The Effect of Chloramphenicol on Photoinhibition of Photosynthesis and Its Recovery in Intact Kiwifruit (Actinidia deliciosa) Leaves

1993 ◽  
Vol 20 (1) ◽  
pp. 33 ◽  
Author(s):  
DH Greer ◽  
WA Laing ◽  
DJ Woolley

Photoinhibition of photosynthesis in kiwifruit [Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson] leaves in high light and its subsequent recovery in low light was assessed in the presence of chloramphenicol (CAP), an inhibitor of chloroplast-encoded protein synthesis. Rooted cuttings were grown in a controlled environment at a photosynthetic irradiance of 700 μmol m-2 s-1 and a day/night temperature of 25/20�C. Time-courses of photoinhibition and recovery treatments were followed by measuring CO2 exchange and chlorophyll fluorescence at 77K and 692 nm. CAP both exacerbated photoinhibition and blocked recovery for at least 150 min, especially at high temperatures. The close conformation of these two effects affirm that photoinhibition and recovery occur concomitantly. There was no apparent effect of CAP on the xanthophyll cycle, either during photoinhibition or recovery, indicating that zeaxanthin-mediated non-radiative energy (thermal) dissipation was unaffected by CAP. Because the CAP-induced increase in photoinhibition was not matched by an increase in the ratio of zeaxanthin to violaxanthin and antheraxanthin, the capacity of this photoprotective mechanism was apparently saturated. The primary effect of CAP on chlorophyll fluorescence was to affect Fm, the maximum fluorescence. There was only a minor effect on the initial fluorescence, Fo, during the photoinhibition and recovery treatments. The calculation of the rate constants for non-radiative dissipation (kD) and photochemistry (kp) from the fluorescence measurements indicated that an increase in kD occurred during high-light exposures and this was stimulated by CAP. However, since zeaxanthin was not mediating this, an alternative quencher in kiwifruit leaves, perhaps damaged PSII centres, is proposed. This would be consistent with an increased inactivation of PSII, as indicated by the changes in kp.

1988 ◽  
Vol 15 (2) ◽  
pp. 195 ◽  
Author(s):  
DH Greer

Photoinhibition of photosynthesis was induced in intact leaves of kiwifruit (Actinidia deliciosa) grown in natural light not exceeding a photon irradiance (PI) of 300 �mol m-2 s-1 by exposing them to a PI of 1500 �mol m-2 s-1. The temperature was held constant during the high-light exposure between 5 and 35°C. Recovery was followed at temperatures between 10 and 35°C, after photoinhibition was induced by a 240 min exposure to high light. The kinetics of photoinhibition and recovery were followed by chlorophyll fluorescence at 692 nm and 77K. Photoinhibition occurred at all temperatures but was greatest at low temperatures. Temperature affected the severity of photoinhibitory damage but not the kinetics of photoinhibition. Recovery was also temperature-dependent with little or no recovery occurring below about 20°C and rapid recovery at 30-35°C. The extent of photoinhibition also affected the rates of recovery which were reduced as the severity of photoinhibition increased. An analysis of the rate constants for energy transfer within photosystem II indicated that kiwifruit leaves have some capacity to prevent photoinhibition by increasing the amount of non-radiative energy dissipation. However, the analysis also indicates that this protection mechanism was not wholly effective since the primary photochemical reactions apparently become inactivated during exposure of these leaves to high light.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 541a-541
Author(s):  
Lailiang Cheng ◽  
Leslie H. Fuchigami ◽  
Patrick J. Breen

Bench-grafted Fuji/M26 apple trees were fertigated with different concentrations of nitrogen by using a modified Hoagland solution for 6 weeks, resulting in a range of leaf N from 1.0 to 4.3 g·m–2. Over this range, leaf absorptance increased curvilinearly from 75% to 92.5%. Under high light conditions (1500 (mol·m–2·s–1), the amount of absorbed light in excess of that required to saturate CO2 assimilation decreased with increasing leaf N. Chlorophyll fluorescence measurements revealed that the maximum photosystem II (PSII) efficiency of dark-adapted leaves was relatively constant over the leaf N range except for a slight drop at the lower end. As leaf N increased, non-photochemical quenching under high light declined and there was a corresponding increase in the efficiency with which the absorbed photons were delivered to open PSII centers. Photochemical quenching coefficient decreased significantly at the lower end of the leaf N range. Actual PSII efficiency increased curvilinearly with increasing leaf N, and was highly correlated with light-saturated CO2 assimilation. The fraction of absorbed light potentially used for free radical formation was estimated to be about 10% regardless of the leaf N status. It was concluded that increased thermal dissipation protected leaves from photo-oxidation as leaf N declined.


