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1603. Life time deficiency of photosynthetic pigment-protein complexes CP1, A1, AB1, and AB2 in two cecidomyiid galls derived from Machilus thunbergii leaves

Creator:
Yang, C. M., Yang, M. M., Huang, M. Y., Hsu, J. M., and Jane, W. N.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll, chloroplast, immunoblotting, leaf age, and ultrastructure
Language:
Multiple languages
Description:
Two kinds of cecidomyiid galls induced by Daphnephila on Machilus thunbergii Sieb. & Zucc. leaves at various developmental stages, i.e., young, growing, and mature, were analyzed for their biochemical composition of photosynthetic pigment-protein complexes located in thylakoid membranes using the Thornber and MARS electrophoretic fractionation systems. Both kinds of galls were totally deficient in the pigment-protein complexes CP1, and A1, AB1, and AB2 through the whole period of gall formation. Immunoblotting of antibody against light-harvesting complex 2b (LHC2b) apoprotein confirmed this deficiency in gall's lifetime, which never recovered under any condition. Electron microscopy demonstrated that already at the early developmental stage the gall chloroplasts had thylakoid morphology like that in a normal leaf. and C. M. Yang ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1604. Light absorption and competition in mixed communities of Hordeum leporinum-Euphorbia scordifolia

Creator:
Khadr, F. G. M. A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
dry mass, leaf area index, leaf temperature, net photosynthetic rate, plant density, stomatal conductance, and transpiration
Language:
Multiple languages
Description:
The effect of Euphorbia scordifolia and Hordeum leporinum competition on leaf area development, radiant energy absorption, and dry matter production was evaluated in a field experiment. Profile measurements (0-0.3, 0.3-0.6, 0.6-0.9, and >0.9 m above ground) of absorbed photosynthetically active radiation (APAR) and leaf area index (LAI) by species were taken at four densities of E. scordifolia (0, 1, 4, and 12 plants per m2). APAR calculated for H. leporinum in mixed communities was 79, 77, and 49 % of the APAR in H. leporinum and LAI was reduced to 81, 65, and 37 %. LAI of H. leporinum was concentrated in the 0.3-0.6 m layer, while the taller E. scordifolia plants had the greatest LAI above 0.6 m. By absorbing radiant energy in the upper canopy, E. scordifolia reduced APAR penetrating to H. leporinum. Measurements of net photosynthetic and transpiration rates, leaf temperature, and stomatal conductance confirmed the importance of competition for PAR for plant growth and metabolism.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1605. Light acclimation at the end of the growing season in two broadleaved oak species

Creator:
Cano, F. J., Sánchez-Gómez, D., Gascó, A., Rodríguez-Calcerrada, J., Gil, L., Warren, C. R., and Aranda, I.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, hydraulic conductivity, internal conductance, light acclimation, mature leaves, Quercus petraea, and Quercus pyrenaica
Language:
Multiple languages
Description:
The ability of plants to increase their net CO2 assimilation rate in response to increased irradiance is due to morphological and physiological changes, which might be related to their shade tolerance and leaf ontogeny, but few studies have considered morphology and physiology. Two sympatric oak species (the shade-tolerant Q. petraea and the comparatively shade-intolerant Q. pyrenaica) were grown in hydroponic solution in low-light (LL) and high-light (HL) conditions. 5 months after leaf expansion under these conditions, half of the LL plants were transferred to high light (TLH). Transfer of Q. pyrenaica, from low- to high light led to photoinhibition and after 21 days in higher light there was little acclimation of the maximum rate of carboxylation (VCmax) or the maximum rate of electron transport (Jmax). Q. pyrenaica TLH plants showed lower stomatal conductance at all times compared to plants growing in LL. Stomatal closure was the main limitation to photosynthesis after transfer in Q. pyrenaica. The increase in evaporative demand upon TLH did not affect hydraulic conductivity of Q. pyrenaica. In contrast, the more shade-tolerant Q. petraea showed a greater degree of acclimation of gas exchange in TLH than Q. pyrenaica and two weeks after transfer gas-exchange rates were as high as in LL plants. In Q. petraea, the most important changes occurred at the level of leaf biochemistry with significant increase in VCmax that decreased the Jmax/VCmax ratio below values recorded in HL plants. However, this potential increase in photosynthesis was at least partially hamstrung by a decrease in internal conductance, which highlights the importance of internal conductance in acclimation to higher light in mature leaves. Neither oak species reached the photosynthetic rates of HL plants; however a trend towards leaf acclimation was observed in Q. petraea while the transfer was harmful to the leaves of Q. pyrenaica developed in the shade. and F. J. Cano ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1606. Light availability and soil flooding regulate photosynthesis of an imperiled shrub in lowland forests of the Mississippi Alluvial Valley, USA

