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1952. Coordinated variation between veins and stomata in cotton and its relationship with water-use efficiency under drought stress
- Creator:
- Lei, Z. Y., Han, J. M., Yi, X. P., Zhang, W. F., and Zhang, Y. L.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, major leaf veins, maximum stomatal conductance, minor leaf veins, stomata size, 2, and 581
- Language:
- Multiple languages
- Description:
- Drought stress causes changes in vein and stomatal density. The objectives of this study were to determine (1) if the changes in vein and stomatal density are coordinated in cotton (Gossypium hirsutum L.) and (2) how these changes affect water-use efficiency (WUE). The results showed significant positive correlations between vein density and stomatal density when cotton was grown under different degrees of drought stress. WUE was significantly positively correlated with the densities of both veins and stomata. Stomatal pore area and stomatal density on the abaxial leaf side, but not the adaxial side, were significantly correlated with WUE, stomatal conductance, leaf net photosynthetic rate, and transpiration rate. In conclusion, coordinated changes in vein and stomatal density improve the WUE of cotton under drought stress. The abaxial leaf side plays a more important role than the adaxial side in WUE and gas exchange., Z. Y. Lei, J. M. Han, X. P. Yi, W. F. Zhang, Y. L. Zhang., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1953. Copper binding sites associated with photosystem 2 preparations
- Creator:
- Barón, M., Arellano, J. B., Schroder, W., Lachica, M., and Chueca, A.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Some steps in the isolation method of photosystem 2 (PS2)-enriched partícles (BBY) influenced the Cu content of the finál preparation. In particular, the centrifugation at 10 000 X g ušed to remove starch after Triton X-100 treatment of the thylakoids, yielded starch-free BBY with a low copper content. This contrasted with the high Cu content of the starch-containing BBY. Differences in Cu levels of both preparations seemed thus to be related to the starch content of the sample. Four imidentifíed proteins were found in the starch fraction. They are probably new copper binding sites in the photosynthetic cell.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1954. Copper-mediated oxygen toxicity in rice chloroplasts
- Creator:
- Lidon, F.C. and Henriques, F.S.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Rice (Oryza sativa L.) plants were grown over a 30-d period in nutricnt soiution containing concentrations of Cu varying from 0.002 to 6.25 g iit^, and ihen oxygen toxicity was investigated in the chloroplasts. The Cu concentration in the shoots increased with increasing levels of this metal in the nutrient soiution, whereas the Fe concentration decreased after the 0.05 g m'^ Cu treatment and the Zn concentration did not show any clear tiend. Catalase, glutathione reductase and Cu,Zn-superoxide dismutase activities decreased with increasing Cu levels. On a fresh mass basis, ethylene production decreased after the 0.05 g Cu treatment, whereas, on a chlorophyll (Chl) basis, it increased until the 1.25 g m‘^ Cu iTeatment. The chloroplast lipid peroxidation increased (on a Chl and lipid basis) between the 0.01 and the 1.25 g m"^ Cu treatment. On a fresh mass basis the concentration of chloroplastic digalactosyldiacylglycerol, monogalactosyldiacylglycerol, phospha- tidylcholine, phosphatidylglycerol and phosphatidylinositol decreased, whereas, on a Chl basis, the concentration of the first two lipids sharply decreased after the 0.01 gm‘3 Cu treatment. Additionally, only a slight decrease was foiind in the concentration of phosphatidylglycerol with increasing Cu concentrations. Measurements of the linolenate hydroperoxide concentration in these acyl lipids showed an increase after the 0.01 g m'^ Cu treatment for the fnst two lipids as weil as an increase with increasing Cu levels for phosphatidylglycerol.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1955. Corrections to current approaches used to calculate energy partitioning in photosystem 2
- Creator:
- Kornyeyev, D. and Holaday, A. S.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Arabidopsis, chlorophyll fluorescence, Gossypium, lincomycin, Lycopersicon, mutant, PsbS protein, and thermal dissipation
- Language:
- Multiple languages
- Description:
- We analyzed several approaches dealing with the components of non-photochemical energy dissipation and introduced improved versions of the equations used to calculate this parameter. The usage of these formulae depends on the conditions of the sample (acclimation to dark or irradiation, presence or absence of the "actinic light"). The parameter known as "excess" cannot be used as a component of energy partitioning. In reality, this parameter reflects the differences between potential and actual quantum yields of photochemistry. and D. Kornyeyev, A. S. Holaday.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1956. Correlation between photoinhibition sensitivity and the rates and relative extents of xanthophyll cycle de-epoxidation in chlorina mutants of barley (Hordeum vulgare L.)
