scholarly journals Responses of isoprene emission and photochemical efficiency to severe drought combined with prolonged hot weather in hybrid Populus

2020 ◽  
Vol 71 (22) ◽  
pp. 7364-7381
Author(s):  
Zhihong Sun ◽  
Yan Shen ◽  
Ülo Niinemets
Keyword(s):  
Emission Rate ◽  
Photochemical Efficiency ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Characteristics ◽  
Antioxidant Enzyme Activities ◽  
Severe Drought ◽  
Effective Quantum Yield ◽  
Isoprene Emission ◽  
Hot Weather

Abstract Isoprene emissions have been considered as a protective response of plants to heat stress, but there is limited information of how prolonged heat spells affect isoprene emission capacity, particularly under the drought conditions that often accompany hot weather. Under combined long-term stresses, presence of isoprene emission could contribute to the maintenance of the precursor pool for rapid synthesis of essential isoprenoids to repair damaged components of leaf photosynthetic apparatus. We studied changes in leaf isoprene emission rate, photosynthetic characteristics, and antioxidant enzyme activities in two hybrid Populus clones, Nanlin 1388 (relatively high drought tolerance) and Nanlin 895 (relatively high thermotolerance) that were subjected to long-term (30 d) soil water stress (25% versus 90% soil field capacity) combined with a natural heat spell (day-time temperatures of 35–40 °C) that affected both control and water-stressed plants. Unexpectedly, isoprene emissions from both the clones were similar and the overall effects of drought on the emission characteristics were initially minor; however, treatment effects and clonal differences increased with time. In particular, the isoprene emission rate only increased slightly in the Nanlin 895 control plants after 15 d of treatment, whereas it decreased by more than 5-fold in all treatment × clone combinations after 30 d. The reduction in isoprene emission rate was associated with a decrease in the pool size of the isoprene precursor dimethylallyl diphosphate in all cases at 30 d after the start of treatment. Net assimilation rate, stomatal conductance, the openness of PSII centers, and the effective quantum yield all decreased, and non-photochemical quenching and catalase activity increased in both control and water-stressed plants. Contrary to the hypothesis of protection of leaf photosynthetic apparatus by isoprene, the data collectively indicated that prolonged stress affected isoprene emissions more strongly than leaf photosynthetic characteristics. This primarily reflected the depletion of isoprene precursor pools under long-term severe stress.

scholarly journals Metabolic Responses of Hybrid Bermudagrass to Short-term and Long-term Drought Stress

2012 ◽  
Vol 137 (6) ◽  
pp. 411-420 ◽  
Author(s):  
Hongmei Du ◽  
Zhaolong Wang ◽  
Wenjuan Yu ◽  
Bingru Huang
Keyword(s):  
Drought Stress ◽  
Malic Acid ◽  
Photochemical Efficiency ◽  
Nitrogen Compound ◽  
Mass Spectrometry Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Grass Species ◽  
Severe Drought ◽  
Short Term

The accumulation of different types of metabolites may reflect variations in plant adaptation to different severities or durations of drought stress. The objectives of this project are to examine changes in metabolomic profiles and determine predominant metabolites in response to short-term (6 days) and long-term (18 days) drought stress with gas chromatography–mass spectrometry analysis in a C4 perennial grass species. Plants of hybrid bermudagrass (Cynodon dactylon × C. transvaalensis cv. Tifdwarf) were unirrigated for 18 days to induce drought stress in growth chambers. Physiological responses to drought stress were evaluated by visual rating of grass quality, relative water content, photochemical efficiency, and electrolyte leakage (EL). All parameters decreased significantly at 6 and 18 days of drought stress, except EL, which increased with the duration of drought stress. Under short-term drought stress (6 days), the content did not change significantly for most metabolites, except methionine, serine, γ-aminobutyric acid (GABA), isoleucine, and mannose. Most metabolites showed higher accumulation under long-term drought stress compared with that under the well-watered conditions, including three organic acids (malic acid, galacturonic acid, and succinic acid), 10 amino acids (proline, asparagine, phenylalanine, methionine, serine, 5-hydroxynorvaline, GABA, glycine, theorine, valine), seven sugars (sucrose, glucose, galactose, fructose, mannose, maltose, xylose), one nitrogen compound (ethanolamine), and two-sugar alcohol (myo-inositol). The accumulation of those metabolites, especially malic acid, proline, and sucrose, could be associated with drought adaptation of C4 hybrid bermudagrass to long-term or severe drought stress.

