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Xia A, Wu Y, Xiang J, Yin H, Ming J, Qin Z. Quantification of Glucose Metabolism and Nitrogen Utilization in Two Brassicaceae Species under Bicarbonate and Variable Ammonium Soil Conditions. PLANTS (BASEL, SWITZERLAND) 2023; 12:3095. [PMID: 37687342 PMCID: PMC10489622 DOI: 10.3390/plants12173095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 08/15/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023]
Abstract
In karst habitats under drought conditions, high bicarbonate (high pH), and an abundant nitrate soil environment, bicarbonate regulates the glycolysis (EMP) and pentose phosphate pathways (PPP), which distribute ATP and NADPH, affecting nitrate (NO3-) and ammonium (NH4+) utilization in plants. However, the relationship between EMP PPP and NO3-, and NH4+ utilization and their responses to bicarbonate and variable ammonium still remains elusive. In this study, we used Brassica napus (Bn, a non-karst-adaptable plant) and Orychophragmus violaceus (Ov, a karst-adaptable plant) as plant materials, employed a bidirectional nitrogen-isotope-tracing method, and performed the quantification of the contribution of EMP and PPP. We found that bicarbonate and ammonium inhibited glucose metabolism and nitrogen utilization in Bn under simulated karst habitats. On the other hand, it resulted in a shift from EMP to PPP to promote ammonium utilization in Ov under high ammonium stress in karst habitats. Compared with Bn, bicarbonate promoted glucose metabolism and nitrogen utilization in Ov at low ammonium levels, leading to an increase in photosynthesis, the PPP, carbon and nitrogen metabolizing enzyme activities, nitrate/ammonium utilization, and total inorganic nitrogen assimilation capacity. Moreover, bicarbonate significantly reduced the growth inhibition of Ov by high ammonium, resulting in an improved PPP, RCRUBP, and ammonium utilization to maintain growth. Quantifying the relationships between EMP, PPP, NO3-, and NH4+ utilization can aid the accurate analysis of carbon and nitrogen use efficiency changes in plant species. Therefore, it provides a new prospect to optimize the nitrate/ammonium utilization in plants and further reveals the differential responses of inorganic carbon and nitrogen (C-N) metabolism to bicarbonate and variable ammonium in karst habitats.
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Affiliation(s)
- Antong Xia
- Enshi Tujia & Miao Autonomous Prefecture Academy of Agricultural Sciences, Enshi 445000, China; (A.X.)
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Yanyou Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Jiqian Xiang
- Enshi Tujia & Miao Autonomous Prefecture Academy of Agricultural Sciences, Enshi 445000, China; (A.X.)
| | - Hongqing Yin
- Enshi Tujia & Miao Autonomous Prefecture Academy of Agricultural Sciences, Enshi 445000, China; (A.X.)
| | - Jiajia Ming
- Enshi Tujia & Miao Autonomous Prefecture Academy of Agricultural Sciences, Enshi 445000, China; (A.X.)
| | - Zhanghui Qin
- Enshi Tujia & Miao Autonomous Prefecture Academy of Agricultural Sciences, Enshi 445000, China; (A.X.)
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Martínez-Peña R, Vergara-Díaz O, Schlereth A, Höhne M, Morcuende R, Nieto-Taladriz MT, Araus JL, Aparicio N, Vicente R. Analysis of durum wheat photosynthetic organs during grain filling reveals the ear as a water stress-tolerant organ and the peduncle as the largest pool of primary metabolites. PLANTA 2023; 257:81. [PMID: 36917306 PMCID: PMC10014764 DOI: 10.1007/s00425-023-04115-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 03/04/2023] [Indexed: 06/18/2023]
Abstract
The pool of carbon- and nitrogen-rich metabolites is quantitatively relevant in non-foliar photosynthetic organs during grain filling, which have a better response to water limitation than flag leaves. The response of durum wheat to contrasting water regimes has been extensively studied at leaf and agronomic level in previous studies, but the water stress effects on source-sink dynamics, particularly non-foliar photosynthetic organs, is more limited. Our study aims to investigate the response of different photosynthetic organs to water stress and to quantify the pool of carbon and nitrogen metabolites available for grain filling. Five durum wheat varieties were grown in field trials in the Spanish region of Castile and León under irrigated and rainfed conditions. Water stress led to a significant decrease in yield, biomass, and carbon and nitrogen assimilation, improved water use efficiency, and modified grain quality traits in the five varieties. The pool of carbon (glucose, glucose-6-phosphate, fructose, sucrose, starch, and malate) and nitrogen (glutamate, amino acids, proteins and chlorophylls) metabolites in leaf blades and sheaths, peduncles, awns, glumes and lemmas were also analysed. The results showed that the metabolism of the blades and peduncles was the most susceptible to water stress, while ear metabolism showed higher stability, particularly at mid-grain filling. Interestingly, the total metabolite content per organ highlighted that a large source of nutrients, which may be directly involved in grain filling, are found outside the blades, with the peduncles being quantitatively the most relevant. We conclude that yield improvements in our Mediterranean agro-ecosystem are highly linked to the success of shoots in producing ears and a higher number of grains, while grain filling is highly dependent on the capacity of non-foliar organs to fix CO2 and N. The ear organs show higher stress resilience than other organs, which deserves our attention in future breeding programmes.
