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Li L, Zhou K, Yang X, Su X, Ding P, Zhu Y, Cao F, Han J. Leaf nitrogen allocation to non-photosynthetic apparatus reduces mesophyll conductance under combined drought-salt stress in Ginkgo biloba. FRONTIERS IN PLANT SCIENCE 2025; 16:1557412. [PMID: 40012733 PMCID: PMC11863189 DOI: 10.3389/fpls.2025.1557412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2025] [Accepted: 01/22/2025] [Indexed: 02/28/2025]
Abstract
Leaf nitrogen allocation plays a crucial role in determining both photosynthetic function and structural development of plants. However, the effects of drought, salt stress, and their combination on leaf nitrogen allocation, and how these affect mesophyll conductance (g m) and photosynthesis, remain poorly understood. In this study, we first investigated variations in photosynthetic characteristics and leaf nitrogen allocation, and analyzed the relationship between g m and leaf nitrogen allocation ratios in Ginkgo biloba under drought, salt and combined drought-salt stress. The results showed that all stress treatments significantly reduced the photosynthesis in G. biloba, with the combined drought-salt stress having the most significant inhibitory effect on the plant's physiological characteristics. Under combined drought-salt stress, the limitation of photosynthesis due to g m (MC L) was significantly greater than under individual drought or salt stress. In contrast, the limitation due to stomatal conductance (S L) was similar to that observed under drought but higher than under salt stress. No significant differences in biochemical limitations (B L) were found across all stress treatments. Further research suggests that the increase in MC L under combined drought-stress treatment may be linked to a greater allocation of leaf nitrogen to non-photosynthetic apparatus (e.g., cell structure) and a smaller allocation to photosynthetic enzymes (i.e., ribulose-1,5-bisphosphate carboxylase/oxygenase, Rubisco). This is supported by the positive correlation between g m and the proportion of nitrogen allocated to the carboxylation system (P r), as well as the negative correlation with the non-photosynthetic nitrogen ratio (P np). These findings help to advance our understanding of the mechanisms of photosynthesis and plant adaptability under combined drought-salt stress.
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Affiliation(s)
- Lehao Li
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Kai Zhou
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Xin Yang
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Xina Su
- Statistics, School of Mathematics and Statistics, Shandong University of Technology, Zibo, China
| | - Peng Ding
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Ying Zhu
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Fuliang Cao
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Jimei Han
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
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Haj-Yahya A, Sorek Y, Hochberg U, Ohana-Levi N, Zait Y, Shtein I. Bimodal pattern of allometric scaling along grapevine shoots. ANNALS OF BOTANY 2024; 134:1165-1176. [PMID: 39212300 PMCID: PMC11688528 DOI: 10.1093/aob/mcae146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Accepted: 08/29/2024] [Indexed: 09/04/2024]
Abstract
BACKGROUND AND AIMS Each branch internode, with the organs growing on it, can be seen as a single morphological phytomer subunit made of structurally and functionally interrelated components. However, allometric relationships between the anatomy and morphology of these subunits remain unclear, particularly in the axial context. The aim of this study was to address this knowledge gap by measuring morpho-anatomical parameters and their allometric relationships along grapevine shoots. METHODS To facilitate comparison, shoot length was normalized, and a relative position index was calculated for each internode, ranging from zero at the base to one at the apex. Scaling relationships between morpho-anatomical parameters along the axis were developed and validated by statistical modelling. KEY RESULTS Most morpho-anatomical parameters displayed an axial behaviour of increasing then decreasing in size from base to apex, with the exception of shoot diameter and shoot vessel density. A relative position index of 0.2 acted as the data turning point for most variables analysed. During the first phase (relative position index of <0.2), the traits of the phytomer organs are uncoupled and show weak allometric correlation, and during the second phase the traits exhibit strong allometric relationships. CONCLUSIONS Our findings suggest that allometric relationships along grapevine shoots are not constant; they exhibit a bimodal pattern, possibly influenced by seasonal temperatures. This work could aid in managing productivity shifts in agricultural and natural systems under global climate change and adds to basic knowledge of differentiation and development of growth units in plants.
