scholarly journals Is amphistomy an adaptation to high light? Optimality models of stomatal traits along light gradients

2019 ◽  
Author(s):  
Christopher D. Muir
Keyword(s):  
Energy Budget ◽  
Water Loss ◽  
R Package ◽  
High Light ◽  
Carbon Gain ◽  
Marginal Effect ◽  
Costs And Benefits ◽  
Leaf Surfaces ◽  
Stomatal Traits ◽  
Optimality Models

AbstractStomata regulate the supply of CO2 for photosynthesis and the rate of water loss out of the leaf. The presence of stomata on both leaf surfaces, termed amphistomy, increases photosynthetic rate, is common in plants from high light habitats, and rare otherwise. In this study I use optimality models based on leaf energy budget and photosynthetic models to ask why amphistomy is common in high light habitats. I developed an R package leafoptimizer to solve for stomatal traits that optimally balance carbon gain with water loss in a given environment. The model predicts that amphistomy is common in high light because its marginal effect on carbon gain is greater than in the shade, but only if the costs of amphistomy are also lower under high light than in the shade. More generally, covariation between costs and benefits may explain why stomatal and other traits form discrete phenotypic clusters.

scholarly journals Is Amphistomy an Adaptation to High Light? Optimality Models of Stomatal Traits along Light Gradients

2019 ◽  
Vol 59 (3) ◽  
pp. 571-584 ◽  
Author(s):  
Christopher D Muir
Keyword(s):  
Energy Budget ◽  
Water Loss ◽  
R Package ◽  
High Light ◽  
Carbon Gain ◽  
Marginal Effect ◽  
Costs And Benefits ◽  
Leaf Surfaces ◽  
Stomatal Traits ◽  
Optimality Models

AbstractStomata regulate the supply of CO2 for photosynthesis and the rate of water loss out of the leaf. The presence of stomata on both leaf surfaces, termed amphistomy, increases photosynthetic rate, is common in plants from high light habitats, and rare otherwise. In this study I use optimality models based on leaf energy budget and photosynthetic models to ask why amphistomy is common in high light habitats. I developed an R package leafoptimizer to solve for stomatal traits that optimally balance carbon gain with water loss in a given environment. The model predicts that amphistomy is common in high light because its marginal effect on carbon gain is greater than in the shade, but only if the costs of amphistomy are also lower under high light than in the shade. More generally, covariation between costs and benefits may explain why stomatal and other traits form discrete phenotypic clusters.

scholarly journals Costs and benefits of photosynthetic stems in desert species from southern California

2019 ◽  
Vol 46 (2) ◽  
pp. 175 ◽  
Author(s):  
Eleinis Ávila-Lovera ◽  
Roxana Haro ◽  
Exequiel Ezcurra ◽  
Louis S. Santiago
Keyword(s):  
Isotopic Composition ◽  
Water Use Efficiency ◽  
Water Use ◽  
Water Loss ◽  
Water Status ◽  
Carbon Isotopic Composition ◽  
Carbon Gain ◽  
Costs And Benefits ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency

Woody plants with green photosynthetic stems are common in dry woodlands with the possible advantages of extra carbon gain, re-assimilation of CO2, and high water-use efficiency. However, their green stem tissue may also incur greater costs of water loss when stomata are closed. Our study focussed on evaluating the costs and benefits of having green stems in desert plants, addressing the water-use efficiency hypothesis. We measured water status, carbon and water exchange, and carbon, nitrogen and oxygen isotopic composition of 15 species in a desert wash scrub in Joshua Tree National Park, California, USA. We found that all woody species that have green stems relied on their green stems as the sole organ for carbon assimilation for most of the study period. Green stems had similar photosynthetic rate (Amax), stomatal conductance (gs) and intrinsic water-use efficiency (WUEi) to leaves of the same species. However, Amax, gs and cuticular conductance (gmin) were higher in green stems than in leaves of non-green stemmed species. Carbon isotopic composition (δ13C) was similar in both leaves and green stems, indicating no difference in integrated long-term WUE. Our results raise questions about the possible trade-off between carbon gain and water loss through the cuticle in green stems and how this may affect plant responses to current and future droughts.

