scholarly journals Barley Genotypes Vary in Stomatal Responsiveness to Light and CO2 Conditions

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2533
Author(s):  
Lena Hunt ◽  
Michal Fuksa ◽  
Karel Klem ◽  
Zuzana Lhotáková ◽  
Michal Oravec ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Abscisic Acid ◽  
Stomatal Conductance ◽  
Light Intensity ◽  
Stomatal Density ◽  
Co2 Concentration ◽  
High Light ◽  
Environmental Drivers ◽  
Sugar Accumulation ◽  
Barley Genotypes

Changes in stomatal conductance and density allow plants to acclimate to changing environmental conditions. In the present paper, the influence of atmospheric CO2 concentration and light intensity on stomata were investigated for two barley genotypes—Barke and Bojos, differing in their sensitivity to oxidative stress and phenolic acid profiles. A novel approach for stomatal density analysis was used—a pair of convolution neural networks were developed to automatically identify and count stomata on epidermal micrographs. Stomatal density in barley was influenced by genotype, as well as by light and CO2 conditions. Low CO2 conditions resulted in increased stomatal density, although differences between ambient and elevated CO2 were not significant. High light intensity increased stomatal density compared to low light intensity in both barley varieties and all CO2 treatments. Changes in stomatal conductance were also measured alongside the accumulation of pentoses, hexoses, disaccharides, and abscisic acid detected by liquid chromatography coupled with mass spectrometry. High light increased the accumulation of all sugars and reduced abscisic acid levels. Abscisic acid was influenced by all factors—light, CO2, and genotype—in combination. Differences were discovered between the two barley varieties: oxidative stress sensitive Barke demonstrated higher stomatal density, but lower conductance and better water use efficiency (WUE) than oxidative stress resistant Bojos at saturating light intensity. Barke also showed greater variability between treatments in measurements of stomatal density, sugar accumulation, and abscisic levels, implying that it may be more responsive to environmental drivers influencing water relations in the plant.

Altitude of origin influences stomatal conductance and therefore maximum assimilation rate in Southern Beech, Nothofagus cunninghamii

2000 ◽  
Vol 27 (5) ◽  
pp. 451 ◽  
Author(s):  
Mark J. Hovenden ◽  
Tim Brodribb
Keyword(s):  
Stomatal Conductance ◽  
Stomatal Density ◽  
Carbon Assimilation ◽  
Co2 Concentration ◽  
Carboxylation Efficiency ◽  
Assimilation Rate ◽  
Carbon Assimilation Rate ◽  
Southern Beech ◽  
Maximum Stomatal Conductance ◽  
Leaf Biochemistry

Gas exchange measurements were made on saplings of Southern Beech, Nothofagus cunninghamii (Hook.) Oerst. collected from three altitudes (350, 780 and 1100 m above sea level) and grown in a common glasshouse trial. Plants were grown from cuttings taken 2 years earlier from a number of plants at each altitude in Mt Field National Park, Tasmania. Stomatal density increased with increasing altitude of origin, and stomatal con-ductance and carbon assimilation rate were linearly related across all samples. The altitude of origin influenced thestomatal conductance and therefore carbon assimilation rate, with plants from 780 m having a greater photosynthetic rate than those from 350 m. The intercellular concentration of CO2 as a ratio of external CO2 concentration (ci/ca) was similar in all plants despite the large variation in maximum stomatal conductance. Carboxylation efficiency was greater in plants from 780 m than in plants from 350 m. Altitude of origin has a strong influence on the photo-synthetic performance of N. cunninghamii plants even when grown under controlled conditions, and this influence is expressed in both leaf biochemistry (carboxylation efficiency) and leaf morphology (stomatal density).