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Affiliation(s)
| | - Yonatan Sorek
- Institute of Soil, Water and Environmental Science, Volcani Center, ARO, Rishon LeZion, Israel
| | - Uri Hochberg
- Institute of Soil, Water and Environmental Science, Volcani Center, ARO, Rishon LeZion, Israel
| | - Noa Ohana-Levi
- Independent Researcher, Variability, Ashalim 85512, Israel
| | - Yotam Zait
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Ilana Shtein
- Eastern Region R&D Center, Ariel, Israel
- Department of Molecular Biology, Ariel University, Ariel, Israel
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Shapira O, Hochberg U, Joseph A, McAdam S, Azoulay-Shemer T, Brodersen CR, Holbrook NM, Zait Y. Wind speed affects the rate and kinetics of stomatal conductance. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 120:1552-1562. [PMID: 39410670 DOI: 10.1111/tpj.17066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 07/19/2024] [Accepted: 09/20/2024] [Indexed: 11/19/2024]
Abstract
Understanding the relationship between wind speed and gas exchange in plants is a longstanding challenge. Our aim was to investigate the impact of wind speed on maximum rates of gas exchange and the kinetics of stomatal responses. We conducted experiments in different angiosperm and fern species using an infrared gas analyzer equipped with a controlled leaf fan, enabling precise control of the boundary layer conductance. We first showed that the chamber was adequately mixed even at extremely low wind speed (<0.005 m s-1) and evaluated the link between fan speed, wind speed, and boundary layer conductance. We observed that higher wind speeds led to increased gas exchange of both water vapor and CO₂, primarily due to the increase in boundary layer conductance. This increase in transpiration subsequently reduced epidermal pressure, leading to stomatal opening. We documented that stomatal opening in response to light was 2.5 times faster at a wind speed of 2 m s-1 compared to minimal wind speed in Vicia faba, while epidermal peels in a buffer with no transpiration exhibited a similar opening rate. The increase in stomatal conductance under high wind was also observed in four angiosperm species under field conditions, but it was not observed in Boston fern (Nephrolepis exaltata), which lacks epidermal mechanical advantage. Our findings highlight the significant impact of boundary layer conductance on determining gas exchange rates and the kinetics of gas exchange responses to environmental changes.
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Affiliation(s)
- Or Shapira
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Uri Hochberg
- Institute of Soil, Water and Environmental Sciences, Volcani Center, Agricultural Research Organization, Newe Ya'ar, Israel
| | - Ariel Joseph
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Scott McAdam
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Tamar Azoulay-Shemer
- Fruit Tree Sciences, Volcani Center, Agricultural Research Organization, Newe Ya'ar, Israel
| | - Craig R Brodersen
- School of the Environment, Yale University, New Haven, Connecticut, USA
| | - Noel Michelle Holbrook
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Yotam Zait
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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Hu W, Loka DA, Yang Y, Wu Z, Wang J, Liu L, Wang S, Zhou Z. Partial root-zone drying irrigation improves intrinsic water-use efficiency and maintains high photosynthesis by uncoupling stomatal and mesophyll conductance in cotton leaves. PLANT, CELL & ENVIRONMENT 2024; 47:3147-3165. [PMID: 38693776 DOI: 10.1111/pce.14932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 04/14/2024] [Accepted: 04/17/2024] [Indexed: 05/03/2024]
Abstract
Partial root-zone drying irrigation (PRD) can improve water-use efficiency (WUE) without reductions in photosynthesis; however, the mechanism by which this is attained is unclear. To amend that, PRD conditions were simulated by polyethylene glycol 6000 in a root-splitting system and the effects of PRD on cotton growth were studied. Results showed that PRD decreased stomatal conductance (gs) but increased mesophyll conductance (gm). Due to the contrasting effects on gs and gm, net photosynthetic rate (AN) remained unaffected, while the enhanced gm/gs ratio facilitated a larger intrinsic WUE. Further analyses indicated that PRD-induced reduction of gs was related to decreased stomatal size and stomatal pore area in adaxial and abaxial surface which was ascribed to lower pore length and width. PRD-induced variation of gm was ascribed to the reduced liquid-phase resistance, due to increases in chloroplast area facing to intercellular airspaces and the ratio of chloroplast surface area to total mesophyll cell area exposed to intercellular airspaces, as well as to decreases in the distance between cell wall and chloroplast, and between adjacent chloroplasts. The above results demonstrate that PRD, through alterations to stomatal and mesophyll structures, decoupled gs and gm responses, which ultimately increased intrinsic WUE and maintained AN.
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Affiliation(s)
- Wei Hu
- College of Agriculture, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Dimitra A Loka
- Institute of Industrial and Forage Crops, Hellenic Agricultural Organization, Larisa, Greece
| | - Yuanli Yang
- College of Agriculture, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Ziqing Wu
- College of Agriculture, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Jun Wang
- College of Agriculture, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Lin Liu
- College of Agriculture, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Shanshan Wang
- College of Agriculture, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Zhiguo Zhou
- College of Agriculture, Nanjing Agricultural University, Nanjing, People's Republic of China
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Arshad MJ, Khan MI, Ali MH, Farooq Q, Hussain MI, Seleiman MF, Asghar MA. Enhanced wheat productivity in saline soil through the combined application of poultry manure and beneficial microbes. BMC PLANT BIOLOGY 2024; 24:423. [PMID: 38760709 PMCID: PMC11102207 DOI: 10.1186/s12870-024-05137-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Accepted: 05/13/2024] [Indexed: 05/19/2024]
Abstract
BACKGROUND Soil salinity is one of the major menaces to food security, particularly in dealing with the food demand of the ever-increasing global population. Production of cereal crops such as wheat is severely affected by soil salinity and improper fertilization. The present study aimed to examine the effect of selected microbes and poultry manure (PM) on seedling emergence, physiology, nutrient uptake, and growth of wheat in saline soil. A pot experiment was carried out in research area of Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan. Saline soil (12 dS m- 1 w/w) was developed by spiking using sodium chloride, and used in experiment along with two microbial strains (i.e., Alcaligenes faecalis MH-2 and Achromobacter denitrificans MH-6) and PM. Finally, wheat seeds (variety Akbar-2019) were sown in amended and unamended soil, and pots were placed following a completely randomized design. The wheat crop was harvested after 140 days of sowing. RESULTS The results showed a 10-39% increase (compared to non-saline control) in agronomic, physiological, and nutritive attributes of wheat plants when augmented with PM and microbes. Microbes together with PM significantly enhanced seedling emergence (up to 38%), agronomic (up to 36%), and physiological (up to 33%) in saline soil as compared to their respective unamended control. Moreover, the co-use of microbes and PM also improved soil's physicochemical attributes and enhanced N (i.e., 21.7%-17.1%), P (i.e., 24.1-29.3%), and K (i.e., 28.7%-25.3%) availability to the plant (roots and shoots, respectively). Similarly, the co-use of amendments also lowered the Na+ contents in soil (i.e., up to 62%) as compared to unamended saline control. This is the first study reporting the effects of the co-addition of newly identified salt-tolerant bacterial strains and PM on seedling emergence, physiology, nutrient uptake, and growth of wheat in highly saline soil. CONCLUSION Our findings suggest that co-using a multi-trait bacterial culture and PM could be an appropriate option for sustainable crop production in salt-affected soil.
