Mangrove Photosynthesis: Response to High-Irradiance Stress

1988 ◽  
Vol 15 (2) ◽  
pp. 43 ◽  
Author(s):  
O Bjorkman ◽  
B Demmig ◽  
TJ Andrews
Keyword(s):  
Energy Dissipation ◽  
Photosystem Ii ◽  
Energy Conversion ◽  
O2 Evolution ◽  
Photon Yield ◽  
Mangrove Species ◽  
Reaction Centres ◽  
Fluorescence Characteristics ◽  
Shade Leaves ◽  
Sun Leaves

Efficiencies of photosynthetic energy conversion were determined in sun and shade leaves of several mangrove species, growing in an open intertidal habitat in North Queensland, by measuring the maximum photon yield of O2 evolution and 77K chlorophyll fluorescence characteristics. Preliminary meas- urements confirmed that mangrove leaves have low water potentials, low stomatal conductances and low light-saturated CO2 exchange rates. Mangrove sun leaves therefore received a very large excess of excitation energy. Mangrove shade leaves had as high a photon yield of O2 evolution as non-mangrove leaves and their fluorescence characteristics were normal, showing that the energy conversion efficiency was unaffected by the high salinity. Mangrove sun leaves had markedly depressed photon yields and fluorescence was severely quenched showing that the efficiency of the photochemistry of photosystem II was reduced. The efficiency of energy conversion decreased with an increased radiation receipt. No such depression was detected in sun leaves of non-mangrove species growing in adjacent non-saline sites. Shading of man- grove sun leaves resulted in an increase in the efficiency of energy conversion but, in most species, more than 1 week was required for these leaves to reach the efficiency of shade leaves. Leaves exposed to direct sunlight had somewhat higher efficiencies in mangrove plants cultivated in 10% seawater as compared with full-strength seawater but the salinity of the culture solution had little effect on the increase in the efficiency upon shading. Field and laboratory fluorescence measurements indicated that the reduced efficiency of energy conversion in mangrove sun leaves resulted from a large increase in the rate constant for radiationless energy dissipation in the antenna chlorophyll rather than from damage to the photosystem II reaction centres. We propose that this increase in radiationless energy dissipation serves to protect the reaction centres against damage by excessive excitation.

Xanthophyll Cycle-Dependent Energy Dissipation and Flexible Photosystem II Efficiency in Plants Acclimated to Light Stress

1995 ◽  
Vol 22 (2) ◽  
pp. 249 ◽  
Author(s):  
B Demmig-Adams ◽  
WW Iii Adams ◽  
BA Logan ◽  
AS Verhoeven
Keyword(s):  
Energy Dissipation ◽  
Photosystem Ii ◽  
Xanthophyll Cycle ◽  
Light Stress ◽  
Photon Flux ◽  
Growth Environment ◽  
Psii Efficiency ◽  
Cycle Dependent ◽  
Shade Leaves ◽  
Sun Leaves

The effect of an acclimation to light stress during the growth of leaves on their response to high photon flux densities (PFDs) was characterised by quantifying changes in photosystem II (PSII) characteristics and carotenoid composition. During brief experimental exposures to high PFDs sun leaves exhibited: (a) much higher levels of antheraxanthin + zeaxanthin than shade leaves, (b) a greater extent of energy dissipation in the light-harvesting antennae, and (c) a greater decrease of intrinsic PSII efficiency that was rapidly reversible. During longer experimental exposures to high PFD, deep-shade leaves but not the sun leaves showed slowly developing secondary decreases in intrinsic PSII efficiency. Recovery of these secondary responses was also slow and inhibited by lincomycin, an inhibitor of chloroplast-encoded protein synthesis. In contrast, under field conditions all changes in intrinsic PSII efficiency in open sun-exposed habitats as well as understory sites with intense sunflecks appeared to be caused by xanthophyll cycle-dependent energy dissipation. Furthermore, comparison of leaves with different maximal rates of electron transport revealed that all leaves compensated fully for these differences by dissipating very different amounts of absorbed light via xanthophyll cycle-dependent energy dissipation, thereby all maintaining a similarly low PSII reduction state. It is our conclusion that an increased capacity for xanthophyll cycle-dependent energy dissipation is a key component of the acclimation of leaves to a variety of different forms of light stress, and that the response of leaves to excess light experienced in the growth environment is thus likely to be qualitatively different from that to sudden experimental exposures to PFDs exceeding the growth PFD.