2020 ◽  
Author(s):  
Peiqi Yang ◽  
Christiaan Van der Tol ◽  
Petya K. E. Campbell ◽  
Elizabeth M. Middleton

Abstract. Estimates of the gross terrestrial carbon uptake exhibit large uncertainties. Sun-induced chlorophyll fluorescence (SIF) has an apparent near-linear relationship with gross primary production (GPP). This relationship will potentially facilitate the monitoring of photosynthesis from space. However, the exact mechanistic connection between SIF and GPP is still not clear. To explore the physical and physiological basis for their relationship, we used a unique dataset comprising continuous field measurements of leaf and canopy fluorescence and photosynthesis of corn over a growing season. We found that, at canopy scale, the positive relationship between SIF and GPP was dominated by absorbed photosynthetically active radiation (APAR), which was equally affected by variations in incoming radiation and changes in canopy structure. After statistically controlling these underlying physical effects, the remaining correlation between far-red SIF and GPP due solely to the functional link between fluorescence and photosynthesis at the photochemical level was much weaker. Active leaf-level fluorescence measurements revealed a moderate correlation between the efficiencies of fluorescence emission and photochemistry for sunlit leaves but a weak correlation for shaded leaves. Differentiating sunlit and shaded leaves in the light use efficiency (LUE) models for SIF and GPP facilitates a better understanding of the SIF-GPP relationship at different environmental and canopy conditions. Leaf-level fluorescence measurements also demonstrated that the sustained thermal dissipation efficiency dominated the seasonal energy partitioning while the reversible heat dissipation dominated the diurnal leaf energy partitioning. These diurnal and seasonal variations in heat dissipation underlie, and are thus responsible for, the observed remote sensing-based link between far-red SIF and GPP.  


2021 ◽  
Vol 18 (2) ◽  
pp. 441-465
Author(s):  
Peiqi Yang ◽  
Christiaan van der Tol ◽  
Petya K. E. Campbell ◽  
Elizabeth M. Middleton

Abstract. Estimates of the gross terrestrial carbon uptake exhibit large uncertainties. Sun-induced chlorophyll fluorescence (SIF) has an apparent near-linear relationship with gross primary production (GPP). This relationship will potentially facilitate the monitoring of photosynthesis from space. However, the exact mechanistic connection between SIF and GPP is still not clear. To explore the physical and physiological basis for their relationship, we used a unique data set comprising continuous field measurements of leaf and canopy fluorescence and photosynthesis of corn over a growing season. We found that, at canopy scale, the positive relationship between SIF and GPP was dominated by absorbed photosynthetically active radiation (APAR), which was equally affected by variations in incoming radiation and changes in canopy structure. After statistically controlling these underlying physical effects, the remaining correlation between far-red SIF and GPP due solely to the functional link between fluorescence and photosynthesis at the photochemical level was much weaker (ρ=0.30). Active leaf level fluorescence measurements revealed a moderate positive correlation between the efficiencies of fluorescence emission and photochemistry for sunlit leaves in well-illuminated conditions but a weak negative correlation in the low-light condition, which was negligible for shaded leaves. Differentiating sunlit and shaded leaves in the light use efficiency (LUE) models for SIF and GPP facilitates a better understanding of the SIF–GPP relationship at different environmental and canopy conditions. Leaf level fluorescence measurements also demonstrated that the sustained thermal dissipation efficiency dominated the seasonal energy partitioning, while the reversible heat dissipation dominated the diurnal leaf energy partitioning. These diurnal and seasonal variations in heat dissipation underlie, and are thus responsible for, the observed remote-sensing-based link between far-red SIF and GPP.