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Affiliation(s)
- Muhammad Junaid Arshad
- Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan
| | - Muhammad Imran Khan
- Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan.
- Department of Isotope Biogeochemistry, Helmholtz- Center for Environmental Research- UFZ, Leipzig, Germany.
| | - Muhammad Hayder Ali
- Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan
| | - Qammar Farooq
- Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan
| | | | - Mahmoud F Seleiman
- Department of Plant Production, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh, 11451, Saudi Arabia
| | - Muhammad Ahsan Asghar
- Department of Biological Resources, Agricultural Institute, Centre for Agricultural Research, ELKH, Brunzvik St, Martonvásár, 2462, Hungary
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Physiological Changes of Arabica Coffee under Different Intensities and Durations of Water Stress in the Brazilian Cerrado. PLANTS 2022; 11:plants11172198. [PMID: 36079581 PMCID: PMC9460576 DOI: 10.3390/plants11172198] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/10/2022] [Accepted: 08/11/2022] [Indexed: 11/17/2022]
Abstract
Coffee farmers have faced problems due to drought periods, with irrigation being necessary. In this sense, this study aimed to evaluate the responses to different levels and durations of water deficit in arabica coffee genotypes in the Cerrado region. The experiment consisted of three Coffea arabica genotypes and five water regimes: full irrigation (FI 100 and FI 50—full irrigation with 100% and 50% replacement of evapotranspiration, respectively), water deficit (WD 100 and WD 50—water deficit from June to September, with 100% and 50% replacement of evapotranspiration, respectively) and rainfed (without irrigation). The variables evaluated were gas exchange, relative water content (RWC) and productivity. The results showed that during stress, plants under the FI water regime showed higher gas exchange and RWC, differently from what occurred in the WD and rainfed treatments; however, after irrigation, coffee plants under WDs regained their photosynthetic potential. Rainfed and WD 50 plants had more than 50% reduction in RWC compared to FIs. The Iapar 59 cultivar was the most productive genotype and the E237 the lowest. Most importantly, under rainfed conditions, the plants showed lower physiological and productive potential, indicating the importance of irrigation in Coffea arabica in the Brazilian Cerrado.
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Keeley M, Rowland D, Vincent C. Citrus photosynthesis and morphology acclimate to phloem-affecting huanglongbing disease at the leaf and shoot levels. PHYSIOLOGIA PLANTARUM 2022; 174:e13662. [PMID: 35253914 DOI: 10.1111/ppl.13662] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 03/02/2022] [Accepted: 03/03/2022] [Indexed: 06/14/2023]
Abstract
Huanglongbing (HLB) is a phloem-affecting disease in citrus that reduces growth and impacts global citrus production. HLB is caused by a phloem-limited bacterium (Candidatus Liberibacter asiaticus). By inhibiting phloem function, HLB stunts sink growth, including the production of new shoots and leaves, and induces hyperaccumulation of foliar starch. HLB induces feedback inhibition of photosynthesis by reducing foliar carbohydrate export. Here, we assessed the relationship of bacterial distribution within the foliage, foliar starch accumulation, and net CO2 assimilation (Anet ). Because HLB impacts canopy morphology, we developed a chamber to measure whole-shoot Anet to test the effects of HLB at both the leaf and shoot level. Whole-shoot level Anet saturated at high irradiance, and green stems had high photosynthetic rates compared to leaves. Starch accumulation was correlated with bacterial population, and starch was negatively correlated with Anet at the leaf but not at the shoot level. Starch increased initially after infection, then decreased progressively with increasing length of infection. HLB infection reduced Anet at the leaf level but increased it at the whole-shoot level, in association with reduced leaf size and greater relative contribution of stems to the photosynthetic surface area. Although HLB-increased photosynthetic efficiency, total carbon fixed per shoot decreased because photosynthetic surface area was reduced. We conclude that the localized effects of infection on photosynthesis are mitigated by whole-shoot morphological acclimation over time. Stems contribute important proportions of whole-shoot Anet , and these contributions are likely increased by the morphological acclimation induced by HLB.