Altitudinal Variation in the Photosynthetic Characteristics of Snow Gum, Eucalyptus pauciflora Sieb. Ex Spreng. I. Seasonal Changes Under Field Conditions in the Snowy Mountains Area of South-Eastern Australia

1977 ◽  
Vol 25 (1) ◽  
pp. 1 ◽  
Author(s):  
RO Slayter ◽  
PA Morrow
Keyword(s):  
Seasonal Changes ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Characteristics ◽  
Maximum Temperature ◽  
Seasonal Temperature ◽  
South Eastern ◽  
Eastern Australia ◽  
Significant Difference ◽  
South Eastern Australia

A field study of seasonal changes in the photosynthetic characteristics of three altitudinal populations of the snow gum (Eucalyptus pauciflora Sieb. ex. Spreng) was conducted at elevations of 915, 1215 and 1645 m in the Snowy Mountains area of south-eastern Australia. At optimal temperatures in midsummer, peak rates of photosynthesis under CO2-saturating conditions (Psub) reached levels of 125-135 ng cm-2 sec-1, and under ambient CO2 conditions (Pamb) reached levels of 45-55 ng cm-2 sec-1. Corresponding values of the intracellular resistance to CO2 transfer (ri) were 5-6 sec cm-1, and of the gas phase resistance to water-vapour transfer (r,) 1.2-2 sec cm-1. Measured at temperatures of 15, 20 and 25°C, the peak seasonal values of Pmax showed no significant difference between sites, but at 5° and 10° peak values were highest at the highest elevation (coldest site), and at 30° and 35° peak values were highest at the lowest elevation (warmest site). Generally similar patterns applied to Paamb. These features are consistent with the view that E. Pauciflora shows continuous variation in many physiological characteristics over its altitudinal range. At each site the temperature optimum for photosynthesis changed markedly during the season, and was closely correlated both with the long-term maximum air temperature and with the mean maximum temperature of the 10 days prior to the date of measurement. This appeared to reflect long-term adaptation of the photosynthetic apparatus of each population to the general temperature conditions at each site, combined with a short-term acclimation to the prevailing seasonal temperature regime.

scholarly journals Impact of Drought and Salinity on Sweetgum Tree (Liquidambar styraciflua L.): Understanding Tree Ecophysiological Responses in the Urban Context

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 1032
Author(s):  
Rita Baraldi ◽  
Arkadiusz Przybysz ◽  
Osvaldo Facini ◽  
Lorenzo Pierdonà ◽  
Giulia Carriero ◽  
...  
Keyword(s):  
Salt Stress ◽  
Stomatal Conductance ◽  
Xanthophyll Cycle ◽  
Photochemical Efficiency ◽  
Photosynthetic Apparatus ◽  
Liquidambar Styraciflua ◽  
Photosynthetic Parameters ◽  
Urban Tree ◽  
Isoprene Emission ◽  
The Impact

Understanding urban tree responses to drought, salt stress, and co-occurring stresses, as well as the capability to recover afterward, is important to prevent the cited stresses’ negative effects on tree performance and ecological functionality. We investigated the impact of drought and salinity, alone and in combination, on leaf water potential, gas exchange, chlorophyll a fluorescence, xanthophyll cycle pigments, and isoprene emission of the urban tree species Liquidambar styraciflua L. Generally, drought had a rapid negative impact, while the effect of salt stress was more long lasting. Both stressors significantly decreased photosynthesis, transpiration, and stomatal conductance, as well as the maximum quantum efficiency of photosystem II (Fv/Fm) and the photochemical efficiency of PSII (ΦPSII), but increased nonphotochemical quenching (NPQ). Under stress conditions, a strong negative correlation between the PSII efficiency and the xanthophyll cycle pigment composition indicated a nocturnal retention of zeaxanthin and antheraxanthin in a state primed for energy dissipation. Drought and salt stress inhibited isoprene emission from leaves, although its emission was less responsive to stresses than stomatal conductance and photosynthesis. Full recovery of photosynthetic parameters took place after rewatering and washing off of excess salt, indicating that no permanent damage occurred, and suggesting downregulation rather than permanent impairment of the photosynthetic apparatus. Sweetgum trees were capable of withstanding and surviving moderate drought and salt events by activating defense mechanisms conferring tolerance to environmental stresses, without increasing the emission in the atmosphere of the highly reactive isoprene.