Stomatal aperture can compensate altered stomatal density in Arabidopsis thaliana at growth light conditions

2006 ◽  
Vol 33 (11) ◽  
pp. 1037 ◽  
Author(s):  
Dirk Büssis ◽  
Uritza von Groll ◽  
Joachim Fisahn ◽  
Thomas Altmann
Keyword(s):  
Arabidopsis Thaliana ◽  
Stomatal Conductance ◽  
Stomatal Density ◽  
Co2 Assimilation ◽  
High Light ◽  
Stomatal Aperture ◽  
Photochemical Quenching ◽  
Light Conditions ◽  
Wild Type ◽  
Light Intensities

Stomatal density of transgenic Arabidopsis thaliana plants over-expressing the SDD1 (stomatal density and distribution) gene was reduced to 40% and in the sdd1-1 mutant increased to 300% of the wild type. CO2 assimilation rate and stomatal conductance of over-expressers and the sdd1-1 mutant were unchanged compared with wild types when measured under the light conditions the plants were exposed to during growth. Lower stomatal density was compensated for by increased stomatal aperture and conversely, increased stomatal density was compensated for by reduced stomatal aperture. At high light intensities the assimilation rates and stomatal conductance of SDD1 over-expressers were reduced to 80% of those in wild type plants. Areas beneath stomata and patches lacking stomata were analysed separately. In areas without stomata, maximum fluorescence yield (Fv / Fm) and quantum yield of photosystem II (Φ PSII) were significantly lower than in areas beneath stomata. In areas beneath stomata, Fv / Fm and Φ PSII were identical to levels measured in wild type leaves. At high light intensities over-expressers showed decreased photochemical quenching (qP) compared with wild types. However, the decrease of qP was significantly stronger in areas without stomata than in mesophyll areas beneath stomata. At high CO2 partial pressures and high light intensities CO2 assimilation rates of SDD1 over-expressers did not reach wild type levels. These results indicate that photosynthesis in SDD1 over-expressers was reduced because of limiting CO2 in areas furthest from stomata at high light.

Changes in Levels of a-Tocopherol and Ascorbate in Spruce Needles at Three Low Mountain Sites Exposed to Mg2+-Deficiency and Ozone

1994 ◽  
Vol 49 (3-4) ◽  
pp. 171-180 ◽  
Author(s):  
U. Schmieden ◽  
A. Wild
Keyword(s):  
Oxidative Stress ◽  
Light Intensity ◽  
Chlorophyll A ◽  
Antioxidant Status ◽  
Photosynthetic Capacity ◽  
High Light Intensity ◽  
High Light ◽  
Absolute Level ◽  
Ozone Concentrations ◽  
Spruce Needles

The main objective of this study was the com parison of changes in levels of α-tocopherol and ascorbate in needles of spruce trees with various degrees of damage at three low mountain sites. The ascorbate content in needles of spruce trees with various degrees of dam age differs in the course of seasons as well as in the absolute level. The antioxidant status was affected mainly during summer. The content of ascorbate in needles of dam aged trees was significantly increased compared to that of undamaged trees. Despite seasonal and daily fluctuations, the level of ascorbate seems to be a good indicator for the degree of dam age in the case of symptoms described as montane yellowing. Together with an increasing content of α-tocopherol per chlorophyll, a rise of ascorbate content indicates enhanced oxidative stress in the needles of damaged trees, particularly in summer. Asc/αToc ratios were increased in needles of damaged trees. At the studied sites enhanced oxidative stress could be caused by the com bined action of Mg2+-deficiency, high ozone concentrations and high-light intensity, all inducing an increased production of radicals in combination with a reduced photosynthetic capacity

Response of abscisic acid mutants of Arabidopsis to salinity

2002 ◽  
Vol 29 (5) ◽  
pp. 561 ◽  
Author(s):  
Grant R. Cramer
Keyword(s):  
Abscisic Acid ◽  
Light Intensity ◽  
Salinity Stress ◽  
Root Elongation ◽  
High Salinity ◽  
Dry Weight ◽  
Protective Role ◽  
High Light Intensity ◽  
High Light ◽  
Total Dry Weight