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Affiliation(s)
- Mark Keeley
- Agronomy Department, University of Florida, Gainesville, Florida, USA
| | - Diane Rowland
- Agronomy Department, University of Florida, Gainesville, Florida, USA
| | - Christopher Vincent
- Horticultural Sciences Department, Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, USA
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Zait Y, Ferrero‐Serrano Á, Assmann SM. The α subunit of the heterotrimeric G protein regulates mesophyll CO 2 conductance and drought tolerance in rice. THE NEW PHYTOLOGIST 2021; 232:2324-2338. [PMID: 34515342 PMCID: PMC9293471 DOI: 10.1111/nph.17730] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 09/01/2021] [Indexed: 05/03/2023]
Abstract
Mesophyll conductance gm determines CO2 diffusion rates from mesophyll intercellular air spaces to the chloroplasts and is an important factor limiting photosynthesis. Increasing gm in cultivated plants is a potential strategy to increase photosynthesis and intrinsic water use efficiency (WUEi ). The anatomy of the leaf and metabolic factors such as aquaporins and carbonic anhydrases have been identified as important determinants of gm . However, genes involved in the regulation and modulation of gm remain largely unknown. In this work, we investigated the role of heterotrimeric G proteins in gm and drought tolerance in rice d1 mutants, which harbor a null mutation in the Gα subunit gene, RGA1. d1 mutants in both cv Nipponbare and cv Taichung 65 exhibited increased gm , fostering improvement in photosynthesis, WUEi , and drought tolerance compared with wild-type. The increased surface area of mesophyll cells and chloroplasts exposed to intercellular airspaces and the reduced cell wall and chloroplast thickness in the d1 mutant are evident contributors to the increase in gm . Our results indicate that manipulation of heterotrimeric G protein signaling has the potential to improve crop WUEi and productivity under drought.
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Affiliation(s)
- Yotam Zait
- Biology DepartmentPenn State University208 Mueller LaboratoryUniversity ParkPA16802USA
| | - Ángel Ferrero‐Serrano
- Biology DepartmentPenn State University208 Mueller LaboratoryUniversity ParkPA16802USA
| | - Sarah M. Assmann
- Biology DepartmentPenn State University208 Mueller LaboratoryUniversity ParkPA16802USA
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Sterling A, Guaca-Cruz L, Clavijo-Arias EA, Rodríguez-Castillo N, Suárez JC. Photosynthesis-Related Responses of Colombian Elite Hevea brasiliensis Genotypes under Different Environmental Variations: Implications for New Germplasm Selection in the Amazon. PLANTS 2021; 10:plants10112320. [PMID: 34834685 PMCID: PMC8620879 DOI: 10.3390/plants10112320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/16/2021] [Accepted: 10/21/2021] [Indexed: 11/24/2022]
Abstract
The objective of this study was to evaluate photosynthetic performance based on gas exchange traits, chlorophyll a fluorescence, and leaf water potential (ΨL) in nine Hevea brasiliensis genotypes from the ECC-1 (Élite Caquetá Colombia) selection and the cultivar IAN 873 (control) in response to different climatic (semi-humid warm and humid warm climates), seasonal (dry and rainy periods), and hourly (3:00 to 18:00) variations that can generate stress in the early growth stage (two-year-old plants) in two large-scale clonal trials in the Colombian Amazon. The photosynthetic performance in 60% of the Colombian genotypes was slightly affected under the conditions with less water availability (dry period, semi-humid warm site, and between 9:00 and 15:00 h), as compared with IAN 873, whose affectation was moderate in terms of photosynthesis rates, but its water conservation strategy was strongly affected. The ECC 90, ECC 83, and ECC 73 genotypes had the best photosynthetic performance under conditions of greater water limitation, and ECC 35, and ECC 64 had a higher water status based on the leaf water potential, with intermediate photosynthetic performance. This germplasm has a high potential for selection in rubber tree breeding programs in future scenarios of climate change in the Colombian Amazon.
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Affiliation(s)
- Armando Sterling
- Phytopathology Laboratory, Faculty of Basis Sciences, Sinchi Amazonian Institute of Scientific Research, Universidad de la Amazonía, Florencia 180001, Caquetá, Colombia; (L.G.-C.); (E.A.C.-A.); (N.R.-C.)
- Correspondence: ; Tel.: +57-310-786-2496
| | - Lised Guaca-Cruz
- Phytopathology Laboratory, Faculty of Basis Sciences, Sinchi Amazonian Institute of Scientific Research, Universidad de la Amazonía, Florencia 180001, Caquetá, Colombia; (L.G.-C.); (E.A.C.-A.); (N.R.-C.)