Creator:
Lockhart, B. R., Gardiner, E. S., Leininger, T. D., Devall, M. S., Wilson, A. D., Connor, K. F., Hamel, P. B., and Schiff, N. M.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
plasticita, plasticity, Mississippi, oblast čepele listu, interakce, blade area, blade mass, interaction, pondberries, 2, and 581
Language:
Multiple languages
Description:
Physiological responses to light availability and soil flooding on Lindera melissifolia (Walt.) Blume were studied. Shrubs were grown under 70, 37 or 5% of full sunlight with either 0, 45, or 90 d of soil flooding. We measured leaf photosynthetic rate (PN) to test the hypothesis that soil flooding reduces PN in L. melissifolia following shrub acclimation to low light availability. Results showed that light availability and soil flooding interacted to affect PN. In the 0 d and 45 d flooding regimes (flood water removed 36-39 d prior to measurement), PN was similar between shrubs receiving 70% or 37% light, and these shrubs had 147% greater PN than shrubs receiving 5% light. Shrubs receiving 90 d of soil flooding had similar low rates of area-based PN regardless of light level. Similar PN between 0 d and 45 d flooded shrubs indicated physiological recovery following removal of flood water., B. R. Lockhart, E. S. Gardiner, T. D. Leininger, M. S. Devall, A. D. Wilson, K. F. Connor, P. B. Hamel, N. M. Schiff., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1607. Light dependence of carboxylation capacity for C3 photosynthesis models

Creator:
Bunce, J. A.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
oxid uhličitý, teplota, fazole, carbon dioxide, temperature, beans, změna klimatu, climate change, modeling, C3, CO2, quinoa, elektronová doprava, mezibuněčná koncentrace CO2, list, common bean, electron transport, intercellular CO2 concentration, leaf, 2, and 581
Language:
Multiple languages
Description:
C3 photosynthesis at high light is often modeled by assuming limitation by the maximum capacity of Rubisco carboxylation (VCmax) at low CO2 concentrations, by electron transport capacity (Jmax) at higher CO2 concentrations, and sometimes by triose-phosphate utilization rate at the highest CO2 concentrations. Net photosynthetic rate (PN) at lower light is often modeled simply by assuming that it becomes limited by electron transport (J). However, it is known that Rubisco can become deactivated at less than saturating light, and it is possible that PN at low light could be limited by the rate of Rubisco carboxylation (VC) rather than J. This could have important consequences for responses of PN to CO2 and temperature at low light. In this work, PN responses to CO2 concentration of common bean, quinoa, and soybean leaves measured over a wide range of temperatures and PPFDs were compared with rates modeled assuming either VC or J limitation at limiting light. In all cases, observed rates of PN were better predicted by assuming limitation by VC rather than J at limiting light both below and above the current ambient CO2. One manifestation of this plant response was that the relative stimulation of PN with increasing the ambient CO2 concentration from 380 to 570 µmol mol-1 did not decrease at less than saturating PPFDs. The ratio of VC to VCmax at each lower PPFD varied linearly with the ratio of PN at low PPFD to PN at high PPFD measured at 380 µmol(CO2) mol-1 in all cases. This modification of the standard C3 biochemical model was much better at reproducing observed responses of light-limited PN to CO2 concentrations from pre-industrial to projected future atmospheric concentrations., J. A. Bunce., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1608. Light distribution in leaf chambers and its consequences for photosynthesis measurements