Wood Density and Above-Ground Growth in High and Low Wood Density Clones of Pinus radiata D. Don

1990 ◽  
Vol 17 (6) ◽  
pp. 615 ◽  
Author(s):  
DW Sheriff ◽  
DA Rook
Keyword(s):  
Wood Density ◽  
Pinus Radiata ◽  
Light Treatment ◽  
High Light ◽  
The Other ◽  
Stem Volume ◽  
Carbon Gain ◽  
Simple Relationship ◽  
Ground Biomass ◽  
High Light Treatment

In Pinus radiata a negative relationship has usually been found between stem volume and wood density. Clones previously found to produce wood of high or low density were used to investigate interrelationships between above-ground partitioning coefficients, carbon gain, and wood density. Cuttings had been propagated c. 5 years earlier, and were 5 m high when the experiment started. Potential carbon gain of the tree was manipulated by using two light environments; one with a light level c. 1.5 times the other. Measurements were of changes in stem, branch, and needle biomass during the 305-day experiment, of rates of photosynthesis, and of wood density by β-ray densitometry and microscopy; densities determined by the two techniques were the same. For all but two trees, wood densities of a stem and its branches were the same; for the other two, stem density was 13% less than that of their branches. Trees in the high light treatment accumulated more above-ground biomass, but there was no simple relationship between wood density and either above-ground growth or photosynthesis. With one exception, partitioning of photosynthate to stem was constant. In most cases, proportionately less photosynthate (30-80%) was allocated to below-ground biomass in the low light treatment than in the high light treatment (60-80%).

An Energy Budget Approach to the Study of Water Loss in Cryptogams

1970 ◽  
Vol 97 (6) ◽  
pp. 361 ◽  
Author(s):  
George R. Hoffman ◽  
David M. Gates
Keyword(s):  
Energy Budget ◽  
Water Loss

scholarly journals Drought stress delays photosynthetic induction and accelerates photoinhibition of photosystem I under fluctuating light

2021 ◽  
Author(s):  
Hu Sun ◽  
Qi Shi ◽  
Ning-Yu Liu ◽  
Shi-Bao Zhang ◽  
Wei Huang
Keyword(s):  
Drought Stress ◽  
Gas Exchange ◽  
Photosystem I ◽  
Co2 Fixation ◽  
Electron Flow ◽  
Photosynthetic Performance ◽  
High Light ◽  
Carbon Gain ◽  
Photosynthetic Induction ◽  
Fluctuating Light

Fluctuating light (FL) and drought stress usually occur concomitantly. However, whether drought stress affects photosynthetic performance under FL remains unknown. Here, we measured gas exchange, chlorophyll fluorescence, and P700 redox state under FL in drought-stressed tomato (Solanum lycopersicum) seedlings. Drought stress significantly affected stomatal opening and mesophyll conductance after transition from low to high light and thus delayed photosynthetic induction under FL. Therefore, drought stress exacerbated the loss of carbon gain under FL. Furthermore, restriction of CO2 fixation under drought stress aggravated the over-reduction of photosystem I (PSI) upon transition from low to high light. The resulting stronger FL-induced PSI photoinhibition significantly supressed linear electron flow and PSI photoprotection. These results indicated that drought stress not only affected gas exchange under FL but also accelerated FL-induced photoinhibition of PSI. Furthermore, drought stress enhanced relative cyclic electron flow in FL, which partially compensated for restricted CO2 fixation and thus favored PSI photoprotection under FL. Therefore, drought stress has large effects on photosynthetic dark and light reactions under FL.

scholarly journals Drought stress delays photosynthetic induction and accelerates photoinhibition of photosystem I under fluctuating light

2021 ◽  
Author(s):  
Hu Sun ◽  
Qi Shi ◽  
Ning-Yu Liu ◽  
Shi-Bao Zhang ◽  
Wei Huang
Keyword(s):  
Drought Stress ◽  
Gas Exchange ◽  
Photosystem I ◽  
Co2 Fixation ◽  
Electron Flow ◽  
Photosynthetic Performance ◽  
High Light ◽  
Carbon Gain ◽  
Photosynthetic Induction ◽  
Fluctuating Light

Fluctuating light (FL) and drought stress usually occur concomitantly. However, whether drought stress affects photosynthetic performance under FL remains unknown. Here, we measured gas exchange, chlorophyll fluorescence, and P700 redox state under FL in drought-stressed tomato (Solanum lycopersicum) seedlings. Drought stress significantly affected stomatal opening and mesophyll conductance after transition from low to high light and thus delayed photosynthetic induction under FL. Therefore, drought stress exacerbated the loss of carbon gain under FL. Furthermore, restriction of CO2 fixation under drought stress aggravated the over-reduction of photosystem I (PSI) upon transition from low to high light. The resulting stronger FL-induced PSI photoinhibition significantly supressed linear electron flow and PSI photoprotection. These results indicated that drought stress not only affected gas exchange under FL but also accelerated FL-induced photoinhibition of PSI. Furthermore, drought stress enhanced relative cyclic electron flow in FL, which partially compensated for restricted CO2 fixation and thus favored PSI photoprotection under FL. Therefore, drought stress has large effects on photosynthetic dark and light reactions under FL.