- Natural Sciences and Sustainable Development, Faculty of Agricultural Sciences, Universidad de la Amazonía, Florencia 180001, Caquetá, Colombia
| | - Edwin Andrés Clavijo-Arias
- Phytopathology Laboratory, Faculty of Basis Sciences, Sinchi Amazonian Institute of Scientific Research, Universidad de la Amazonía, Florencia 180001, Caquetá, Colombia; (L.G.-C.); (E.A.C.-A.); (N.R.-C.)
| | - Natalia Rodríguez-Castillo
- Phytopathology Laboratory, Faculty of Basis Sciences, Sinchi Amazonian Institute of Scientific Research, Universidad de la Amazonía, Florencia 180001, Caquetá, Colombia; (L.G.-C.); (E.A.C.-A.); (N.R.-C.)
| | - Juan Carlos Suárez
- Ecophysiology Laboratory, Agroecological Engineering Program, Faculty of Engineering, Universidad de la Amazonia, Florencia 180001, Caquetá, Colombia;
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Shen ZJ, Qin YY, Luo MR, Li Z, Ma DN, Wang WH, Zheng HL. Proteome analysis reveals a systematic response of cold-acclimated seedlings of an exotic mangrove plant Sonneratia apetala to chilling stress. J Proteomics 2021; 248:104349. [PMID: 34411764 DOI: 10.1016/j.jprot.2021.104349] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/27/2021] [Accepted: 08/06/2021] [Indexed: 01/08/2023]
Abstract
Low temperature in winter was the most crucial abiotic stress that limits the mangrove afforestation northward. Previous study demonstrated that Sonneratia apetala initially transplanted to high latitude area exhibited a stronger plasticity of cold tolerance. To clarify the underlying mechanism, the physiological and proteomic responses to chilling stress were investigated in S. apetala leaves. Our results found that cold-acclimated seedlings had lower relative electrolyte leakage and MDA content than non-acclimated seedlings. On the contrary, higher chlorophyll content and photosynthetic capacity were observed in cold-acclimated seedlings. With proteomic analyses, the differentially accumulated proteins (DAPs) involved in ROS scavenging, photosynthesis and energy metabolism, carbohydrate metabolism, cofactor biosynthesis, and protein folding were suggested to play important roles in enhancing the cold tolerance of S. apetala. However, the down-regulation DAPs were suggested as a tradeoff between plant growth and chilling response. By the protein-protein interaction analyses, translation elongation factor G, chlorophyll A-B binding protein and ascorbate peroxidase 1 were suggested as the important regulators in cold-acclimated S. apetala seedlings under chilling stress. Based on the above results, a schematic diagram describing the mechanism of cold tolerance of exotic mangrove species S. apetala that was achieved by cold acclimation was presented in this study. SIGNIFICANCE: The major environmental factor limits the mangrove afforestation northward is the low temperature in winter. Previous study reported that Sonneratia apetala grew in high latitude exhibited a higher cold tolerance than that in low latitude, which was suggested as a result of cold acclimation. To further understand "how cold acclimation enhance the cold tolerance in S. apetala", the response of S. apetala subjected to chilling stress with or without cold acclimation was investigated in this study at the physiological and proteomic aspects. Our physiological results showed that S. apetala seedlings treated with cold acclimation exhibited a higher tolerance under chilling stress than that without cold acclimation. By using the comparative proteomic approaches and bioinformatic analyses, various biological processes were suggested to play an important role in enhancing the cold tolerance of S. apetala under chilling stress, such as ROS scavenging, photosynthesis and energy metabolism, carbohydrate metabolism, cofactor biosynthesis, and protein folding. Among these differentially accumulated proteins, translation elongation factor G (eEF-G), chlorophyll A-B binding protein (CAB) and ascorbate peroxidase 1 (APX1) were identified as the hub proteins function in coordinated regulating ROS scavenging, photosynthesis and protein biosynthesis in chloroplast and subsequently enhanced the cold tolerance of S. apetala under chilling stress. Our results provided a further understanding of cold acclimation in improving the cold tolerance in exotic mangrove species S. apetala.
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Affiliation(s)
- Zhi-Jun Shen
- Key Laboratory for Subtropical Wetland Ecosystem Research of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361005, PR China
| | - Ying-Ying Qin
- Key Laboratory for Subtropical Wetland Ecosystem Research of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361005, PR China; Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, College of Environment and Resources, Guangxi Normal University, Guilin, Guangxi 541004, PR China
| | - Mei-Rong Luo
- Key Laboratory for Subtropical Wetland Ecosystem Research of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361005, PR China
| | - Zan Li
- Key Laboratory for Subtropical Wetland Ecosystem Research of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361005, PR China
| | - Dong-Na Ma
- Key Laboratory for Subtropical Wetland Ecosystem Research of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361005, PR China
| | - Wen-Hua Wang
- Fujian Key Laboratory of Subtropical Plant Physiology and Biochemistry, Fujian Institute of Subtropical Botany, Xiamen, Fujian 361006, PR China
| | - Hai-Lei Zheng
- Key Laboratory for Subtropical Wetland Ecosystem Research of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361005, PR China.