scholarly journals Exogenously Used 24-Epibrassinolide Promotes Drought Tolerance in Maize Hybrids by Improving Plant and Water Productivity in an Arid Environment

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 354
Author(s):  
El-Sayed M. Desoky ◽  
Elsayed Mansour ◽  
Mohamed M. A. Ali ◽  
Mohamed A. T. Yasin ◽  
Mohamed I. E. Abdul-Hamid ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Agronomic Traits ◽  
Water Productivity ◽  
Positive Association ◽  
Net Photosynthesis ◽  
Antioxidant Enzyme Activities ◽  
Severe Drought ◽  
Arid Environments ◽  
Maize Hybrids ◽  
Semi Arid

The influence of 24-epibrassinolide (EBR24), applied to leaves at a concentration of 5 μM, on plant physio-biochemistry and its reflection on crop water productivity (CWP) and other agronomic traits of six maize hybrids was field-evaluated under semi-arid conditions. Two levels of irrigation water deficiency (IWD) (moderate and severe droughts; 6000 and 3000 m3 water ha−1, respectively) were applied versus a control (well-watering; 9000 m3 water ha−1). IWD reduced the relative water content, membrane stability index, photosynthetic efficiency, stomatal conductance, and rates of transpiration and net photosynthesis. Conversely, antioxidant enzyme activities and osmolyte contents were significantly increased as a result of the increased malondialdehyde content and electrolyte leakage compared to the control. These negative influences of IWD led to a reduction in CWP and grain yield-related traits. However, EBR24 detoxified the IWD stress effects and enhanced all the above-mentioned parameters. The evaluated hybrids varied in drought tolerance; Giza-168 was the best under moderate drought, while Fine-276 was the best under severe drought. Under IWD, certain physiological traits exhibited a highly positive association with yield and yield-contributing traits or CWP. Thus, exogenously using EBR24 for these hybrids could be an effective approach to improve plant and water productivity under reduced available water in semi-arid environments.

scholarly journals Compensation Mechanism of the Photosynthetic Apparatus in Arabidopsis thaliana ch1 Mutants

2020 ◽  
Vol 22 (1) ◽  
pp. 221
Author(s):  
Joanna Wójtowicz ◽  
Adam K. Jagielski ◽  
Agnieszka Mostowska ◽  
Katarzyna B. Gieczewska
Keyword(s):  
Light Stress ◽  
Photosynthetic Apparatus ◽  
Protein Composition ◽  
Mrna Levels ◽  
Chlorophyll B ◽  
Low Light ◽  
Plant Acclimation ◽  
Chlorophyll B Deficiency ◽  
Composition Changes

The origin of chlorophyll b deficiency is a mutation (ch1) in chlorophyllide a oxygenase (CAO), the enzyme responsible for Chl b synthesis. Regulation of Chl b synthesis is essential for understanding the mechanism of plant acclimation to various conditions. Therefore, the main aim of this study was to find the strategy in plants for compensation of low chlorophyll content by characterizing and comparing the performance and spectral properties of the photosynthetic apparatus related to the lipid and protein composition in four selected Arabidopsis ch1 mutants and two Arabidopsis ecotypes. Mutation in different loci of the CAO gene, viz., NW41, ch1.1, ch1.2 and ch1.3, manifested itself in a distinct chlorina phenotype, pigment and photosynthetic protein composition. Changes in the CAO mRNA levels and chlorophyllide a (Chlide a) content in ecotypes and ch1 mutants indicated their significant role in the adjustment mechanism of the photosynthetic apparatus to low-light conditions. Exposure of mutants with a lower chlorophyll b content to short-term (1LL) and long-term low-light stress (10LL) enabled showing a shift in the structure of the PSI and PSII complexes via spectral analysis and the thylakoid composition studies. We demonstrated that both ecotypes, Col-1 and Ler-0, reacted to high-light (HL) conditions in a way remarkably resembling the response of ch1 mutants to normal (NL) conditions. We also presented possible ways of regulating the conversion of chlorophyll a to b depending on the type of light stress conditions.

