Assimilate Movement in Lolium and Sorghum Leaves. Iii. Carbon Dioxide Concentration Effects on the Metabolism and Translocation of Photosynthate.

1982 ◽  
Vol 9 (6) ◽  
pp. 705 ◽  
Author(s):  
IF Wardlaw
Keyword(s):  
Water Stress ◽  
Stomatal Closure ◽  
Carbon Dioxide Concentration ◽  
Co2 Concentration ◽  
Co2 Exchange ◽  
Co2 Uptake ◽  
Concentration Effects ◽  
Low Light ◽  
Low Co2 ◽  
Before And After

Raising the CO2 concentration of air to 720 �l I-� increased the rate of net CO2 uptake by the leaf of Lolium temulentum, a C*3 species, more than in Sorghum sudanense, a C*4 species. In Lolium, but not in Sorghum, high CO2 over a 6 h period resulted in relatively more of the additional leaf photosynthate being partitioned into storage rather than to translocation. Removing CO2 from the air passing over a 5 cm length of leaf before and after a pulse application of 14CO2 resulted in a reduced labelling of sucrose and a slower rate of export of 14C-labelled photosynthate in both species. With the fall in net CO2 exchange by the leaf section deprived of CO2 there was a compensating increase within this section in retention of photosynthate derived from the distal part of the leaf. Evidence provided by 14CO2 pulse chase experiments and CO2 exchange studies confirmed the relative enhancement of photorespiration under low CO2 concentrations in Lolium, but not in Sorghum. The CO2 depletion experiments provide a useful base for comparison with the effect of low light and water stress on photosynthate metabolism and translocation in that both these conditions reduce CO2 uptake. There is support for the suggestion that the change in photosynthate metabolism under water stress in C*3 species may result from reduced CO2 entry into the leaf due to stomatal closure.

scholarly journals Using New Gas Exchange Methods to Estimate Mesophyll Conductance and Non-stomatal Inhibition of Photosynthesis Caused by Water Deficits

HortScience ◽  
2012 ◽  
Vol 47 (6) ◽  
pp. 687-690 ◽  
Author(s):  
James Bunce
Keyword(s):  
Carbon Dioxide ◽  
Water Stress ◽  
Soil Water ◽  
Atmospheric Carbon Dioxide ◽  
Global Climate ◽  
Stomatal Closure ◽  
Carbon Dioxide Concentration ◽  
Mesophyll Conductance ◽  
Water Deficits ◽  
Air Space

Soil water deficits remain one of the most important factors reducing the yield of crop plants and may become even more limiting with changes in the global climate and competition for fresh water resources. Soil water deficits reduce plant growth partly by reducing photosynthesis. However, it remains unclear how important non-stomatal factors are in limiting photosynthesis under moderate water stress and whether rising atmospheric carbon dioxide may alter which processes limit photosynthesis under water stress. The conductance to CO2 from the substomatal air space to the site of carboxylation inside chloroplasts in C3 plants is now termed mesophyll conductance. Because of the competition between CO2 and O2 for RuBisco, the carbon dioxide concentration at the chloroplast can be estimated from the O2 sensitivity of photosynthesis, providing a new method of estimating mesophyll conductance. It has also recently been realized that partial stomatal closure resulting from water stress can often be reversed by exposing leaves to low CO2. This provides a new means of assessing the non-stomatal component of the inhibition of photosynthesis by water stress. These methods were applied to four C3 species and revealed that mesophyll conductance decreased substantially with water stress in two of the four species and that reopening of stomata did not eliminate the reduction in photosynthesis caused by moderate water stress at either the current ambient or elevated CO2 concentrations.

scholarly journals Activation Energy Analysis and Limiting Factors in Photosynthesis

1972 ◽  
Vol 25 (2) ◽  
pp. 419 ◽  
Author(s):  
RM Gifford ◽  
RB Musgrave
Keyword(s):  
Activation Energy ◽  
Temperature Response ◽  
Co2 Concentration ◽  
Co2 Exchange ◽  
Photochemical Reactions ◽  
High Light ◽  
Limiting Factors ◽  
Grass Species ◽  
Low Co2 ◽  
Rate Limiting