Photosynthesis, quenching of chlorophyll fluorescence and thermal energy dissipation in iron-deficient sugar beet leaves

1998 ◽  
Vol 25 (4) ◽  
pp. 403 ◽  
Author(s):  
Fermín Morales ◽  
Anunciación Abadía ◽  
Javier Abadía
Keyword(s):  
Energy Dissipation ◽  
Iron Deficiency ◽  
Photosystem Ii ◽  
Sugar Beet ◽  
Electron Flow ◽  
Reaction Centers ◽  
O2 Evolution ◽  
Photosystem Ii Efficiency ◽  
Iron Deficient ◽  
Additional Support

In sugar beet (Beta vulgaris L.) iron deficiency decreased not only the photosynthetic rate but also the actual photosystem II efficiency at steady-state photosynthesis. In moderate iron deficiency, the decrease in actual photosystem II efficiency under illumination was related to closure of photosystem II reaction centers, whereas in severe iron deficiency it was associated to decreases of intrinsic photosystem II efficiency. The O2 evolution, on an absorbed light basis, decreased more than the actual photosystem II efficiency, suggesting the presence of a significant fraction of electron transport to molecular oxygen or the existence of some form of cyclic electron flow. Iron-deficient leaves reduced the excess of light absorbed that cannot be used in photosynthesis not only by decreasing absorptance, but also by dissipating a large part of the light absorbed by the photosystem II antenna. This mechanism, that protects the photosystem II reaction centers through the enhancement of energy dissipation, was related to the de-epoxidation of violaxanthin (V) to antheraxanthin (A) and zeaxanthin (Z) in iron-deficient leaves. These data provide additional support for a role of Z+A in photoprotection under conditions of excess photosynthetic light absorption.

Influence of CO2 and SO2 on Growth and Structure of Photosystem II of the Chinese Tung-Oil Tree Aleurites montana

1996 ◽  
Vol 51 (7-8) ◽  
pp. 441-453 ◽  
Author(s):  
P. He ◽  
A. Radunz ◽  
K. P. Bader ◽  
G. H. Schmid
Keyword(s):  
Photosystem Ii ◽  
Chlorophyll Content ◽  
Soluble Sugars ◽  
Soluble Proteins ◽  
Bisphosphate Carboxylase ◽  
Light Harvesting Complex ◽  
Sun And Shade Leaves ◽  
Sun And Shade ◽  
Shade Leaves ◽  
Sun Leaves

Three months old plants of the Chinese tung-oil tree Aleurites montana were cultivated for 4 months in air containing an increased amount of 700 ppm CO2. During the exposure to 700 ppm CO2 the plants exhibited a considerably stronger growth (30-40% ) in comparison to the control plants (grown in normal air). In these CO2-plants during the entire analyzing period the amount of soluble proteins, of soluble sugars and the chlorophyll content were lower than in control plants. The protein content, referred to leaf area, increased during this time in both plant types by approx. 50% but with a different time course. The increase is faster in CO2-plants compared to control plants, and ends up with similar values in both plants after 4 months. No difference is seen between sun and shade leaves. The chlorophyll content in both sun and shade leaves is 20% lower in CO2-plants. Whereas the chlorophyll content in sun leaves stays constant during developm ent, it has increased in shade leaves by 20% at the end of the 4 months period. The content of soluble sugars is lower in CO2-plants compared to control plants. The difference is bigger in sun leaves than in shade leaves. The ribulose 1.5-bisphosphate carboxylase/oxygenase content almost doubles within the experimentation period, but seems to be subject to large variations. CO2-plants contain in general less ribulose 1.5-bisphosphate carboxylase/oxygenase than control plants. The content of coupling factor of photophosphorylation is 20% lower in CO2-plants when compared to control plants and remains during development more constant in CO2-plants. The molecular structure of the photosystem II-complex undergoes under the influence of the increased CO2-content a quantitative modification. The light harvesting complex (LHCP) and the extrinsic peptide with the molecular mass of 33 kDa increase in CO2-plants. Gassing with SO2 (0.3 ppm in air) leads to a strong damage of the plants. The damaging influence is already seen after 6 days and leads to a partial leaf-shedding of the tree. In the visually still intact remaining leaves the chlorophyll content referred to unit leaf area decreases by 63%, that of soluble sugars by 65%, the content of soluble proteins and that of Rubisco decrease by 26% and 36% respectively. The light harvesting complex and the chlorophyll- binding peptides (43 and 47 kDa) increase whereas the extrinsic peptides decrease. It looks as if the simultaneous application of SO2 (0.3 ppm) and increased CO2 (700 ppm) releaves the damaging effect of SO2. Plant growth does not exhibit a difference in comparison to control plants. Soluble proteins and chlorophyll increase by 27% and 33% and the ribulose 1.5-bisphosphate carboxylase/oxygenase content as well as that of soluble sugars increases by 18 respectively 14%. The peptide composition of photosystem II shows a quantitative modification. The LHCP increases and the chlorophyll-binding peptides and the peptides with a molecular mass smaller than 24 kDa are reduced. The quantity of extrinsic peptides appears unchanged. Ribulose 1,5-bisphosphate carboxylase/oxygenase and the CF1-complex of Aleurites are immunochemically only partially identical to the corresponding enzymes of Nicotiana tabacum as demonstrated by tandem-cross-immune electrophoresis.