Creator:
Hogewoning, S. W., Trouwborst, G., Harbinson, J., and van Ieperen, W.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, gas exchange, heterogeneity, leaf chamber, light distribution, photosynthesis, and photosynthetic quantum yield
Language:
Multiple languages
Description:
The impact of a heterogeneous distribution of actinic light within a leaf chamber for photosynthetic measurements by gas exchange on the photosynthesis-irradiance relationship was investigated. High-resolution light distributions were measured over the area of a commercially available clamp-on leaf chamber equipped with build-in red and blue LEDs, as well as over the area of a custom-made leaf chamber with external light source, using a low-cost digital camera and freely available software. The impact of the measured heterogeneity on the photosynthesis-irradiance response curve was calculated for two realistic scenarios. When the average light intensity over the leaf chamber area was estimated accurately, heterogeneity had minor effects on the photosynthesis-irradiance response curve. However, when the irradiance was measured in the chamber centre, which is common practice, and assumed to be homogeneous, for both leaf chambers the photosynthesis-irradiance response curve was subject to considerable error and led to serious underestimation of the light-limited quantum yield of photosynthesis. Additionally, mixed light sources with different heterogeneity patterns per light source, such as in the clamp-on leaf chamber, potentially increase errors due to heterogeneous physiological responses to light spectrum. High-resolution quantification of the leaf-chamber light distribution enables calculation of the correct average light intensity and already resolves the most pressing problems associated with heterogeneity. To exclude any light-distribution related errors in gas-exchange measurements a leaf chamber and actinic irradiance source design with a homogeneous light distribution is an absolute requirement. and S. W. Hogewoning ...[et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1609. Light induced aerobic degradation of Dl/D2/cyt b559 preparations from spinach analysed by low temperature spectroscopy

Creator:
Maciy, K., Voigt, J., and Renger, R.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
The radiant energy induced degradation at 293 K of isolated Dl/D2/cyt b559 complexes from spinách was investigated under aerobic conditions by measurements of absorption and emission spectra between 1.1 and 270 K. In the 1.1 K absorption spectrum a bleaching and slight blue shift at 679 nm and a blue shift of the 672 nm band was observed. In the emission spectrum deconvoluted into Gaussian bands, the major fluorescence band referred to as F682 was most susceptible to photodegradation: (7) At all temperatures F682 was blue shifted with respect to the control. (2) The half-width of F682 was temperature independent at T < 10 K and became significantly increased in damaged samples. (3) The temperature dependence of rp6g2 in the range of 10 K < T < 270 K was less pronounced in damaged samples. Our results support the idea of a multistep model of photodegradation with several intermediates in the pathway from the undamaged control into strongly damaged complexes. The temperature dependence of rp6g2 i® explained by contributions owing to static and dynamical inhomogeneous broadening. The static inhomogeneous broadening increases with progressing degradation. Furthermore, our results suggest that aerobic photodegradation of the Dl/D2/cyt 3559 complexes also causes modifications of the electron-phonon interactions. The frequency of the phonon mode dominating the electron phonon coupling decreases in damaged samples.
Rights:
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1610. Light induction of nonphotochemical quenching, CO2 fixation, and photoinhibition in woody and fern species adapted to different light regimes

Creator:
Wong, S.-L., Huang, M.-Y., Chen, C.-W., and Weng, J.-H.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, light adaptation, NPQ, photoinhibition, photosynthetic induction, photosynthetic rate, 2, and 581
Language:
Multiple languages
Description:
We aimed to find out relations among nonphotochemical quenching (NPQ), gross photosynthetic rate (PG), and photoinhibition during photosynthetic light induction in three woody species (one pioneer tree and two understory shrubs) and four ferns adapted to different light regimes. Pot-grown plants received 100% and/or 10% sunlight according to their light-adaptation capabilities. After at least four months of light acclimation, CO2 exchange and chlorophyll fluorescence were measured simultaneously in the laboratory. We found that during light induction the formation and relaxation of the transient NPQ was closely related to light intensity, light-adaption capability of species, and PG. NPQ with all treatments increased rapidly within the first 1-2 min of the light induction. Thereafter, only species with high PG and electron transport rate (ETR), i.e., one pioneer tree and one mild shade-adapted fern, showed NPQ relaxing rapidly to a low steady-state level within 6-8 min under PPFD of 100 μmol(photon) m-2 s-1 and ambient CO2 concentration. Leaves with low PG and ETR, regardless of species characteristics or inhibition by low CO2 concentration, showed slow or none NPQ relaxation up to 20 min after the start of low light induction. In contrast, NPQ increased slowly to a steady state (one pioneer tree) or it did not reach the steady state (the others) from 2 to 30 min under PPFD of 2,000 μmol m-2 s-1. Under high excess of light energy, species adapted to or plants acclimated to high light exhibited high NPQ at the initial 1 or 2 min, and showed low photoinhibition after 30 min of light induction. The value of fastest-developing NPQ can be quickly and easily obtained and might be useful for physiological studies., S.-L. Wong, M.-Y. Huang, C.-W. Chen, J.-H. Weng., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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