scholarly journals Development and Verification of the Available Number of Water Intake Days in Ungauged Local Water Source Using the SWAT Model and Flow Recession Curves

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1511
Author(s):  
Jung-Ryel Choi ◽  
Il-Moon Chung ◽  
Se-Jin Jeung ◽  
Kyung-Su Choo ◽  
Cheong-Hyeon Oh ◽  
...  
Keyword(s):  
Water Supply ◽  
Water Intake ◽  
Water Resource Management ◽  
Assessment Tool ◽  
Swat Model ◽  
High Water ◽  
Coefficient Of Determination ◽  
Severe Drought ◽  
Regional Government

Climate change significantly affects water supply availability due to changes in the magnitude and seasonality of runoff and severe drought events. In the case of Korea, despite high water supply ratio, more populations have continued to suffer from restricted regional water supplies. Though Korea enacted the Long-Term Comprehensive Water Resources Plan, a field survey revealed that the regional government organizations limitedly utilized their drought-related data. These limitations present a need for a system that provides a more intuitive drought review, enabling a more prompt response. Thus, this study presents a rating curve for the available number of water intake days per flow, and reviews and calibrates the Soil and Water Assessment Tool (SWAT) model mediators, and found that the coefficient of determination, Nash–Sutcliffe efficiency (NSE), and percent bias (PBIAS) from 2007 to 2011 were at 0.92, 0.84, and 7.2%, respectively, which were “very good” levels. The flow recession curve was proposed after calculating the daily long-term flow and extracted the flow recession trends during days without precipitation. In addition, the SWAT model’s flow data enables the quantitative evaluations of the number of available water intake days without precipitation because of the high hit rate when comparing the available number of water intake days with the limited water supply period near the study watershed. Thus, this study can improve drought response and water resource management plans.

scholarly journals Photosynthesis and Related Physiological Parameters Differences Affected the Isoprene Emission Rate among 10 Typical Tree Species in Subtropical Metropolises

2021 ◽  
Vol 18 (3) ◽  
pp. 954
Author(s):  
Junyao Lyu ◽  
Feng Xiong ◽  
Ningxiao Sun ◽  
Yiheng Li ◽  
Chunjiang Liu ◽  
...  
Keyword(s):  
Photosynthetic Rate ◽  
Tree Species ◽  
Urban Areas ◽  
Emission Rate ◽  
Intercellular Co2 Concentration ◽  
Co2 Concentration ◽  
Single Species ◽  
Photosynthetic Parameters ◽  
Emission Rates ◽  
Isoprene Emission

Volatile organic compound (VOCs) emission is an important cause of photochemical smog and particulate pollution in urban areas, and urban vegetation has been presented as an important source. Different tree species have different emission levels, so adjusting greening species collocation is an effective way to control biogenic VOC pollution. However, there is a lack of measurements of tree species emission in subtropical metropolises, and the factors influencing the species-specific differences need to be further clarified. This study applied an in situ method to investigate the isoprene emission rates of 10 typical tree species in subtropical metropolises. Photosynthesis and related parameters including photosynthetic rate, intercellular CO2 concentration, stomatal conductance, and transpiration rate, which can influence the emission rate of a single species, were also measured. Results showed Salix babylonica always exhibited a high emission level, whereas Elaeocarpus decipiens and Ligustrum lucidum maintained a low level throughout the year. Differences in photosynthetic rate and stomatal CO2 conductance are the key parameters related to isoprene emission among different plants. Through the establishment of emission inventory and determination of key photosynthetic parameters, the results provide a reference for the selection of urban greening species, as well as seasonal pollution control, and help to alleviate VOC pollution caused by urban forests.