It has been proposed that activation energies of CO2 exchange obtained from Arrhenius plots of the temperature response of leaf CO2 exchange rates (or the equivalent QIO analysis) should elucidate the rate-limiting processes. Chmora and Oya (1967), for example, suggest that a QlO (15-25�0) of about 1 for maize photo-synthesis at low light and low CO2 concentration implies photochemical reactions are limiting, at high light and high CO2 a QIO of 1 �6 implies enzyme reactions are limiting, whilst at high light and low CO2 a QlO of 1� 25 suggests diffusion is limiting. Bjorkman, Nobs, and Hiesey (1969) surmise that for Mimulus sp. at 0�07% CO2 the coincidence of QIO (15-30�0) for both CO2 exchange (at 1'5% oxygen and saturating light) and extracted carboxydismutase (QlO = 2�7-3�3) could reflect a causal relationship. Charles-Edwards and Charles-Edwards (1970) find that for clones of three grass species there is a clustering of the determinations of activation energy around certain values. It is suggested that each such value may be characteristic of a certain rate-limiting process.

Post-illumination CO2 Exchange and Light-induced CO2 Bursts during C4 Photosynthesis

1997 ◽  
Vol 24 (4) ◽  
pp. 517 ◽  
Author(s):  
Agu Laisk ◽  
Gerald E. Edwards
Keyword(s):  
Malic Enzyme ◽  
Co2 Exchange ◽  
Co2 Uptake ◽  
Low Light ◽  
Co2 Response ◽  
Amaranthus Cruentus ◽  
Dark Light ◽  
Gas System ◽  
Detailed Kinetics ◽  
Kinetics Of

Detailed kinetics of the post-illumination CO2 exchange, and darklight transients following post-illumination exchange, were measured in leaves of Sorghum bicolor, a NADP-malic enzyme (NADP-ME), and Amaranthus cruentus, a NAD-malic enzyme (NAD-ME) type C4 plant using a gas system that has a full-response time of 3.5 s. The amount of CO2 fixed in the dark (assimilatory charge, AC) was up to 200 µmol m-2 for A. cruentus and 350-450 µmol m-2 for S. bicolor. AC was at its maximum value at CO2 concentrations close to the inflection of the CO2 response curve, and decreased when photosynthesis was limited by low light intensity. The kinetics of post-illumination CO2 fixation indicate that the rate of carboxylation in the C4 cycle is limited by the supply of phosphoenolpyruvate. In A. cruentus, under saturating CO2 the post-illumination CO2 uptake was replaced by a burst (68 µmol m-2). In S. bicolor, the dark-light induction commenced with a rapid CO2 burst (less than 5 s) of 46 µmol m-2, followed by a gulp. The observed CO2 transients show imbalances in the C4 and C3 cycles. In S. bicolor the lack of a post-illumination burst, and the presence of the light- induced CO2 burst is taken as evidence for strict coupling of malate decarboxylation to PGA reduction in NADP-ME species; the opposite response in A. cruentus indicates the lack of strict coupling between the C4 and C3 cycle in NAD-ME species.

Do mycorrhizas improve tropical tree seedling performance under water stress and low light conditions? A case study with Dicorynia guianensis (Caesalpiniaceae)

2005 ◽  
Vol 21 (4) ◽  
pp. 375-381 ◽  
Author(s):  
Moïse Béreau ◽  
Damien Bonal ◽  
Eliane Louisanna ◽  
Jean Garbaye
Keyword(s):  
Water Stress ◽  
Carbon Allocation ◽  
Stomatal Closure ◽  
Phosphorus Uptake ◽  
Carbon Assimilation ◽  
Mycorrhizal Symbiosis ◽  
Light Conditions ◽  
Tree Seedling ◽  
Low Light ◽  
Dicorynia Guianensis

We tested the response of seedlings of Dicorynia guianensis, a major timber tree species of French Guiana, to mycorrhizal symbiosis and water limitation in a semi-controlled experiment under natural light conditions. Under well-watered conditions, mycorrhizal colonization resulted in an increase of net photosynthesis, growth and phosphorus uptake. When submitted to water stress, no growth reduction of mycorrhizal seedlings was observed. Mycorrhizal seedlings were more sensitive to drought than non-mycorrhizal ones in terms of carbon assimilation, but not with regard to stomatal closure. In contrast to previous studies on temperate tree seedlings, this result precludes a mycorrhizal effect on the hydraulic properties of this species. Furthermore, our results suggest that below a specific threshold of soil moisture, carbon assimilation of D. guianensis seedlings was decreased by the mycorrhizal symbiosis. This is probably related to the competition between the plant and its host fungus for carbon allocation under low light intensity, even though it did not seem to have a significant effect on mortality in our experiment.

