Effects of heat stress on gas exchange and photosystem II (PSII) photochemical activity of Phillyrea angustifolia exposed to elevated CO2 and subsaturating irradiance

Botany ◽  
2008 ◽  
Vol 86 (4) ◽  
pp. 435-441 ◽  
Author(s):  
Luca Vitale ◽  
Carmen Arena ◽  
Amalia Virzo De Santo ◽  
Nicola D’Ambrosio
Keyword(s):  
Heat Stress ◽  
Electron Transport ◽  
Gas Exchange ◽  
Photosystem Ii ◽  
Photochemical Efficiency ◽  
Calvin Cycle ◽  
Fluorescence Measurements ◽  
Significant Difference ◽  
Psii Photochemical Efficiency ◽  
Phillyrea Angustifolia

Gas exchange and chlorophyll a fluorescence measurements were performed simultaneously on leaves of Phillyrea angustifolia L. to assess the effects of heat stress (30 min at 40 °C) on photosynthesis and photosystem II (PSII) photochemical efficiency of plants grown at ambient CO2 and exposed to an elevated CO2 concentration (800 µmol·mol–1) and 300 µmol photons·m–2·s–1. No significant difference was found in the heat-induced decreases of net photosynthesis (PN), quantum yield of PSII electron transport (ΦPSII), and maximum PSII photochemical efficiency (Fv/Fm) between plants exposed to ambient and elevated CO2 concentrations, showing that elevated CO2 was not able to reduce the potential for photoinhibition at high temperatures under moderate light conditions. The heat-induced decrease of PN was higher than that of ΦPSII indicating that reductive power was more utilized in non-assimilatory processes than in CO2 fixation at both CO2 treatments. This result suggested that impairment of the Calvin cycle rather than electron transport inhibition was the main cause of the limitation in CO2 fixation.

scholarly journals Heat Tolerance of Five Taxa of Birch (Betula): Physiological Responses to Supraoptimal Leaf Temperatures

1994 ◽  
Vol 119 (2) ◽  
pp. 243-248 ◽  
Author(s):  
Thomas G. Ranney ◽  
Mary M. Peet
Keyword(s):  
Gas Exchange ◽  
High Temperatures ◽  
Heat Tolerance ◽  
Leaf Gas Exchange ◽  
Photochemical Efficiency ◽  
Calvin Cycle ◽  
Differential Sensitivity ◽  
Ps Ii ◽  
Fluorescence Measurements ◽  
Paper Birch

Leaf gas-exchange and chlorophyll fluorescence measurements were used as indexes for evaluating heat tolerance among five taxa of birch: paper (Betula papyrifera Marsh.), European (B. pendula Roth.), Japanese (B. platyphylla var. japonica Hara. cv. Whitespire), Himalayan (B. jacquemontii Spach.), and river (B. nigra L. cv. Heritage). Gas-exchange measurements were conducted on individual leaves at temperatures ranging from 25 to 40C. River birch maintained the highest net photosynthetic rates (Pn) at high temperatures, while Pn of paper birch was reduced the most. Further study of river and paper birch indicated that the reduced Pn at high temperatures and the differential sensitivity between taxa resulted from several factors. Inhibition of Pn at higher temperatures was due largely to nonstomatal limitations for both taxa. Increases in respiration rates, decreases in maximal photochemical efficiency of photosystem (PS) II (FV/FM), and possible reductions in light energy directed to PS II (F0 quenching) were apparent for both taxa. The capacity of river birch to maintain greater Pn at higher temperatures seemed to result from a lower Q10 for dark respiration and possibly greater thermotolerance of the Calvin cycle as indicated by a lack of nonphotochemical fluorescence quenching with increasing temperatures. Thermal injury, as indicated by a rapid increase in minimal, dark-acclimated (F0) fluorescence, was not evident for either paper or river birch until temperatures reached ≈49C and was similar for both taxa.

Simultaneous Gas-Exchange and Fluorescence Measurements with Ozone-Fumigated Spruce

1994 ◽  
Vol 49 (11-12) ◽  
pp. 819-833
Author(s):  
Stefan Drenkard ◽  
Jürgen Maguhn ◽  
Dietmar Knoppik
Keyword(s):  
Gas Exchange ◽  
Calvin Cycle ◽  
Photosynthetic Apparatus ◽  
Early Summer ◽  
Assimilation Rate ◽  
Light Reaction ◽  
Fluorescence Measurements ◽  
Transport Chain ◽  
Short Time ◽  
Supply Information

A method was developed for carrying out gas-exchange and chlorophyll-fluorescence measurements simultaneously during fumigation of spruce twigs with peroxidic photooxidants. It is thus now possible to investigate how a pollutant affects distinct sectors of the photosynthetic apparatus of the plant: whereas fluorescence reveals any changes in the primary light reaction, CO2 gas-exchange measurements supply information about the biochemical reactions of the Calvin cycle. Results of short-time fumigation with 750 ppb ozone are presented here. Gas-exchange and fluorescence data are affected strongly in early summer, but not in autumn. The assimilation rate decreases significantly: primarily as a result of Rubisco activity and possibly because of direct inhibition of the electron-transport chain as well. Closure of the stomata leads to further reduction in the assimilation rate. Though no damage becomes visible on the needles, the perturbance of the photosynthetic apparatus caused by ozone fumigation is not reversible within 24 h.