Increases in abscisic acid (ABA) concentrations in plant tissues correlate with growth inhibition in salt-stressed plants. Therefore, it was hypothesized that Arabidopsis ABA mutants different in, or insensitive to, ABA would respond differently than wild type (wt) to salinity stress. Seeds (wt, abi1-1, abi2-1, abi3-1, and aba1-3) were germinated and grown hydroponically in three separate experiments with different environmental conditions: relative humidity at 80 or 100%, day/night temperatures at 21/18 or 23/20˚C, and light intensity at 125, 200 or 350 μmol photons m–2 s-1. Plants were exposed to salinity (either 0, 40 and 80 mM NaCl or 1, 5, and 9 dS m–1 with a Na/Ca ratio of 10 depending on the experiment) for one to several weeks before harvesting. The effect of salinity on root elongation rates of young seedlings was measured as well. Two-way ANOVA of root elongation rates of young seedlings and the growth of 3-week old plants in hydroponic solutions indicated that salinity inhibited growth, increased ABA and Na concentrations, and reduced K concentrations in all genotypes tested. However, there were no significant interactions with salinity and genotype for root elongation rates, total dry weight, shoot ABA and K concentrations. Shoot Na concentrations were significantly higher in wt plants relative to other genotypes subjected to high salinity stress. aba1-3 had significantly lower ABA concentrations than other genotypes, but the interaction of aba1-3 with salinity was the same as other genotypes. The lack of difference in interaction between genotype and salinity indicates that all genotypes responded in the same manner and amount to salinity for the particular parameter measured. Therefore, it appears that there are no significant differences in growth in response to salinity between the ABA mutants (ABA-deficient and ABA-insensitive) and wt. However, in contrast to the other genotypes, some of the ABA-deficient plants, aba1-3, died when exposed to high salinity and high light intensity. ABA appears to provide a protective role in conditions of high salinity and high light intensity.

The interplay between irrigation and fruiting on branch growth and mortality, gas exchange and water relations of coffee trees

2020 ◽  
Author(s):  
Wellington L Almeida ◽  
Rodrigo T Ávila ◽  
Junior P Pérez-Molina ◽  
Marcela L Barbosa ◽  
Dinorah M S Marçal ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Stomatal Density ◽  
Leaf Gas Exchange ◽  
Water Status ◽  
Co2 Concentration ◽  
Plant Hydraulics ◽  
Branch Growth ◽  
Source To Sink ◽  
Leaf Transpiration

Abstract The overall coordination between gas exchanges and plant hydraulics may be affected by soil water availability and source-to-sink relationships. Here we evaluated how branch growth and mortality, leaf gas exchange and metabolism are affected in coffee (Coffea arabica L.) trees by drought and fruiting. Field-grown plants were irrigated or not, and maintained with full or no fruit load. Under mild water deficit, irrigation per se did not significantly impact growth but markedly reduced branch mortality in fruiting trees, despite similar leaf assimilate pools and water status. Fruiting increased net photosynthetic rate in parallel with an enhanced stomatal conductance, particularly in irrigated plants. Mesophyll conductance and maximum RuBisCO carboxylation rate remained unchanged across treatments. The increased stomatal conductance in fruiting trees over nonfruiting ones was unrelated to internal CO2 concentration, foliar abscisic acid (ABA) levels or differential ABA sensitivity. However, stomatal conductance was associated with higher stomatal density, lower stomatal sensitivity to vapor pressure deficit, and higher leaf hydraulic conductance and capacitance. Increased leaf transpiration rate in fruiting trees was supported by coordinated alterations in plant hydraulics, which explained the maintenance of plant water status. Finally, by preventing branch mortality, irrigation can mitigate biennial production fluctuations and improve the sustainability of coffee plantations.

Stomatal Limitation of Photosynthesis in Abscisic Acid-Treated and in Water-Stressed Leaves Measured at Elevated CO2

1988 ◽  
Vol 15 (4) ◽  
pp. 495 ◽  
Author(s):  
SP Robinson ◽  
WJR Grant ◽  
BR Loveys
Keyword(s):  
Abscisic Acid ◽  
Stomatal Conductance ◽  
Quantum Yield ◽  
Oxygen Evolution ◽  
Stomatal Closure ◽  
Co2 Concentration ◽  
Assimilation Rate ◽  
High Co2 ◽  
Co2 Concentrations ◽  
Ambient Co2