scholarly journals Characterizing Concentration Effects of Exogenous Abscisic Acid on Gas Exchange, Water Relations, and Growth of Muskmelon Seedlings during Water Stress and Rehydration

2012 ◽  
Vol 137 (6) ◽  
pp. 400-410 ◽  
Author(s):  
Shinsuke Agehara ◽  
Daniel I. Leskovar
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Gas Exchange ◽  
Water Status ◽  
Stomatal Closure ◽  
Membrane Integrity ◽  
Dry Matter Accumulation ◽  
Assimilation Rate ◽  
Concentration Effects ◽  
Post Stress

Excess transpiration relative to water uptake often causes water stress in transplanted vegetable seedlings. Abscisic acid (ABA) can limit transpirational water loss by inducing stomatal closure and inhibiting leaf expansion. We examined the concentration effect of exogenous ABA on growth and physiology of muskmelon (Cucumis melo L.) seedlings during water stress and rehydration. Plants were treated with seven concentrations of ABA (0, 0.24, 0.47, 0.95, 1.89, 3.78, and 7.57 mm) and subjected to 4-day water withholding. Application of ABA improved the maintenance of leaf water potential and relative water content, while reducing electrolyte leakage. These effects were linear or exponential to ABA concentration and maximized at 7.57 mm. Gas-exchange measurements provided evidence that such stress control is attributed to ABA-induced stomatal closure. First, net CO2 assimilation rate and stomatal conductance initially decreased with increasing ABA concentration by up to 95% and 70%, respectively. A follow-up study (≤1.89 mm ABA) confirmed this result with or without water stress and further revealed a close positive correlation between intercellular CO2 concentration and net CO2 assimilation rate 1 day after treatment (r2 > 0.83). In contrast, ABA did not affect leaf elongation, indicating that stress alleviation was not mediated by leaf area adjustment. After 18 days of post-stress daily irrigation, dry matter accumulation showed a quadratic concentration-response, increasing up to 1.89 mm by 38% and 44% in shoot and roots, respectively, followed by 16% to 18% decreases at >1.89 mm ABA. These results suggest that excess levels of ABA delay post-stress growth, despite the positive effect on the maintenance of water status and membrane integrity. Another negative side effect was chlorosis, which accelerated linearly with increasing ABA concentration, although it was reversible upon re-watering. The optimal application rate of ABA should minimize these negative effects, while keeping plant water stress to an acceptable level.

scholarly journals Sea-Air CO2 Exchange in the SW Iberian Upwelling System during Two Contrasting Climate Cycles: 860–780 ka and 630–520 ka

Geosciences ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 454
Author(s):  
Gloria Martin-Garcia
Keyword(s):  
Source Area ◽  
Co2 Exchange ◽  
Meridional Overturning Circulation ◽  
Co2 Uptake ◽  
Low Carbon ◽  
High Productivity ◽  
The North ◽  
Climate Cycles ◽  
Before And After ◽  
Iberian Margin

Analysis of planktonic and benthic foraminifers’ accumulation rates from the Iberian margin reveal a substantial change in the biogenic ocean-atmosphere CO2 exchange during the Mid-Pleistocene Transition (MPT; ~800–650 ka from present). Such changes resulted from the major reorganisations in both surface and deep-water circulation that occurred in the North Atlantic at the time, and affected the behaviour of this upwelling region as a CO2 uptake/release area during climate cycles before and after the MPT. During Marine Isotope Stages (MIS) 21-MIS 20 (860–780 ka), this margin acted mostly as an uptake area during interglacials and early glacials. During glacial maxima and terminations it would be neutral because, although surface production and export were very low, carbon storage occurred at the seafloor. During MIS 15-MIS 14 (630–520 ka), the pattern was the opposite, and the Iberian margin worked as a neutral, or as a source area during most interglacials, while during glacials it acted as an important uptake area. Present findings support the idea that glacial/interglacial atmospheric pCO2 oscillations are partly driven by alterations in the meridional overturning circulation that results in substantial variations of the biological pump, and carbon sequestration rate, in some high-productivity regions.