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Affiliation(s)
- Raquel Martínez-Peña
- Cereals Group, Section of Herbaceous, Agro-Technological Institute of Castile and León, Junta de Castile and León, Valladolid, Spain
| | - Omar Vergara-Díaz
- Plant Ecophysiology and Metabolism Group, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Oeiras, Portugal
| | - Armin Schlereth
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Melanie Höhne
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Rosa Morcuende
- Institute of Natural Resources and Agrobiology of Salamanca (IRNASA), Consejo Superior de Investigaciones Científicas (CSIC), Salamanca, Spain
| | - María Teresa Nieto-Taladriz
- Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - José Luis Araus
- Integrative Crop Ecophysiology Group, Section of Plant Physiology, Faculty of Biology, University of Barcelona, Barcelona, and AGROTECNIO-CERCA Center, Lleida, Spain
| | - Nieves Aparicio
- Cereals Group, Section of Herbaceous, Agro-Technological Institute of Castile and León, Junta de Castile and León, Valladolid, Spain
| | - Rubén Vicente
- Plant Ecophysiology and Metabolism Group, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Oeiras, Portugal.
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany.
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Hu Y, Guy RD, Soolanayakanahally RY. Nitrogen isotope discrimination in open-pollinated and hybrid canola suggests indirect selection for enhanced ammonium utilization. FRONTIERS IN PLANT SCIENCE 2022; 13:1024080. [PMID: 36438099 PMCID: PMC9691982 DOI: 10.3389/fpls.2022.1024080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 10/25/2022] [Indexed: 06/16/2023]
Abstract
Nitrogen isotope discrimination (Δ15N) may have utility as an indicator of nitrogen use in plants. A simple Δ15N-based isotope mass balance (IMB) model has been proposed to provide estimates of efflux/influx (E/I) ratios across root plasma membranes, the proportion of inorganic nitrogen assimilation in roots (P root) and translocation of inorganic nitrogen to shoots (Ti/Tt) under steady-state conditions. We used the IMB model to investigate whether direct selection for yield in canola (Brassica napus L.) has resulted in indirect selection in traits related to nitrogen use. We selected 23 canola lines developed from 1942 to 2017, including open-pollinated (OP) lines developed prior to 2005 as well as more recent commercial hybrids (CH), and in three separate experiments grew them under hydroponic conditions in a greenhouse with either 0.5 mM ammonium, 0.5 mM nitrate, or 5 mM nitrate. Across all lines, E/I, Proot and Ti/Tt averaged 0.09±0.03, 0.82±0.05 and 0.23±0.06 in the low nitrate experiment, and 0.31±0.06, 0.71±0.07 and 0.42±0.12 in the high nitrate experiment, respectively. In contrast, in the ammonium experiment average E/I was 0.40±0.05 while Ti/Tt averaged 0.07±0.04 and Proot averaged 0.97±0.02. Although there were few consistent differences between OP and CH under nitrate nutrition, commercial hybrids were collectively better able to utilize ammonium as their sole nitrogen source, demonstrating significantly greater overall biomass and a lower Proot and a higher Ti/Tt, suggesting a somewhat greater flux of ammonium to the shoot. Average root and whole-plant Δ15N were also slightly higher in CH lines, suggesting a small increase in E/I. An increased ability to tolerate and/or utilize ammonium in modern canola hybrids may have arisen under intensive mono-cropping.