Vegetative and reproductive phenologies of four mangrove species from northern Australia

2005 ◽  
Vol 53 (2) ◽  
pp. 109 ◽  
Author(s):  
Grey T. Coupland ◽  
Eric I. Paling ◽  
Keith A. McGuinness
Keyword(s):  
Avicennia Marina ◽  
Leaf Longevity ◽  
Wet Season ◽  
Mangrove Species ◽  
Leaf Production ◽  
Rhizophora Stylosa ◽  
Large Variability ◽  
Leaf Flush ◽  
Shade Leaves ◽  
Sun Leaves

Mangrove communities in the tropical north of Australia are some of the most species rich in the world, yet surprisingly little is known of their reproductive and vegetative phenology. This study investigated the phenology of four mangrove species: Avicennia marina (Forsk.) Vierh., Ceriops australis (C.T.White) Ballment, T.J.Sm & Stoddart, Rhizophora stylosa Griff. and Sonneratia alba J.Smith, in Darwin Harbour over 24 months. Investigations included documenting the flowering and fruiting phenology, periods of leaf flush and leaf longevity. Flowering in these mangroves generally occurred during the dry season (June–October), with the exception of R. stylosa in which flowering occurred in the middle of the wet (December–February). Fruits and propagules were released in the dry and ‘build up’ periods (August–November), with the exception of A. marina, which released propagules in the middle of the wet season. Fruit and/or propagule maturation took less than 2 months in A. marina and S. alba, whereas in C. australis and R. stylosa maturation took 12 and 11 months, respectively. Timing of new leaf production generally coincided with the wet season, after the flowering and fruiting periods of each of the four species. Periods of leaf flush and leaf fall were often closely linked, and species with longer-lived leaves produced fewer leaves at each period of leaf flush. Maximum leaf longevity varied considerably among mangroves, ranging from 8 months in the lower canopy of S. alba to more than 24 months in C. australis. There was also large variability in leaf longevity among different regions of the canopy, with shade leaves generally living longer than sun leaves, and leaves in the upper canopy (3–7 m) longer than those in the lower regions (0–3 m).

Effect of Canopy Position on the Susceptibility of Kiwifruit (Actinidia deliciosa) Leaves on Vines in an Orchard Environment to Photoinhibition Throughout the Growing Season

1995 ◽  
Vol 22 (2) ◽  
pp. 299 ◽  
Author(s):  
DH Greer
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosynthetic Capacity ◽  
Growing Season ◽  
Actinidia Deliciosa ◽  
Photon Flux ◽  
Photon Yield ◽  
Canopy Position ◽  
Shade Leaves ◽  
Sun Leaves ◽  
The Impact

Kiwifruit (Actinidia deliciosa (A. Chev) C.F. Liang & A.R. Ferguson) plants grown in an orchard were studied over several seasons to assess the impact of photoinhibition on the leaves using chlorophyll fluorescence and photosynthetic measurements. Leaves above were compared with those below the vine canopy. In addition, temperature and photon flux densities above and below the canopy were monitored. A gradient of sun to shade photosynthetic characteristics developed in leaves from above to below the canopy. There was a 10% higher Fv/Fm ratio in the shade leaves (0.810) but a 30% lower photosynthetic capacity and a 30% higher photon yield than in sun leaves. In addition, Fo and Fm were both higher (20-60%) in shade leaves. Little variation in Fv/Fm occurred throughout the growing season, except during spring, when Fv/Fm was about 0.4-0.5, especially in small, rapidly expanding leaves. Changes in Fv/Fm during spring were correlated with leaf diameter, indicating development of photosynthetic competence was an important factor in the rise in Fv/Fm. However, increasing night temperatures also correlated with the increase in Fv/Fm during spring.

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