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Liu M, Liu X, Du X, Korpelainen H, Niinemets Ü, Li C. Anatomical variation of mesophyll conductance due to salt stress in Populus cathayana females and males growing under different inorganic nitrogen sources. TREE PHYSIOLOGY 2021; 41:1462-1478. [PMID: 33554242 DOI: 10.1093/treephys/tpab017] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 01/18/2021] [Indexed: 05/26/2023]
Abstract
Synergistic regulation in leaf architecture and photosynthesis is essential for salt tolerance. However, how plant sex and inorganic nitrogen sources alter salt stress-dependent photosynthesis remains unknown. Leaf anatomical characteristics and photosynthesis of Populus cathayana Rehder females and males were investigated under salt stress conditions combined with nitrate NO3- and ammonium NH4+ supplies to clarify the underlying mechanisms. In salt-stressed females, we observed an increased mesophyll spongy cell density, a reduced chloroplast density, a decreased surface area of chloroplasts adjacent to the intercellular air space (Sc/S) and an increased mesophyll cell area per transverse section width (S/W), consequently causing mesophyll conductance (gm) and photosynthesis inhibition, especially under NH4+ supply. Conversely, males with a greater mesophyll palisade tissue thickness and chloroplast density, but a lower spongy cell density had lower S/W and higher Sc/S, and higher gm and photosynthesis. NH4+-fed females had a lower CO2 conductance through cell wall and stromal conductance perpendicular to the cell wall, but a higher chloroplast conductance from the cell wall (gcyt1) than females supplied with NO3-, whereas males had a higher chloroplast conductance and lower CO2 conductance through cell wall when supplied with NO3- instead of NH4+ under salt stress. These findings indicate sex-specific strategies in coping with salt stress related to leaf anatomy and gm under both types of nitrogen supplies, which may contribute to sex-specific CO2 capture and niche segregation.
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Affiliation(s)
- Miao Liu
- College of Life and Environmental Sciences, Hangzhou Normal University, Yuhangtang Road 2318, Hangzhou 311121, China
| | - Xiucheng Liu
- College of Life and Environmental Sciences, Hangzhou Normal University, Yuhangtang Road 2318, Hangzhou 311121, China
| | - Xuhua Du
- Key Laboratory of State Forestry and Grassland Administration on Bamboo Resources and Utilization, China National Bamboo Research Center, State Forestry and Grassland Administration, Wenyi Road 310, Hangzhou 310012, China
| | - Helena Korpelainen
- Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, PO P.O. Box 27, Latokartanonkaari 5, FI-00014 Helsinki, Finland
| | - Ülo Niinemets
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, 51006 Tartu, Estonia
- Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn, Estonia
| | - Chunyang Li
- College of Life and Environmental Sciences, Hangzhou Normal University, Yuhangtang Road 2318, Hangzhou 311121, China
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12
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Shtein I, Wolberg S, Munitz S, Zait Y, Rosenzweig T, Grünzweig JM, Ohana-Levi N, Netzer Y. Multi-seasonal water-stress memory versus temperature-driven dynamic structural changes in grapevine. TREE PHYSIOLOGY 2021; 41:1199-1211. [PMID: 33416079 DOI: 10.1093/treephys/tpaa181] [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: 08/18/2020] [Accepted: 12/24/2020] [Indexed: 06/12/2023]
Abstract
Perennial plants perpetually adapt to environmental changes in complex and yet insufficiently understood manner. We aimed to separate the intra-seasonal temperature effects on structure and function from perennial and annual water stress effects. This study focused on grapevine (Vitis vinifera L. 'Cabernet Sauvignon') petioles, which being a continuously produced organ, represent the current status of the plant. Field-grown mature plants subjected to multi-annual irrigation treatments (severe water stress, mild water stress and non-stressed) throughout the growing season were compared with greenhouse-grown plants under three temperature regimes (22, 28 and 34 °C). Physiological and functional anatomy parameters were measured. A generalized additive model (GAM) based on meteorological and lysimeter-based field data was applied to determine the relative influence of various meteorological parameters on evapotranspiration (ETc) during the growing season in the field experiment. At the beginning of the growing season, in May, petioles in the severe stress treatment showed a stress-related structure (decreased length, safer hydraulic structure and increased lignification), though having high values of stem water potential (SWP). As the season progressed and temperatures increased, all water availability treatments petioles showed similar changes, and at the end of season, in August, were structurally very similar. Those changes were independent of SWP and were comparable to high temperature-induced changes in the greenhouse. In contrast, stems hydraulic structure was strongly influenced by water availability. Regression analyses indicated a relationship between petioles xylem structure and stomatal conductance (gs), whereas gs (but not SWP) was temperature-dependent. The GAM showed that ETc was mainly dependent on temperature. Our results indicate a perennial water-stress memory response, influencing the petiole structure at the beginning of the following season. Intra-seasonally, the petiole's structure becomes independent of water status, whereas temperature drives the structural changes. Thus, ongoing climate change might disrupt plant performance by purely temperature-induced effects.