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Affiliation(s)
- Yi Hu
- Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Vancouver, BC, Canada
| | - Robert D. Guy
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Vancouver, BC, Canada
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Csilléry K, Buchmann N, Brendel O, Gessler A, Glauser A, Doris Kupferschmid A. Recovery of silver fir (Abies alba Mill.) seedlings from ungulate browsing mirrors soil nitrogen availability. TREE PHYSIOLOGY 2022; 42:273-288. [PMID: 34528673 DOI: 10.1093/treephys/tpab105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Abies alba (Mill.) has a high potential for mitigating climate change in European mountain forests; yet, its natural regeneration is severely limited by ungulate browsing. Here, we simulated browsing in a common garden experiment to study growth and physiological traits, measured from bulk needles, using a randomized block design with two levels of browsing severity and seedlings originating from 19 populations across Switzerland. Genetic factors explained most variation in growth (on average, 51.5%) and physiological traits (10.2%) under control conditions, while heavy browsing considerably reduced the genetic effects on growth (to 30%), but doubled those on physiological traits related to carbon storage. While browsing reduced seedling height, it also lowered seedling water-use efficiency (decreased $\delta ^{13}$C) and increased their $\delta ^{15}$N. Different populations reacted differently to browsing stress, and for seedling height, starch concentration and $\delta ^{15}$N, population differences appeared to be the result of natural selection. First, we found that populations originating from the warmest regions recovered the fastest from browsing stress, and they did so by mobilizing starch from their needles, which suggests a genetic underpinning for a growth-storage trade-off across populations. Second, we found that seedlings originating from mountain populations growing on steep slopes had a higher $\delta ^{15}$N in the common garden than those originating from flat areas, indicating that they have been selected to grow on N-poor, potentially drained, soils. This finding was corroborated by the fact that nitrogen concentration in adult needles was lower on steep slopes than on flat ground, strongly indicating that steep slopes are the most N-poor environments. These results suggest that adaptation to climate and soil nitrogen availability, as well as ungulate browsing pressure, co-determine the regeneration and range limit of silver fir.
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Affiliation(s)
- Katalin Csilléry
- Land Change Science, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
- Biodiversity and Conservation Biology, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Oliver Brendel
- UMR Silva, INRAE, AgroParisTech, Université de Lorraine, Nancy, France
| | - Arthur Gessler
- Forest Dynamics, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
- Institute of Terrestrial Ecosystems, ETH Zurich, Zurich, Switzerland
| | - Alexandra Glauser
- Forest Resources and Management, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
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5
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Jethva J, Schmidt RR, Sauter M, Selinski J. Try or Die: Dynamics of Plant Respiration and How to Survive Low Oxygen Conditions. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11020205. [PMID: 35050092 PMCID: PMC8780655 DOI: 10.3390/plants11020205] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 05/09/2023]
Abstract
Fluctuations in oxygen (O2) availability occur as a result of flooding, which is periodically encountered by terrestrial plants. Plant respiration and mitochondrial energy generation rely on O2 availability. Therefore, decreased O2 concentrations severely affect mitochondrial function. Low O2 concentrations (hypoxia) induce cellular stress due to decreased ATP production, depletion of energy reserves and accumulation of metabolic intermediates. In addition, the transition from low to high O2 in combination with light changes-as experienced during re-oxygenation-leads to the excess formation of reactive oxygen species (ROS). In this review, we will update our current knowledge about the mechanisms enabling plants to adapt to low-O2 environments, and how to survive re-oxygenation. New insights into the role of mitochondrial retrograde signaling, chromatin modification, as well as moonlighting proteins and mitochondrial alternative electron transport pathways (and their contribution to low O2 tolerance and survival of re-oxygenation), are presented.