scholarly journals Grafting cv. Grechetto Gentile Vines to New M4 Rootstock Improves Leaf Gas Exchange and Water Status as Compared to Commercial 1103P Rootstock

Agronomy ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 708 ◽  
Author(s):  
Tommaso Frioni ◽  
Arianna Biagioni ◽  
Cecilia Squeri ◽  
Sergio Tombesi ◽  
Matteo Gatti ◽  
...  
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Water Use ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Summer Drought ◽  
Co2 Uptake ◽  
Drought Tolerant

M4 is a relatively new rootstock that was selected for increased resilience of vineyards across hot regions where meteorological drought is often coupled to water scarcity. However, M4 has thus far been tested only against water-stress sensitive rootstocks. Against this backdrop, the aim of the present work is to examine the water status and gas exchange performances of vines grafted to M4 in comparison to those of vines grafted to a commercial stock that is drought-tolerant, 1103 Paulsen (1103P), under a progressive water deficit followed by re-watering. This study was undertaken on Grechetto Gentile, a cultivar that is renowned for its rather conservative water use (near-isohydric behavior). While fifty percent of both grafts were fully irrigated (WW), the remaining underwent progressive water stress by means of suspending irrigation (WS). Soil and leaf water status, as well as leaf gas exchanges, along with chlorophyll fluorescence, were followed daily from 1 day pre-stress (DOY 176) until re-watering (DOY 184). Final leaf area per vine, divided in main and lateral contribution, was also assessed. While 1103P grafted vines manifested higher water use under WW conditions, progressive stress evidenced a faster water depletion by 1103P, which also maintained slightly more negative midday leaf water potential (Ψleaf) as compared to M4 grafted plants. Daily gas exchange readings, as well as diurnal assessment performed at the peak of stress (DOY 183), also showed increased leaf assimilation rates (A) and water use efficiency (WUE) in vines grafted on M4, which were also less susceptible to photosynthetic downregulation. Dynamic of stomatal closure targeted at 90% reduction of leaf stomatal conductance showed a similar behavior among rootstocks since the above threshold was reached by both at Ψleaf of about −1.11 MPa. The same fractional reduction in leaf A was reached by vines grafted on M4 at a Ψleaf of −1.28 MPa vs. −1.10 MPa measured in 1103P, meaning that using M4 as a rootstock will postpone full stomatal closure. While mechanisms involved in improved CO2 uptake in M4-grafted vines under moderate-to-severe stress are still unclear, our data support the hypothesis that M4 might outscore the performance of a commercial drought-tolerant genotype (1103P) and can be profitably used as a tool to improve the resilience of vines to summer drought.

Relationship between the inhibition of leaf respiration by light and enhancement of leaf dark respiration following light treatment

1998 ◽  
Vol 25 (4) ◽  
pp. 437 ◽  
Author(s):  
Owen K. Atkin ◽  
John R. Evans ◽  
Katharina Siebke
Keyword(s):  
Dark Respiration ◽  
Intercellular Co2 Concentration ◽  
Co2 Concentration ◽  
Fast Response ◽  
Co2 Exchange ◽  
Common Mechanism ◽  
Low Co2 ◽  
Leaf Dark Respiration ◽  
Co2 Release ◽  
Intercellular Co2

Respiration (R, non-photorespiratory mitochondrial CO2 release) in leaves is inhibited by light. However, exposure to darkness after a period of illumination can also result in R being temporarily stimulated (termed ‘light enhanced dark respiration’, LEDR). We used a fast-response CO2 exchange system to investigate these observations in tobacco leaves. After switching off the light, there were two peaks of CO2 release, the first at 15–20 s (the photorespiratory post-illumination burst) and the second at 180–250 s (LEDR). LEDR occurred in all post-illumination experiments, independent of O2 or CO2 concentration. However, LEDR increased with increasing irradiance during the pre-dark period, suggesting some dependency on prior photosynthesis. We investigated the inhibition of R by light at low CO2 concentrations (?*): ?* is the intercellular CO2 concentration at which net CO2 release represents R in the light. The inhibition of R in the light took about 50 s and was even evident at 3 mmol photons m-2 s-1, regardless of the light quality (red, blue or white). The inhibition of R by light showed similar dependency on irradiance as LEDR, such that the degree of inhibition was positively correlated with the level of LEDR. In the light, switching from 350 ppm to a low CO2 concentration that resulted in the intercellular CO2 concentration being at ?*, resulted in R initially increasing and then stabilising. Maintaining the leaf at ?* did not, therefore, lead to an underestimation of R. Our data suggest that a common mechanism may be responsible for both the inhibition of R by light and LEDR.