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Affiliation(s)
- Ilana Shtein
- Department of Agriculture and Oenology, Eastern Region Research and Development Center, Ariel 40700, Israel
| | - Shunamit Wolberg
- Department of Agriculture and Oenology, Eastern Region Research and Development Center, Ariel 40700, Israel
- The Department of Molecular Biology, Ariel University, Ariel 40700, Israel
| | | | - Yotam Zait
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Tovit Rosenzweig
- The Department of Molecular Biology, Ariel University, Ariel 40700, Israel
| | - José M Grünzweig
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | | | - Yishai Netzer
- Department of Agriculture and Oenology, Eastern Region Research and Development Center, Ariel 40700, Israel
- Department of Chemistry & Biotech Engineering, Ariel University, Ariel 40700, Israel
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13
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Wu J, Shi Z, Liu S, Centritto M, Cao X, Zhang M, Zhao G. Photosynthetic capacity of male and female Hippophae rhamnoides plants along an elevation gradient in eastern Qinghai-Tibetan Plateau, China. TREE PHYSIOLOGY 2021; 41:76-88. [PMID: 32785643 DOI: 10.1093/treephys/tpaa105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/10/2020] [Indexed: 06/11/2023]
Abstract
Elevational variations in the growing environment and sex differences in individuals drive the diversification of photosynthetic capacity of plants. However, photosynthetic response of dioecious plants to elevation gradients and the mechanisms that cause these responses are poorly understood. We measured foliar gas exchange, chlorophyll fluorescence and nitrogen allocations of male and female Seabuckthorn (Hippophae rhamnoides L.) at the elevation of 1900-3700 m above sea level (a.s.l.) on the eastern Qinghai-Tibetan Plateau, China. Male and female plants showed increased leaf photosynthetic capacity at higher elevation generally with no sex-specific difference. Photosynthetic photon flux density-saturated photosynthesis (Asat) was limited mostly by diffusional components (77 ± 1%), whereas biochemical components contributed minor limitations (22 ± 1%). Mesophyll conductance (gm) played an essential role in Asat variation, accounting for 40 ± 2% of the total photosynthetic limitations and had a significant positive correlation with Asat. Leaf nitrogen allocations to Rubisco (PR) and bioenergetics (PB) in the photosynthetic apparatus were major drivers for variations in photosynthetic nitrogen-use efficiency. The increase of these resource uptake capacities enables H. rhamnoides to maintain a high level of carbon assimilation and function efficiently to cope with the harsh conditions and shorter growing season at higher elevation.
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Affiliation(s)
- Jiamei Wu
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China
| | - Zuomin Shi
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China
- Institute for Sustainable Plant Protection, National Research Council of Italy, Torino 10135, Italy
| | - Shun Liu
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China
| | - Mauro Centritto
- Institute for Sustainable Plant Protection, National Research Council of Italy, Torino 10135, Italy
| | - Xiangwen Cao
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China
| | - Miaomiao Zhang
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China
| | - Guangdong Zhao
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China
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14
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Zait Y, Konsens I, Schwartz A. Elucidating the limiting factors for regeneration and successful establishment of the thermophilic tree Ziziphus spina-christi under a changing climate. Sci Rep 2020; 10:14335. [PMID: 32868849 PMCID: PMC7459324 DOI: 10.1038/s41598-020-71276-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 08/04/2020] [Indexed: 11/26/2022] Open
Abstract
Due to climate change, winter temperatures are predicted to increase worldwide. For thermophilic trees, highly sensitive to low temperatures, an increase in winter temperatures may be beneficial for survival and regeneration. Ziziphus spina-christi is a thermophilic tree that has recently become more abundant and widespread in the eastern Mediterranean, presumably due to a gradual increase in winter temperatures. We aim to define the temperature limitations for seed germination and the growth and survival of young seedlings to broaden our understanding of the future geographical distribution of this species. We studied effects of temperature on germination, growth, and photosynthesis in a controlled environment with four different day/night temperature regimes (34/28 °C, 28/22 °C, 22/16 °C and 16/10 °C). Effects of endocarp on germination and seed germination in the field were also studied. Results showed that germination has a lower thermal optimum (34–22 °C, 63.5–67.5% germination) than growth and photosynthesis (34–28 °C). Moderate cold stress (22/16 °C), did not affect germination capacity, but strongly reduced seedling growth (71%) and photosynthetic capacity (44.6%). Under severe cold stress (16/10 °C), germination still occurs (22%), but seedlings cannot perform growth and photosynthesis. We conclude that slow seedling growth, not germination, is the main barrier for successful establishment of Z. spina-christi under low temperature. Warmer winters could lead to earlier establishment of seedlings and increase their chance of survival the following summer. This may explain the recent increase in the tree’s relative abundance and further highlight the potential spread of this species at higher altitudes and latitudes across the Mediterranean.