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Affiliation(s)
- Jay Jethva
- Department of Plant Developmental Biology and Plant Physiology, Faculty of Mathematics and Natural Sciences, Botanical Institute, Christian-Albrechts University, D-24118 Kiel, Germany; (J.J.); (M.S.)
| | - Romy R. Schmidt
- Department of Plant Biotechnology, Faculty of Biology, University of Bielefeld, D-33615 Bielefeld, Germany;
| | - Margret Sauter
- Department of Plant Developmental Biology and Plant Physiology, Faculty of Mathematics and Natural Sciences, Botanical Institute, Christian-Albrechts University, D-24118 Kiel, Germany; (J.J.); (M.S.)
| | - Jennifer Selinski
- Department of Plant Cell Biology, Botanical Institute, Faculty of Mathematics and Natural Sciences, Christian-Albrechts University, D-24118 Kiel, Germany
- Correspondence: ; Tel.: +49-(0)431-880-4245
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6
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Hu Y, Guy RD, Soolanayakanahally RY. Genotypic variation in C and N isotope discrimination suggests local adaptation of heart-leaved willow. TREE PHYSIOLOGY 2022; 42:32-43. [PMID: 33517390 DOI: 10.1093/treephys/tpab010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 01/18/2021] [Indexed: 06/12/2023]
Abstract
Plants acquire multiple resources from the environment and may need to adjust and/or balance their respective resource-use efficiencies to maximize grow and survival, in a locally adaptive manner. In this study, tissue and whole-plant carbon (C) isotopic composition (δ13C) and carbon/nitrogen (C/N) ratios provided long-term measures of use efficiencies for water (WUE) and nitrogen (NUE), and a nitrogen (N) isotopic composition (δ15N)-based mass balance model was used to estimate traits related to N uptake and assimilation in heart-leaved willow (Salix eriocephala Michx.). In an initial common garden experiment consisting of 34 populations, we found population-level variation in δ13C, C/N ratio and δ15N, indicating different patterns in WUE, NUE and N uptake and assimilation. Although there was no relationship between foliar δ13C and C/N ratios among populations, there was a significant negative correlation between these measures across all individuals, implying a genetic and/or plastic trade-off between WUE and NUE not associated with local adaptation. To eliminate any environmental effect, we grew a subset of 21 genotypes hydroponically with nitrate as the sole N source and detected significant variation in δ13C, δ15N and C/N ratios. Variation in δ15N was mainly due to genotypic differences in the nitrate efflux/influx ratio (E/I) at the root. Both experiments suggested clinal variation in δ15N (and thus N uptake efficiency) with latitude of origin, which may relate to water availability and could contribute to global patterns in ecosystem δ15N. There was a tendency for genotypes with higher WUE to come from more water-replete sites with shorter and cooler growing seasons. We found that δ13C, C/N ratio and E/I were not inter-correlated, suggesting that the selection of growth, WUE, NUE and N uptake efficiency can occur without trade-off.
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Affiliation(s)
- Yi Hu
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Forest Sciences Centre, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Robert D Guy
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Forest Sciences Centre, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
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7
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Cui J, Peuke AD, Limami AM, Tcherkez G. Why is phloem sap nitrate kept low? PLANT, CELL & ENVIRONMENT 2021; 44:2838-2843. [PMID: 34075592 DOI: 10.1111/pce.14116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 05/10/2021] [Accepted: 05/23/2021] [Indexed: 06/12/2023]
Affiliation(s)
- Jing Cui
- Research School of Biology, ANU College of Science, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Andreas D Peuke
- ADP International Plant Science Consulting, Gundelfingen-Wildtal, Germany
| | - Anis M Limami
- Institut de Recherche en Horticulture et Semences, INRAe, Université d'Angers, Beaucouzé, France
| | - Guillaume Tcherkez
- Research School of Biology, ANU College of Science, Australian National University, Canberra, Australian Capital Territory, Australia
- Institut de Recherche en Horticulture et Semences, INRAe, Université d'Angers, Beaucouzé, France
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8
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Wang M, Yi S, Ju M, Yi X. Tracking Animal-Dispersed Seedlings Using 15N Xylem Injection Method. FRONTIERS IN PLANT SCIENCE 2021; 12:582530. [PMID: 33995426 PMCID: PMC8120291 DOI: 10.3389/fpls.2021.582530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 03/16/2021] [Indexed: 06/02/2023]
Abstract
Although various seed-marking methods have been developed for seed dispersal, it remains difficult to track the actual patterns of seed dispersal and seedling recruitment. Thus, new labeling methods that accurately track seedling establishment along with seed movement would help us better understand seed dispersal. Here, we developed a new nondestructive method using 15N xylem injection to track seed dispersal and seedling recruitment based on the enriched isotopic signals in the mature seeds. Our results first showed that xylem injection of 15N successfully enriched 15N both in the acorns and seedlings of Quercus variabilis. By marking acorns and seedlings with 15N stable isotopes, we successfully tracked seedlings established from acorns dispersed by seed-eating animals in the field. Our xylem 15N injection caused little alteration to seeds and showed no significant effects on seed selection by seed-eating animals as well as seed germination and seedling establishment, verifying the validity of the 15N xylem injection method to track seedling establishment. Our xylem 15N injection method is expected to be a powerful tool for tracking seed dispersal and seedling recruitment mediated by seed-eating animals in seed dispersal ecology.