scholarly journals Progesterone increases photochemical efficiency of photosystem II in wheat under heat stress by facilitating D1 protein phosphorylation

2017 ◽  
Vol 55 (4) ◽  
pp. 664-670 ◽  
Author(s):  
R. L. Xue ◽  
S. Q. Wang ◽  
H. L. Xu ◽  
P. J. Zhang ◽  
H. Li ◽  
...  
Keyword(s):  
Heat Stress ◽  
Photosystem Ii ◽  
Protein Phosphorylation ◽  
Photochemical Efficiency ◽  
D1 Protein

The sun-exposed peel of apple fruit has a higher photosynthetic capacity than the shaded peel

2007 ◽  
Vol 34 (11) ◽  
pp. 1038 ◽  
Author(s):  
Li-Song Chen ◽  
Lailiang Cheng
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Oxygen Evolution ◽  
Photosynthetic Capacity ◽  
Light Exposure ◽  
Calvin Cycle ◽  
Apple Fruit ◽  
Thermal Dissipation ◽  
The Sun ◽  
Significant Difference

To determine whether the sun-exposed peel of apple fruit has a higher photosynthetic capacity than the shaded peel, fruit peel samples were taken in both early July and early September from the exterior part of the canopy of mature ‘Liberty’/M.9 trees for measuring oxygen evolution, key enzymes and metabolites involved in photosynthesis, and chlorophyll fluorescence. Compared with the shaded peel, the sun-exposed peel had higher light-saturated oxygen evolution rate and higher light saturation point, but lower apparent and true quantum yields. The activity of ribulose-1,5-bisphosphate carboxylase/oxygenase, glyceraldehyde-3-phosphate dehydrogenase, phosphoribulokinase, stromal fructose-1,6-bisphosphatase, ADP-glucose pyrophosphorylase and sucrose-phosphate synthase (SPS) were higher in the sun-exposed peel than in the shaded peel on both sampling dates except that no significant difference was found in SPS activity between the two peel types in September. No significant difference was detected in the concentration of key metabolites (G6P, F6P, G1P, and PGA) between the sun-exposed peel and the shaded peel, suggesting that the response of the key enzymes to light exposure is well coordinated. Chlorophyll fluorescence quenching analysis showed that the sun-exposed peel had higher PSII quantum efficiency than the shaded peel at each given PFD, which resulted mainly from the higher photochemical quenching coefficient (qP). The sun-exposed peel had higher thermal dissipation capacity, as indicated by larger NPQ and Fo quenching, than the shaded peel at high PFD. In conclusion, the sun-exposed peel of apple fruit has higher activities of the Calvin cycle enzymes and higher rate of electron transport, leading to higher photosynthetic O2 evolution capacity. It appears that the acclimation of the Calvin cycle activities, thermal dissipation, and electron transport in apple peel are well coordinated in response to light exposure.

DROUGHT TOLERANCE IN MULBERRY (MORUS SPP.): A PHYSIOLOGICAL APPROACH WITH INSIGHTS INTO GROWTH DYNAMICS AND LEAF YIELD PRODUCTION

2010 ◽  
Vol 46 (4) ◽  
pp. 471-488 ◽  
Author(s):  
ANIRBAN GUHA ◽  
GIRISH KUMAR RASINENI ◽  
ATTIPALLI RAMACHANDRA REDDY
Keyword(s):  
Gas Exchange ◽  
Photosystem Ii ◽  
Drought Tolerance ◽  
Leaf Gas Exchange ◽  
Growth Dynamics ◽  
Growing Season ◽  
Physiological Variables ◽  
Fluorescence Measurements ◽  
Yield Production ◽  
Leaf Yield

SUMMARYThe present study documents critical analysis of drought-induced physiological responses in mulberry (Morus spp.) with insights into growth dynamics and leaf productivity. The study was performed for two years in a two-phase experimental design combining both field (experiment no. 1) and glasshouse (experiment no. 2) observations. In field assays, we surveyed 15 mulberry genotypes under two irrigation regimes: well-watered (20 to 24 irrigations in each growing season) and water-limited (irrigated once in a fortnight in each growing season). The genotypes were assessed for variation in key leaf gas exchange characteristics: net photosynthetic rates (Pn), stomatal conductance of CO2 (gs), transpiration rates (E) and instantaneous water use efficiency (WUEi). Leaf yield/plant was considered to determine the tolerance index (TI). Drought stress severely down-regulated leaf-level physiological variables in the susceptible genotypes resulting in poor leaf yield. However, genotypes S-13 and V-1 performed better in terms of leaf gas exchange and proved their superiority over other genotypes in drought tolerance. Conversely, genotypes DD and Bogurai were highly susceptible to drought. Under glasshouse conditions, the combined leaf gas exchange/chlorophyll a fluorescence measurements further dissected out stomatal and non-stomatal restrictions to Pn. As internal/ambient CO2 ratio (Ci/Ca) decreased concurrently with gs in non-irrigated stands, it appeared that greater stomatal limitation to Pn was associated with decreased photo-assimilation and leaf yield production. Further, higher leaf temperature (TL) (>35 °C) and down-regulation of maximum quantum yield of photosystem II (Fv/Fm) were apparent in the susceptible compared to the tolerant genotypes, which indicated chronic photoinhibition due to photo-inactivation of photosystem II centres in the susceptible genotypes. Drought-induced trade-offs in biomass allocation were also highlighted. Overall, our results suggest that greater rooting vigour and leaf hydration status, minimal stomatal inhibition and stabilized photochemistry might play major roles in maintaining higher Pn and associated gas exchange functions in drought-tolerant mulberry genotypes under water stress conditions. The higher leaf yield production in tolerant than susceptible genotypes can be attributed to minimal plasticity in foliar gas exchange traits and better quantitative growth characteristics under low water regimes.