Crassulacean Acid Metabolism and Diurnal Variations of Internal CO2 and O2 Concentrations in Sedum praealtum DC

1979 ◽  
Vol 6 (4) ◽  
pp. 557 ◽  
Author(s):  
MH Spalding ◽  
DK Stumpf ◽  
MSB Ku ◽  
RH Burris ◽  
GE Edwards
Keyword(s):  
Malic Acid ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Dark Period ◽  
Stomatal Closure ◽  
Co2 Concentration ◽  
Co2 Exchange ◽  
C3 Plants ◽  
Cam Plants ◽  
Internal Co2

Internal CO2 and O2 concentrations in Sedum praealtum DC. were determined by gas chromatography of 200-�l gas samples. Day-night monitoring showed that internal CO2 varied from a high of approximately 4000 �l/l during periods of daytime stomatal closure to a low of 270-280 �l/l during the dark period (stomata open). Internal O2 concentrations varied from a high of approximately 26 % at midday to a low of 20.8 % during the dark period. The calculated internal O2/CO2 ratio varied about 12-15-fold from 50-60 near midday to approximately 750 during the dark period (ratio in normal air is roughly 600). Day-night patterns of CO2 exchange and malic acid concentration were typical for a plant with crassulacean acid metabolism (CAM). Influx of CO2 during the late light period was inhibited by O2, but dark CO2 influx was O2-insensitive. Gas samples taken near midday from several CAM plants all showed elevated internal CO2 and O2 concentrations. Ratios of O2/CO2 in these plants ranged from 81 in Sedum praealtum to 285 in Hoya carnosa. The highest internal O2 concentration observed was 41.5% in Kalanchoe gastonis-bonnieri. The high CO2 concentration in leaves of CAM plants during daytime stomatal closure should provide a near- saturating level of this substrate for photosynthesis. In comparison to C3 plants, the relatively low O2/CO2 ratio in the CAM leaf during malic acid decarboxylation should be favourable for photosynthesis and unfavourable for O2 inhibition of photosynthesis.

scholarly journals Light and CO2 Modulate the Accumulation and Localization of Phenolic Compounds in Barley Leaves

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 385
Author(s):  
Lena Hunt ◽  
Karel Klem ◽  
Zuzana Lhotáková ◽  
Stanislav Vosolsobě ◽  
Michal Oravec ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Phenolic Compounds ◽  
Co2 Concentration ◽  
Environmental Stressors ◽  
Low Light ◽  
Mesophyll Cells ◽  
Stress Prevention ◽  
Tolerant Variety ◽  
Barley Leaves

Barley (Hordeum vulgare) accumulates phenolic compounds (PhCs), which play a key role in plant defense against environmental stressors as antioxidants or UV screening compounds. The influence of light and atmospheric CO2 concentration ([CO2]) on the accumulation and localization of PhCs in barley leaves was examined for two varieties with different tolerances to oxidative stress. PhC localization was visualized in vivo using fluorescence microscopy. Close relationships were found between fluorescence-determined localization of PhCs in barley leaves and PhC content estimated using liquid chromatography coupled with mass spectroscopy detection. Light intensity had the strongest effect on the accumulation of PhCs, but the total PhC content was similar at elevated [CO2], minimizing the differences between high and low light. PhCs localized preferentially near the surfaces of leaves, but under low light, an increasing allocation of PhCs in deeper mesophyll layers was observed. The PhC profile was significantly different between barley varieties. The relatively tolerant variety accumulated significantly more hydroxycinnamic acids, indicating that these PhCs may play a more prominent role in oxidative stress prevention. Our research presents novel evidence that [CO2] modulates the accumulation of PhCs in barley leaves. Mesophyll cells, rather than epidermal cells, were most responsive to environmental stimuli in terms of PhC accumulation.

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