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Affiliation(s)
- Minghui Wang
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Sijie Yi
- College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Mengyao Ju
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Xianfeng Yi
- College of Life Sciences, Qufu Normal University, Qufu, China
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9
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Foscari A, Leonarduzzi G, Incerti G. N uptake, assimilation and isotopic fractioning control δ 15N dynamics in plant DNA: A heavy labelling experiment on Brassica napus L. PLoS One 2021; 16:e0247842. [PMID: 33705458 PMCID: PMC7951814 DOI: 10.1371/journal.pone.0247842] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 02/12/2021] [Indexed: 12/02/2022] Open
Abstract
In last decades, a large body of evidence clarified nitrogen isotope composition (δ15N) patterns in plant leaves, roots and metabolites, showing isotopic fractionation along N uptake and assimilation pathways, in relation to N source and use efficiency, also suggesting 15N depletion in plant DNA. Here we present a manipulative experiment on Brassica napus var. oleracea, where we monitored δ 15N of purified, lyophilized DNA and source leaf and root materials, over a 60-days growth period starting at d 60 after germination, in plants initially supplied with a heavy labelled (δ 15NAir-N2 = 2100 mUr) ammonium nitrate solution covering nutrient requirements for the whole observation period (470 mg N per plant) and controlling for the labelled N species (ṄH4, ṄO3 and both). Dynamics of Isotopic Ratio Mass Spectrometry (IRMS) data for the three treatments showed that: (1) leaf and root δ 15N dynamics strictly depend on the labelled chemical species, with ṄH4, ṄO3 and ṄH4ṄO3 plants initially showing higher, lower and intermediate values, respectively, then converging due to the progressive NH4+ depletion from the nutrient solution; (2) in ṄH4ṄO3, where δ15N was not affected by the labelled chemical species, we did not observe isotopic fractionation associated to inorganic N uptake; (3) δ15N values in roots compared to leaves did not fully support patterns predicted by differences in assimilation rates of NH4+ and NO3-; (4) DNA is depleted in 15N compared to the total N pools of roots and leaves, likely due to enzymatic discrimination during purine biosynthesis. In conclusion, while our experimental setup did not allow to assess the fractionation coefficient (ε) associated to DNA bases biosynthesis, this is the first study specifically reporting on dynamics of specific plant molecular pools such as nucleic acids over a long observation period with a heavy labelling technique.
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Affiliation(s)
- Alessandro Foscari
- University of Trieste, Trieste, Italy
- Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Udine, Italy
| | - Giulia Leonarduzzi
- University of Trieste, Trieste, Italy
- Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Udine, Italy
| | - Guido Incerti
- Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Udine, Italy
- * E-mail:
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Araus JL, Rezzouk FZ, Thushar S, Shahid M, Elouafi IA, Bort J, Serret MD. Effect of irrigation salinity and ecotype on the growth, physiological indicators and seed yield and quality of Salicornia europaea. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 304:110819. [PMID: 33568309 DOI: 10.1016/j.plantsci.2021.110819] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/28/2020] [Accepted: 01/02/2021] [Indexed: 06/12/2023]
Abstract
The euhalophyte species Salicornia europaea is cultivated for oilseed and as a fodder crop in various parts of the world. In saline coastal environments it possesses great potential for the subsistence of the most disadvantaged farmers. We investigated the effect of salinity levels in irrigation water on the germination capacity, shoot biomass and seed productivity as well as diverse quality traits (nitrogen content in shoots and seeds and fatty acids, in seeds) and physiological traits (stable carbon and nitrogen isotopes and ion content) of two accessions collected in the United Arab Emirates (UAE). The three salinity levels tested were irrigation with fresh water (0.3 dS m-1), brackish water (25 dS m-1) and sea water (40 dS m-1). In addition, a hypersaline condition (80 dS m-1) was also tested for germination. The best germination rates were achieved with seeds exposed to fresh and brackish water, while imbibition with sea water decreased germination by half and hypersaline water inhibited it almost totally. However, the best irrigation regime in terms of biomass and seed yield involved brackish water. Moreover, rising salinity in the irrigation increased the stable isotope composition of carbon (δ13C) and nitrogen (δ15N), together with the Na+ and K+ of shoots and seeds, and the lipid levels of seeds, while the total nitrogen content and the profile of major fatty acids of seeds did not change. Differences between the two ecotypes existed for growth and seed yield with the best ecotype exhibiting lower δ13C and higher K+ in both shoots and seeds, lower Na+ and higher δ15N in shoots, and lower N in seeds, together with differences in major fatty acids. Physiological mechanisms behind the response to irrigation salinity and the ecotypic differences are discussed in terms of photosynthetic carbon and nitrogen metabolism.