- Creator:
- Peng, Chang-Lian, Duan, Jun, Lin, Guizhu, and Gilmore, A. M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- antheraxanthin, chlorophyll a fluorescence, chlorosis, global kinetic analysis, non-photochemical quenching, photoprotection, violaxanthin, and zeaxanthin
- Language:
- Multiple languages
- Description:
- We compared photoinhibition sensitivity to high irradiance (HI) in wild-type barley (wt) and both its chlorina f104-nuclear gene mutant, that restricts chlorophyll (Chl) a and Chl b synthesis, and its f2-nuclear gene mutant, that inhibits all Chl b synthesis. Both Fv/Fm and ΦPS2 decreased more significantly in f2 than f104 and wt with duration of HI exposure. Chl degraded more rapidly in the f2 than in either f104 or wt. Most sensitivity to photoinhibition was exhibited for f2, whereas there was little difference in response to HI between the f104 and wt. The highest de-epoxidation (DES) value at every time point of exposure to HI was measured for f2, whereas the wt had the lowest value among the three strains. There were two lifetime components resolved for the conversion of violaxanthin (V) to zeaxanthin plus antheraxanthin (Z + A). The most rapid lifetime was around 6 min and the slower lifetime was >140 min, in both the mutants and wt. However, the wt and f104 both displayed larger amplitudes of both de-epoxidation lifetimes than f2. The difference between the final de-epoxidation state (DES = [Z + A]/[V + A + Z]) in the light compared to the dark expressed as ΔDES for wt, f104, and f2 was 0.630, 0.623, and 0.420, respectively. The slow lifetime component and overall larger ΔDES in the wt and f104 correlated with more photoprotection, as indicated by relatively higher Fv/Fm and ΦPS2, compared to the f2. Hence the photoprotection against photoinhibition has no relationship with the absolute DES value, but there is a strong relationship with de-epoxidation rate and relative extent or ΔDES. and Chang-Lian Peng ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1957. Correlation between some lipophilicity characteristics of morpholinoethylesters of 2-, 3- and 4-alkoxysubstituted phenylcarbamic acids, and their inhibitory activity in photosynthesizing organisms
- Creator:
- Králová, K., Loos, D., and Čižmárik, J.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Morphoiinoethylesters of 2-, 3- and 4-alkoxysubstituted phenylcarbamic acids (MAPC) inhibit photosynthetic processes in algae and plant chloroplasts. The inhibitoiy activity of MAPC in photosynthesizing organisms was in good correlations with lipophilicity characteristics such as hydrophobic fragment constants, partition coefficients and chromatographic retention factors.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1958. Corticular photosynthesis: A mechanism to enhance shrub expansion in coastal environments
- Creator:
- Vick, J. K. and Young, D. R.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- attenuation, barrier islands, chlorophyll, CO2, refixation, gross photosynthesis, respiration, and shrub expansion
- Language:
- Multiple languages
- Description:
- Myrica cerifera L. (Myricaceae), the dominant woody species on many barrier islands along the southeastern coast of the United States, is expanding into grass-dominated, mesic, interdunal depressions where it forms dense thickets. Expansion may be attributed to a symbiotic nitrogen fixation with the bacterium Frankia, an evergreen leaf habit and, possibly, corticular photosynthesis (CP, i.e. refixation of respired CO2, %ref). We quantified seasonal variations in CP characteristics in first through fifth order branches of M. cerifera to determine the extent and relevance of CP to shrub expansion in coastal environments. Maximum mean %ref was 110±39 % of CO2 efflux in the dark (RD) in first order branches during winter. Minimum %ref was 18±3 % in fifth order branches during summer. Variations in %ref paralleled changes in incident photosynthetic photon flux density (PPFD). As incident PPFD attenuated with increasing branch order, %ref decreased. A less dense canopy in winter led to increased PPFD and increases in %ref. Total chlorophyll (Chl) content and Chl a/b ratios were consistent with shade acclimation as branch order increased. CP may be a mechanism to enhance M. cerifera shrub expansion because of the potential increase in whole plant carbon use efficiency and water use efficiency attributed to refixation of respired CO2. and J. K. Vick, D. R. Young.