scholarly journals Influence of High Temperature on Photosynthesis, Antioxidative Capacity of Chloroplast, and Carbon Assimilation among Heat-tolerant and Heat-susceptible Genotypes of Nonheading Chinese Cabbage

HortScience ◽  
2017 ◽  
Vol 52 (11) ◽  
pp. 1464-1470 ◽  
Author(s):  
Lingyun Yuan ◽  
Yujie Yuan ◽  
Shan Liu ◽  
Jie Wang ◽  
Shidong Zhu ◽  
...  
Keyword(s):  
High Temperature ◽  
Chinese Cabbage ◽  
Photosynthetic Capacity ◽  
Photochemical Efficiency ◽  
Membrane Integrity ◽  
Photosynthetic Apparatus ◽  
Carbon Assimilation ◽  
Light Reaction ◽  
Chlorophyll Contents ◽  
Heat Tolerant

High temperature (HT) is a major environmental stress limiting oversummer production of nonheading Chinese cabbage (NHCC, Brassica campestris ssp. chinensis Makino). In the present study, the effects of HT on photosynthetic capacity, including light reaction and carbon assimilation, were completely investigated in two NHCC, ‘xd’ (heat-tolerant), and ‘sym’ (heat-susceptible). The two genotypes showed significant differences in plant morphology, photosynthetic capacity, and photosynthate metabolism (carboassimilation). HT caused a decrease in photosynthesis, chlorophyll contents, and photochemical activity in NHCC. However, these main photosynthetic-related parameters, including net photosynthetic rate (PN), maximal photochemical efficiency of PSII (Fv/Fm), and total chlorophyll content in ‘xd’, were significantly higher than those of ‘sym’ plants. The antioxidant contents and antioxidative enzyme activities of ascorbic acid-reduced glutathione cycle in the chloroplast of ‘xd’ were significantly higher than those of ‘sym’. Microscopic analyses revealed that HT affected the structure of photosynthetic apparatus and membrane integrity to a different extent, whereas ‘xd’ could maintain a better integrated chloroplast shape and thylakoid. Inhibited light reaction also hampered carbon assimilation, resulting in a decline of carboxylation efficiency and imbalance of carbohydrate metabolism. However, larger declined extents in these data were presented in ‘sym’ (heat-susceptible) than ‘xd’ (heat-tolerant). The heat-tolerant genotype ‘xd’ had a better capacity for self-protection by improved light reaction and carbon assimilation responding to HT stress.

scholarly journals Relationships among Isoprene Emission Rate, Photosynthesis, and Isoprene Synthase Activity as Influenced by Temperature

1992 ◽  
Vol 98 (3) ◽  
pp. 1175-1180 ◽  
Author(s):  
Russell K. Monson ◽  
Charles H. Jaeger ◽  
William W. Adams ◽  
Edward M. Driggers ◽  
Gary M. Silver ◽  
...  
Keyword(s):  
Emission Rate ◽  
Isoprene Emission ◽  
Isoprene Synthase

scholarly journals Heat stroke during long-term clozapine treatment: should we be concerned about hot weather?

2016 ◽  
Vol 38 (1) ◽  
pp. 56-59 ◽  
Author(s):  
Maurício Scopel Hoffmann ◽  
Lucas Mendes Oliveira ◽  
Maria Inês Rodrigues Lobato ◽  
Paulo Belmonte-de-Abreu
Keyword(s):  
Heat Stroke ◽  
Systemic Infection ◽  
Accurate Diagnosis ◽  
Pharmacological Intervention ◽  
Case Description ◽  
Clozapine Treatment ◽  
Improve Treatment ◽  
Clinical Events ◽  
Hot Weather

Objective To describe the case of a patient with schizophrenia on clozapine treatment who had an episode of heat stroke. Case description During a heat wave in January and February 2014, a patient with schizophrenia who was on treatment with clozapine was initially referred for differential diagnose between systemic infection and neuroleptic malignant syndrome, but was finally diagnosed with heat stroke and treated with control of body temperature and hydration. Comments This report aims to alert clinicians take this condition into consideration among other differential diagnoses, especially nowadays with the rise in global temperatures, and to highlight the need for accurate diagnosis of clinical events during pharmacological intervention, in order to improve treatment decisions and outcomes.

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