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Affiliation(s)
- José L Araus
- Section of Plant Physiology, University of Barcelona, 08028 Barcelona, Spain; AGROTECNIO (Center of Research in Agrotechnology), 25198 Lleida, Spain.
| | - Fatima Zahra Rezzouk
- Section of Plant Physiology, University of Barcelona, 08028 Barcelona, Spain; AGROTECNIO (Center of Research in Agrotechnology), 25198 Lleida, Spain
| | - Sumitha Thushar
- International Center for Biosaline Agriculture (ICBA), P.O. Box 14660, Dubai, United Arab Emirates
| | - Mohammad Shahid
- International Center for Biosaline Agriculture (ICBA), P.O. Box 14660, Dubai, United Arab Emirates
| | - Ismahane A Elouafi
- International Center for Biosaline Agriculture (ICBA), P.O. Box 14660, Dubai, United Arab Emirates
| | - Jordi Bort
- Section of Plant Physiology, University of Barcelona, 08028 Barcelona, Spain; AGROTECNIO (Center of Research in Agrotechnology), 25198 Lleida, Spain
| | - Maria D Serret
- Section of Plant Physiology, University of Barcelona, 08028 Barcelona, Spain; AGROTECNIO (Center of Research in Agrotechnology), 25198 Lleida, Spain
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11
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Gauthier PPG, Saenz N, Griffin KL, Way D, Tcherkez G. Is the Kok effect a respiratory phenomenon? Metabolic insight using 13 C labeling in Helianthus annuus leaves. THE NEW PHYTOLOGIST 2020; 228:1243-1255. [PMID: 32564374 DOI: 10.1111/nph.16756] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 06/11/2020] [Indexed: 06/11/2023]
Abstract
The Kok effect is a well-known phenomenon in which the quantum yield of photosynthesis changes abruptly at low light. This effect has often been interpreted as a shift in leaf respiratory metabolism and thus used widely to measure day respiration. However, there is still no formal evidence that the Kok effect has a respiratory origin. Here, both gas exchange and isotopic labeling were carried out on sunflower leaves, using glucose that was 13 C-enriched at specific C-atom positions. Position-specific decarboxylation measurements and NMR analysis of metabolites were used to trace the fate of C-atoms in metabolism. Decarboxylation rates were significant at low light (including above the Kok break point) and increased with decreasing irradiance below 100 µmol photons m-2 s-1 . The variation in several metabolite pools such as malate, fumarate or citrate, and flux calculations suggest the involvement of several decarboxylating pathways in the Kok effect, including the malic enzyme. Our results show that day respiratory CO2 evolution plays an important role in the Kok effect. However, the increase in the apparent quantum yield of photosynthesis below the Kok break point is also probably related to malate metabolism, which participates in maintaining photosynthetic linear electron flow.