SO2 Injury in Intact Leaves, as Detected by Chlorophyll Fluorescence

1988 ◽  
Vol 43 (3-4) ◽  
pp. 269-274 ◽  
Author(s):  
Wolfgang Schmidt ◽  
Ulrich Schreiber ◽  
Wolfgang Urbach
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Calvin Cycle ◽  
Photosynthetic Apparatus ◽  
Enzymatic Reactions ◽  
Decay Kinetics ◽  
Saturation Pulse ◽  
Induction Kinetics ◽  
Fluorescence Measurements

The effects of short-time fumigation (0-60 min) of intact spinach leaves with SO2 (2 ppm) on the photosynthetic apparatus were investigated. A rather high SO2 concentration was applied to monitor immediate effects on the fluorescence behaviour with the influence of repair processes or secondary types of damage being minimized. Three different types of in vivo chlorophyll fluorescence measurements were used: Rapid induction kinetics (Kautsky effect), slow induction kinetics with repetitive application of saturation pulses (saturation pulse method), and decay kinetics following a single turnover saturating flash. The slow induction kinetics with repetitive application of saturation pulses reacts in the most sensitive way indicating a primary damage at the level of the enzymatic reactions of the Calvin cycle. It is suggested that stromal acidification upon SO2 uptake interferes with light activation of Calvin cycle enzymes. With longer fumigation times also damage at the level of photosystem II becomes apparent: A decrease in variable fluorescence yield reflects a lowering of photosystem II quantum yield, and the slowing down of fluorescence relaxation kinetics reveals an effect on the secondary electron transport from Qᴀ to Qв. The detrimental effects of SO2 depend to a great extent on the application of light during fumigation. Besides a light requirement for SO2 uptake by stomata opening also the possibility of photoinhibitory damage is discussed. The susceptibility of leaves to photoinhibition may increase with a lowering of Calvin cycle activity by SO2.

scholarly journals THE EFFECTS OF ALUMINIUM ON THE PHOTOSYNTHETIC APPARATUS OF TWO RICE CULTIVARS

2013 ◽  
Vol 50 (3) ◽  
pp. 343-352 ◽  
Author(s):  
E. M. FONSECA JÚNIOR ◽  
J. CAMBRAIA ◽  
C. RIBEIRO ◽  
M. A. OLIVA ◽  
J. A. OLIVEIRA ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photochemical Efficiency ◽  
Photosynthetic Apparatus ◽  
Carbon Assimilation ◽  
Biomass Accumulation ◽  
Dry Mass ◽  
Photochemical Quenching ◽  
Photosynthetic Parameters ◽  
Rice Cultivars

SUMMARYWe aimed to evaluate aluminium (Al) effects on the photosynthetic apparatus of two rice cultivars with contrasting tolerances to Al. Nine-days-old seedlings were exposed to 0 or 1 mM Al for 10 days, and then dry mass, Al and chloroplastidic pigment contents and photosynthetic parameters were determined. Al accumulated mainly in the roots of the Al-treated plants. In the leaves, Al increased only in the sensitive cultivar, but there was no difference between the cultivars in Al-treated plants. The root and leaf dry mass, the net carbon assimilation rate, stomatal conductance and internal CO2 concentration were all reduced in response to Al application, but only in the sensitive cultivar. Both the initial fluorescence and potential photochemical efficiency of photosystem II were unresponsive to the Al treatments, regardless of the cultivar. In the Al-sensitive cultivar, Al provoked significant decreases in the photochemical quenching coefficient, quantum yield of photosystem II electron transport and apparent electron transport rate, in parallel to an unaltered non-photochemical quenching coefficient. All of these parameters remained at the control levels in the tolerant cultivar. The chloroplastidic pigment content increased only in the Al-tolerant cultivar, whereas it remained unaltered after Al treatment in the sensitive cultivar. In conclusion, Al induced stomatal and (most likely) photochemical constraints on photosynthesis but with no apparent signs of photoinhibition in the Al-sensitive cultivar. Despite the similar Al levels of the cultivars, unchanging biomass accumulation or photosynthetic performance in the tolerant cultivar challenged with Al highlights its higher intrinsic ability to cope with Al stress.

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