 N plants had significantly lower SLA. All plants had similar leaf succulence (LS). However, leaf water content (LWC) was lower, while leaf dry matter accumulation (LDMC) was higher in 0 N plants after 7 days of treatment. Compared with plants grown with full N, shoot NO3 - concentrations in 3/4 N, 1/2 N, and 1/4 N plants were constant or slightly increased during the treatments. For 0 N plants, shoot NO3 - concentration decreased significantly during the treatment compared with other plants. Shoot NO3 - accumulation was associated with nitrate reductase activity (NRA). For instance, after 7 days of treatment, shoot NO3 - concentration and NRA on a FW basis in 0 N plants were, respectively, 45 and 31% of full N plants. After transferring full N to 0 N for 7 days, all M. crystallinum had higher chlorophyll (Chl) content coupled with higher electron transport rate (ETR) and higher effective quantum yield of PSII, while full N plants had higher non-photochemical quenching (NPQ). The 0N plants had much higher concentrations of proline, total soluble sugar (TSS), and total ascorbic acid (ASC) than other plants. In conclusion, totally withdrawing NO3 - from the growth media prior to harvest could be one of the strategies to reduce shoot NO3 - concentration. Reduced NO3 - supply further enhanced nutritional values as concentrations of proline, TSS, and ASC were enhanced markedly in M. crystallinum plants after transferring them from full N to 0 N.
Collapse
Affiliation(s)
- Jie He
- National Institute of Education, Nanyang Technological University, Singapore, Singapore
| | | |
Collapse
|