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Affiliation(s)
- Yotam Zait
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
| | - Irit Konsens
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Amnon Schwartz
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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15
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Yang Y, Zhang Q, Huang G, Peng S, Li Y. Temperature responses of photosynthesis and leaf hydraulic conductance in rice and wheat. PLANT, CELL & ENVIRONMENT 2020; 43:1437-1451. [PMID: 32073150 DOI: 10.1111/pce.13743] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 02/12/2020] [Indexed: 06/10/2023]
Abstract
Studies on the temperature (T) responses of photosynthesis and leaf hydraulic conductance (Kleaf ) are important to plant gas exchange. In this study, the temperature responses of photosynthesis and Kleaf were studied in Shanyou 63 (Oryza sativa) and Yannong 19 (Triticum aestivum). Leaf water potential (Ψleaf ) was insensitive to T in Shanyou 63, while it significantly decreased with T in Yannong 19. The differential Ψleaf - T relationship partially accounted for the differing gm -T relationships, where gm was less sensitive to T in Yannong 19 than in Shanyou 63. With different gm -T and Ψleaf -T relationships, the temperature responses of photosynthetic limitations were surprisingly similar between the two lines, and the photosynthetic rate was highly correlated with gm . With the increasing T, Kleaf increased in Shanyou 63 while it decreased in Yannong 19. The different Kleaf -T relationships were related to different Ψleaf -T relationships. When excluding the effects of water viscosity and Ψleaf , Kleaf was insensitive to T in both lines. gm and Kleaf were generally not coordinated across different temperatures. This study highlights the importance of Ψleaf on leaf carbon and water exchanges, and the mechanisms for the gm -T and Kleaf -T relationships were discussed.
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Affiliation(s)
- Yuhan Yang
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Qiangqiang Zhang
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Guanjun Huang
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Shaobing Peng
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Yong Li
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
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16
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Mesophyll conductance: the leaf corridors for photosynthesis. Biochem Soc Trans 2020; 48:429-439. [DOI: 10.1042/bst20190312] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 01/25/2020] [Accepted: 01/30/2020] [Indexed: 12/15/2022]
Abstract
Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.
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17
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Sperlich D, Chang CT, Peñuelas J, Sabaté S. Responses of photosynthesis and component processes to drought and temperature stress: are Mediterranean trees fit for climate change? TREE PHYSIOLOGY 2019; 39:1783-1805. [PMID: 31553458 DOI: 10.1093/treephys/tpz089] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/19/2019] [Accepted: 08/15/2019] [Indexed: 05/24/2023]
Abstract
Global warming is raising concerns about the acclimatory capacity of trees and forests, especially in Mediterranean-type ecosystems. The sensitivity of photosynthesis to temperature is a key uncertainty for projecting the magnitude of terrestrial feedbacks on future climate change. While boreal, temperate and tropical species have been comparatively well investigated, our study provides the first comprehensive overview of the seasonal acclimatory responses of photosynthesis and its component processes to temperature in four Mediterranean climax species under natural conditions. We quantified seasonal changes in the responses of net photosynthesis (Anet), stomatal conductance (gs), mesophyllic conductance (gm) and electron-transport rate (Jcf), and investigated their sensitivity to drought and temperature stress in sunlit and shaded leaves of four Mediterranean tree species (Quercus ilex L., Pinus halepensis Mill., Arbutus unedo L. and Quercus pubescens Willd.). Sunlit leaves, but not shaded leaves, showed a pronounced seasonality in the temperature responses of Anet, gs, gm and Jcf. All four species and variables showed a remarkably dynamic and consistent acclimation of the thermal optimum (Topt), reaching peaks in summer ~29-32 °C. Changes in the shape of the response curves were, however, highly species-specific. Under severe drought, Topt of all variables were on average 22-29% lower. This was accompanied by narrower response curves above all in P. halepensis, reducing the optimal range for photosynthesis to the cooler morning or evening periods. Wider temperature-response curves and less strict stomatal control under severe drought were accompanied by wilting and drought-induced leaf shedding in Q. ilex and Q. pubescens and by additional branch dieback in A. unedo. Mild winter conditions led to a high Topt (~19.1-22.2 °C), benefitting the evergreen species, especially P. halepensis. Seasonal acclimation of Anet was explained better by gs and gm being less pronounced in Jcf. Drought was thus a key factor, in addition to growth temperature, to explain seasonal acclimation of photosynthesis. Severe drought periods may exceed more frequently the high acclimatory capacity of Mediterranean trees to high ambient temperatures, which could lead to reduced growth, increased leaf shedding and, for some species such as A. unedo, increased mortality risk.
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Affiliation(s)
- D Sperlich
- Chair of Forestry Economics and Forest Planning, Faculty of Environment and Natural Resources, University of Freiburg, 79085 Freiburg im Breisgau, Tennenbacherstr. 4, Germany
| | - C T Chang
- Department of Evolutionary Biology, Ecology and Environmental Sciences (BEECA), University of Barcelona (UB), Av. Diagonal 643, 08028 Barcelona
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain
| | - J Peñuelas
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain
- Global Ecology Unit CREAF-CSIC-UAB, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain
| | - S Sabaté
- Department of Evolutionary Biology, Ecology and Environmental Sciences (BEECA), University of Barcelona (UB), Av. Diagonal 643, 08028 Barcelona
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain
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