Feeding 10-5M (�)-abscisic acid (ABA) via the petioles of detached leaves of apricot (Prunus armeniaca) or sunflower (Helianthus annuus) decreased stomatal conductance and assimilation rate but not the calculated intercellular CO2 concentration (Ci) suggesting non-stomatal as well as stomatal inhibition of photosynthesis. Evidence for non-stomatal inhibition was not observed in spinach (Spinacia oleracea). There was no significant decrease in rates of electron transport nor ribulosebisphosphate carboxylase (Rubisco) activity in intact chloroplasts isolated from ABA-treated sunflower leaves. Oxygen evolution by leaf discs with 3% CO2 in the gas phase was inhibited in ABA- treated sunflower and apricot leaves but not in spinach; the inhibition was only half as great as the inhibition of assimilation rate at ambient CO2. The quantum yield of oxygen evolution decreased in ABA-treated sunflower leaves in proportion to the decrease in the light-saturated rate. There was no significant difference in room temperature chlorophyll fluorescence of ABA-treated leaves compared to controls. Stomatal conductance of sunflower leaves decreased by more than 90% when the CO2 concentration was increased from 340 ppm to 1000 ppm but at much higher CO2 concentrations the stomata appeared to reopen. Stomatal conductance at 2-3% CO2 (20 000-30 000 ppm) was 50% that at ambient CO2. This reopening of stomata at high CO2 was inhibited in previously water-stressed or ABA-treated plants. In unstressed leaves, the maximum rate of oxygen evolution occurred at 0.5-2% CO2 but in ABA-treated leaves 10-15% CO2 was required for maximum rates. It is suggested that stomatal closure may limit photosynthesis in ABA-treated or previously water-stressed leaves even at the relatively high CO2 concentrations normally used in the leaf disc oxygen electrode. The inhibition of photosynthesis by ABA is largely overcome at saturating CO2. The apparent non-stomatal inhibition suggested by gas exchange measurements and the decreased quantum yield could be explained by patchy stomatal closure in response to ABA.

Effects of light intensity and CO2 concentration on the kinetics of 1st month growth and nitrogen fixation of alfalfa

1983 ◽  
Vol 61 (3) ◽  
pp. 731-740 ◽  
Author(s):  
F. D. H. Macdowall
Keyword(s):  
Light Intensity ◽  
Plant Growth ◽  
Rhizobium Meliloti ◽  
Net Photosynthesis ◽  
Co2 Concentration ◽  
Shoot Elongation ◽  
High Light Intensity ◽  
High Light ◽  
Low Light ◽  
Kinetics Of

Medicago sativa L. cv. Algonquin seedlings were grown for 28 days in growth rooms at several intensities of light and concentrations of CO2. Optimal or deficient NO3− concentrations were provided, the latter with or without inoculation and nodulation by Rhizobium meliloti str. 102F70 (Burton). All growth coefficients (k1′) were hyperbolically dependent on the intensity of light. Light saturation of plant k1′ was achieved, but the k1′ for nitrogenase development the highest in value, was not light saturated at high CO2 by the highest light intensity (555 μE∙m−2∙s−1). That intensity also did not saturate the photosynthesis of plants grown at that intensity nor the amount (yield) and absolute rate of plant growth. The latter were very much reduced at intensities below the compensation point (100 μE∙m−2∙s−1) of net photosynthesis. The data for k1′ at low light intensity indicated that photosynthate was utilized with equal efficiency for N2 and NO3− reduction. Fourfold enrichment of CO2 concentration did not influence the k1′ of plant growth in optimum NO3− and high light intensity but increased the yield by 78%. In the absence of high NO3− concentration, however, it nearly doubled the nitrogenase growth k1′, to a doubling time of 1.4 days, increased the nodule yield fourfold, the plant (symbiotic) yield threefold, and N content twofold. Sevenfold enrichment of CO2 was inhibitory to yields of N-deficient plants and nodules. The previous conclusion that added (combined) N chiefly limited seedling growth was supported by the lack of effect on plant k1′ of the stimulation of photosynthesis by high light intensity and CO2 concentration. A limitation on the value of the k1′ for shoot elongation in deficient combined N raised CO2 and high light was relieved symbiotically.

Sign in / Sign up

Export Citation Format

Share Document