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1959. Corylus avellana responsiveness to light variations: morphological, anatomical, and physiological leaf trait plasticity
- Creator:
- Catoni, R., Granata, M. U., Sartori, F., Varone, L., and Gratani, L.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, líska obecná, photosynthesis, Corylus avellana, Itálie, Italy, leaf area, leaf respiration, leaf thickness, photorespiration, 2, and 581
- Language:
- Multiple languages
- Description:
- Morphological, anatomical, and physiological leaf traits of Corylus avellana plants growing in different light conditions within the natural reserve "Siro Negri" (Italy) were analyzed. The results highlighted the capability of C. avellana to grow both in sun and shade conditions throughout several adaptations at leaf level. In particular, the more than 100% higher specific leaf area in shade is associated to a 44% lower palisade to spongy parenchyma thickness ratio compared with that in sun. Moreover, the chlorophyll (Chl) a to Chl b ratio decreased in response to the 97% decrease in photosynthetic photon flux density. The results highlighted the decrease in the ratio of Chl to carotenoid content, the maximum PSII photochemical efficiency, and the actual PSII photochemical efficiency (ΦPSII) associated with the increase in the ratio of photorespiration to net photosynthesis (PN) in sun. Chl a/b ratio was the most significant variable explaining PN variations in shade. In sun, PN was most influenced by the ratio between the fraction of electron transport rate (ETR) used for CO2 assimilation and ETR used for photorespiration, by ΦPSII, nitrogen content per leaf area, and by total Chl content per leaf area. The high phenotypic plasticity of C. avellana (PI = 0.33) shows its responsiveness to light variations. In particular, a greater plasticity of morphological (PIm = 0.41) than of physiological (PIp = 0.36) and anatomical traits (PIa = 0.24) attests to the shade tolerance of the species., R. Catoni, M.U. Granata, F. Sartori, L. Varone, L. Gratani., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1960. Cotton genotypic variation in the photosynthetic response to irradiance
- Creator:
- Pettigrew, W. T.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- area leaf mass, chlorophyll, dark respiration rate, Gossypium, leaf area, and protein
- Language:
- Multiple languages
- Description:
- The photosynthetic response of 8 cotton (Gossypium hirsutum L.) genotypes to changing irradiance was investigated under field conditions during the 1998 through 2000 growing seasons. Equations developed to describe the response of net photosynthetic rate (PN) to photosynthetic photon flux density (PPFD) demonstrated that, across all irradiances, the two okra leaf-type genotypes photosynthesized at a greater rate per unit leaf area than all of the six normal leaf-type genotypes. This superior photosynthetic performance of the okra leaf-type genotypes can be partially explained by their 13 % greater leaf chlorophyll content relative to that of the normal leaf-type genotypes. The 37 % reduction in leaf size brought upon by the okra leaf trait may have concentrated the amount of photosynthetic machinery per unit leaf area. Nevertheless, the lack of sufficient canopy leaf surface area suppressed the potential yield development that could accompany the higher PN per unit leaf area.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public