Chlorophyll fluorescence induction (at 20 °C and 77 K) and quenching were analysed in relation to effects of environmental stresses imposed by chilling in high light and by freezing and thawing of spinach ( Spinacia oleracea L.) leaves. The data indicate that cold acclimation of spinach plants, which leads to increased frost tolerance of the leaves, results in decreased susceptibility to photoinhibition of photosynthesis at chilling temperatures. When plants acclimated to 18 °C and 260-300 µmol quanta m -2 s -1 were exposed to higher light (550 µmol quanta m -2 s -1 ) at 4 °C, they developed strong photoinhibition, as characterized by decreased quantum yield of O 2 evolution and decreased ratio of variable: maximum fluorescence (F V /F M ) of photosystem II. The decrease in F V /F M resulted from a decline in F V and an increase in F 0 . The F V /F M ratio was lowered to a significantly greater extent when induction was recorded at 20 °C, as compared with 77 K. The effects related to photoinhibition were fully reversible at 18 °C in dim light. Plants that had been cold-acclimated for 10 days exhibited slightly decreased quantum yield and lowered F V /F M ratio. However, they did not show further photoinhibition on exposure to 550 µmol quanta m -2 s -1 at 4 °C. The reversible photoinhibition is discussed as a protective pathway serving for thermal dissipation of excessive light energy. It is hypothesized that such a mechanism prevents destruction of the photosynthetic apparatus, until other means of protection become effective during long-term acclimation to high light. Inhibition of photosynthetic carbon assimilation caused by freezing and thawing of leaves in the dark was closely correlated with inhibition of photochemical fluorescence quenching (q Q ). As a sensitive response of the thylakoid membranes to freezing stress, the energy-dependent quenching, q E , was inhibited. Only more severe impact of freezing caused a significant decline in the F V /F M ratio. It is concluded that measurements of fluorescence induction signals ( F V /F M ratios) provide a sensitive tool with which to investigate photoinhibition, whereas freezing damage to the photosynthetic system can be detected more readily by the quenching coefficients q Q and q E than by F V /F M ratios.


2010 ◽  
Vol 37 (5) ◽  
pp. 395 ◽  
Author(s):  
Roland Pieruschka ◽  
Denis Klimov ◽  
Zbigniew S. Kolber ◽  
Joseph A. Berry

Chlorophyll fluorescence measurements have been widely applied to quantify the photosynthetic efficiency of plants non-destructively. The most commonly used pulse amplitude modulated (PAM) technique provides a saturating light pulse, which is not practical at the canopy scale. We report here on a recently developed technique, laser induced fluorescence transient (LIFT), which is capable of remotely measuring the photosynthetic efficiency of selected leaves at a distance of up to 50 m. The LIFT approach correlated well with gas exchange measurements under laboratory conditions and was tested in a field experiment monitoring the combined effect of low temperatures and high light intensity on a variety of plants during the early winter in California. We observed a reduction in maximum and effective quantum yield in electron transport for Capsicum annuum L., Lycopersicon esculentum L. and Persea americana Mill. as the temperatures fell, while a grass community was not affected by combined low temperature and high light stress. The ability to make continuous, automatic and remote measurements of the photosynthetic efficiency of leaves with the LIFT system provides a new approach for studying and monitoring of stress effects on the canopy scale.


2021 ◽  
Vol 68 (3) ◽  
pp. 510-518
Author(s):  
Y. F. Hao ◽  
Y. Y. Feng ◽  
L. J. Cai ◽  
Qiong Wu ◽  
L. L. Song

2000 ◽  
Vol 78 (8) ◽  
pp. 1021-1033 ◽  
Author(s):  
Ann Marie Odasz-Albrigtsen ◽  
Hans Tømmervik ◽  
Patrick Murphy

Photosynthetic efficiency was estimated by chlorophyll fluorescence measurements (Fv/Fm) in 11 plant species growing along a steep gradient of airborne pollution along the Russian-Norwegian border (70°N, 30°E). Photosynthetic efficiency was positively correlated with environmental variables including annual temperature and a maritime gradient and was negatively correlated with the airborne concentrations of Cu, Ni, and SO2 from the Cu-Ni smelters. Photosynthetic efficiency in six plant species from the mixed forest, but not pine (Pinus sylvestris L.), and three species from the birch forest was inversely correlated with SO2 and the concentrations of Ni and Cu in lichens. Measurement of fluorescence in these species was a sensitive indicator of pollutant impact. Plant cover at the 16 study sites and the photosynthetic efficiency of five target species correlated with normalized difference vegetation index (NDVI) values. This study demonstrated that it is possible to detect relations among field-measured ecophysiological responses in plants, levels of airborne pollutants, and satellite remote-sensed data.Key words: chlorophyll fluorescence, smelters, sulfur dioxide, nickel, copper, normalized difference vegetation index (NDVI).


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