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Affiliation(s)
- Paul P G Gauthier
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
| | - Natalie Saenz
- Department of Chemistry, Columbia University, 3000 Broadway NYC, New York, NY, 10025, USA
| | - Kevin L Griffin
- Department of Ecology, Evolution and Environmental Biology (E3B), Columbia University, 1200 Amsterdam Avenue, New York, NY, 10027, USA
- Department of Earth and Environmental Sciences, Lamont Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY, 10964, USA
| | - Danielle Way
- Department of Biology, University of Western Ontario, 1151 Richmond Street, London, ON, N6A 5B7, Canada
- Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
- Nicholas School of the Environment, Duke University, Durham, NC, 27710, USA
| | - Guillaume Tcherkez
- Research School of Biology, Joint College of Sciences, Australian National University, Canberra, ACT, 2601, Australia
- Seedling Metabolism and Stress, Institut de Recherche en Horticulture et Semences, INRAE Angers, Université d'Angers, 42 rue Georges Morel, Beaucouzé Cedex, 49780, France
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Metabolic Responses to Waterlogging Differ between Roots and Shoots and Reflect Phloem Transport Alteration in Medicago truncatula. PLANTS 2020; 9:plants9101373. [PMID: 33076529 PMCID: PMC7650564 DOI: 10.3390/plants9101373] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/01/2020] [Accepted: 10/02/2020] [Indexed: 11/17/2022]
Abstract
Root oxygen deficiency that is induced by flooding (waterlogging) is a common situation in many agricultural areas, causing considerable loss in yield and productivity. Physiological and metabolic acclimation to hypoxia has mostly been studied on roots or whole seedlings under full submergence. The metabolic difference between shoots and roots during waterlogging, and how roots and shoots communicate in such a situation is much less known. In particular, the metabolic acclimation in shoots and how this, in turn, impacts on roots metabolism is not well documented. Here, we monitored changes in the metabolome of roots and shoots of barrel clover (Medicago truncatula), growth, and gas-exchange, and analyzed phloem sap exudate composition. Roots exhibited a typical response to hypoxia, such as γ-aminobutyrate and alanine accumulation, as well as a strong decline in raffinose, sucrose, hexoses, and pentoses. Leaves exhibited a strong increase in starch, sugars, sugar derivatives, and phenolics (tyrosine, tryptophan, phenylalanine, benzoate, ferulate), suggesting an inhibition of sugar export and their alternative utilization by aromatic compounds production via pentose phosphates and phosphoenolpyruvate. Accordingly, there was an enrichment in sugars and a decline in organic acids in phloem sap exudates under waterlogging. Mass-balance calculations further suggest an increased imbalance between loading by shoots and unloading by roots under waterlogging. Taken as a whole, our results are consistent with the inhibition of sugar import by waterlogged roots, leading to an increase in phloem sugar pool, which, in turn, exert negative feedback on sugar metabolism and utilization in shoots.
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Hu Y, Guy RD. Isotopic composition and concentration of total nitrogen and nitrate in xylem sap under near steady-state hydroponics. PLANT, CELL & ENVIRONMENT 2020; 43:2112-2123. [PMID: 32463123 DOI: 10.1111/pce.13809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 05/20/2020] [Accepted: 05/21/2020] [Indexed: 06/11/2023]
Abstract
After root uptake, nitrate is effluxed back to the medium, assimilated locally, or translocated to shoots. Rooted black cottonwood (Populus trichocarpa) scions were supplied with a NO3- -based (0.5 mM) nutrient medium of known isotopic composition (δ15 N), and xylem sap was collected by pressure bombing. To establish a sampling protocol, sap was collected from lower and upper stem sections at 0.1-0.2 MPa above the balancing pressure, and after increasing the pressure by a further 0.5 MPa. Xylem sap from upper stem sections was partially diluted at higher pressure. Further analysis was restricted to sap obtained from intact shoots at low pressure. Total-, NO3- -N and, by difference, organic-N concentrations ranged from 6.1-11.0, 1.2-2.4, and 4.6-9.4 mM, while discrimination relative to the nutrient medium was -6.3 to 0.5‰, -23.3 to -11.5‰ and - 1.3 to 4.9‰, respectively. There was diurnal variation in δ15 N of total- and organic-N, but not NO3- . The difference in δ15 N between xylem NO3- and organic-N suggests that discrimination by nitrate reductase is near 25.1 ± 1.6‰. When this value was used in an isotope mass balance model, the predicted xylem sap NO3- -N to total-N ratio closely matched direct measurement.
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Affiliation(s)
- Yi Hu
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Forest Sciences Centre, Vancouver, British Columbia, Canada
| | - Robert D Guy
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Forest Sciences Centre, Vancouver, British Columbia, Canada
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