The asynchronous response of carbon gain and water loss generate spatio-temporal pattern of WUE along elevation gradient in southwest China

2020 ◽  
Vol 581 ◽  
pp. 124389 ◽  
Author(s):  
Xiangyang Sun ◽  
Genxu Wang ◽  
Mei Huang ◽  
Ruiying Chang ◽  
Zhaoyong Hu ◽  
...  
Keyword(s):  
Water Loss ◽  
Temporal Pattern ◽  
Southwest China ◽  
Elevation Gradient ◽  
Carbon Gain ◽  
Spatio Temporal

scholarly journals Light-Mediated Signaling and Metabolic Changes Coordinate Stomatal Opening and Closure

2020 ◽  
Vol 11 ◽  
Author(s):  
Juan Yang ◽  
Chunlian Li ◽  
Dexin Kong ◽  
Fangyan Guo ◽  
Hongbin Wei
Keyword(s):  
Water Loss ◽  
Leaf Surface ◽  
Red Light ◽  
Stomatal Opening ◽  
Carbon Gain ◽  
Light Signaling ◽  
Dual Roles ◽  
Potential Applications ◽  
Use Efficiency ◽  
Signaling Components

Stomata are valves on the leaf surface controlling carbon dioxide (CO2) influx for photosynthesis and water loss by transpiration. Thus, plants have to evolve elaborate mechanisms controlling stomatal aperture to allow efficient photosynthesis while avoid excessive water loss. Light is not only the energy source for photosynthesis but also an important signal regulating stomatal movement during dark-to-light transition. Our knowledge concerning blue and red light signaling and light-induced metabolite changes that contribute to stomatal opening are accumulating. This review summarizes recent advances on the signaling components that lie between the perception of blue/red light and activation of the PM H+-ATPases, and on the negative regulation of stomatal opening by red light-activated phyB signaling and ultraviolet (UV-B and UV-A) irradiation. Besides, light-regulated guard cell (GC)-specific metabolic levels, mesophyll-derived sucrose, and CO2 concentration within GCs also play dual roles in stomatal opening. Thus, light-induced stomatal opening is tightly accompanied by brake mechanisms, allowing plants to coordinate carbon gain and water loss. Knowledge on the mechanisms regulating the trade-off between stomatal opening and closure may have potential applications toward generating superior crops with improved water use efficiency (CO2 gain vs. water loss).

Concurrent and lagged effects of spring greening on seasonal carbon gain and water loss across the Northern Hemisphere

2020 ◽  
Vol 64 (8) ◽  
pp. 1343-1354
Author(s):  
Jiaxin Jin ◽  
Fengsheng Guo ◽  
Sebastian Sippel ◽  
Qingsong Zhu ◽  
Weifeng Wang ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Water Loss ◽  
Carbon Gain ◽  
Lagged Effects

Plant Responses to Salinity Under Elevated Atmospheric Concentrations of CO2

1992 ◽  
Vol 40 (5) ◽  
pp. 515 ◽  
Author(s):  
MC Ball ◽  
R Munns
Keyword(s):  
Water Use Efficiency ◽  
Elevated Co2 ◽  
Water Use ◽  
Water Loss ◽  
Salt Flux ◽  
Carbon Gain ◽  
Salt Balance ◽  
Salt Uptake ◽  
Use Efficiency ◽  
Atmospheric Concentrations

This review explores effects of elevated CO2 concentrations on growth in relation to water use and salt balance of halophytic and non-halophytic species. Under saline conditions, the uptake and distribution of sodium and chloride must be regulated to protect sensitive metabolic sites from salt toxicity. Salt-tolerant species exclude most of the salt from the transpiration stream, but the salt flux from a highly saline soil is still considerable. To maintain internal ion concentrations within physiologically acceptable levels, the salt influx to leaves must match the capacities of leaves for salt storage and/or salt export by either retranslocation or secretion from glands. Hence the balance between carbon gain and the expenditure of water in association with salt uptake is critical to leaf longevity under saline conditions. Indeed, one of the striking features of halophytic vegetation, such as mangroves, is the maintenance of high water use efficiencies coupled with relatively low rates of water loss and growth. These low evaporation rates are further reduced under elevated CO2 conditions. This, with increased growth, leads to even higher water use efficiency. Leaves of plants grown under elevated CO2 conditions might be expected to contain lower salt concentrations than those grown under ambient CO2 if salt uptake is coupled with water uptake. However, salt concentrations in shoot tissues are similar in plants grown under ambient and elevated CO2 conditions despite major differences in water use efficiency. This phenomenon occurs in C3 halophytes and in both C3 and C2 non-halophytes. These results imply shoot/root communication in regulation of the salt balance to adjust to environmental factors affecting the availability of water and ions at the roots (salinity) and those affecting carbon gain in relation to water loss at the leaves (atmospheric concentrations of water vapour and carbon dioxide).

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