Greenhouse and field cucumber genotypes use different mechanisms to protect against dark chilling

2004 ◽  
Vol 31 (12) ◽  
pp. 1215 ◽  
Author(s):  
Yan-Hong Zhou ◽  
Li-Feng Huang ◽  
Yao-Shun Du ◽  
Jing-Quan Yu
Keyword(s):  
Calvin Cycle ◽  
Photosynthetic Electron Transport ◽  
Co2 Assimilation ◽  
Photochemical Quenching ◽  
Genotypic Differences ◽  
Diurnal Changes ◽  
Cucumis Sativus L ◽  
Photosynthetic Gas Exchange ◽  
Protection Mechanism ◽  
Psii Photochemistry

Diurnal changes in photosynthetic gas exchange and chlorophyll fluorescence were measured after two consecutive night chills to reveal the photosynthetic characteristics and the mechanism of photoprotection in a greenhouse genotype Jinyou No. 3 (GH), and in a field genotype Jinyan No. 4 (OF) of cucumber (Cucumis sativus L.). Both genotypes showed inhibition of CO2 assimilation immediately after the dark chill, with OF exhibiting a greater reduction. Dark chilling had little effect on stomatal limitation (l) and RuBP regeneration (Jmax) but significantly decreased maximum carboxylation velocity of Rubisco (Vcmax). The reduced capacity for CO2 fixation in the Calvin cycle induced a downstream regulation of PSII photochemistry, a mechanism that regulates the photosynthetic electron transport to match the lower demand for ATP and NADPH in the stroma of chloroplasts. The reduced quantum efficiency of PSII photochemistry was mainly due to reductions both in the photochemical quenching coefficient (qP) and in the efficiency of excitation energy capture by open PSII reaction centres (Fv′ / Fm′) for OF, but only to the latter for GH. Night chills resulted in an enhanced photorespiration proportion in GH and an O2-dependent alternative electron flux in OF, which served as protective mechanisms for the two varieties. These results showed that there are genotypic differences in the limitation factor for CO2 assimilation and in photo-protection mechanism to night chill in cucumber.

scholarly journals Far-Red Light Accelerates Photosynthesis in the Low-Light Phases of Fluctuating Light

2019 ◽  
Vol 61 (1) ◽  
pp. 192-202 ◽  
Author(s):  
Masaru Kono ◽  
Hikaru Kawaguchi ◽  
Naoki Mizusawa ◽  
Wataru Yamori ◽  
Yoshihiro Suzuki ◽  
...  
Keyword(s):  
Red Light ◽  
Atp Synthesis ◽  
Co2 Assimilation ◽  
Photosynthetic Performance ◽  
Antenna System ◽  
Photochemical Quenching ◽  
Low Light ◽  
Yield Increase ◽  
Fluctuating Light ◽  
Psii Photochemistry

Abstract It is well known that far-red light (FR; >700 nm) drives PSI photochemistry, but its effect on photosynthetic performance has received little attention. In this study, the effects of the addition of FR to red fluctuating light (FL) have on photosynthesis were examined in the leaves of Arabidopsis thaliana. Light-activated leaves were illuminated with FL [alternating high light/low light (HL/LL) at 800/30 μmol m−2 s−1] for 10–15 min without or with FR at intensities that reflected natural conditions. The CO2 assimilation rates upon the transition from HL to LL were significantly greater with FR than without FR. The enhancement of photosynthesis by FR was small under the steady-state conditions and in the HL phases of FL. Proton conductivity through the thylakoid membrane (gH+) in the LL phases of FL, estimated from the dark relaxation kinetics of the electrochromic absorbance shift, was greater with FR than without FR. The relaxation of non-photochemical quenching (NPQ) in the PSII antenna system and the increase in PSII photochemistry in the LL phases accelerated in the presence of FR. Similar FR-effects in FL were confirmed in typical sun and shade plants. On the basis of these results, we concluded that FR exerted beneficial effects on photosynthesis in FL by exciting PSI and accelerating NPQ relaxation and PSII-yield increase. This was probably because of the increased gH+, which would reflect faster ΔpH dissipation and ATP synthesis.

Factors affecting CO2 assimilation, leaf injury and growth in salt-stressed durum wheat

2002 ◽  
Vol 29 (12) ◽  
pp. 1393 ◽  
Author(s):  
Richard A. James ◽  
Anna Rita Rivelli ◽  
Rana Munns ◽  
Susanne von Caemmerer
Keyword(s):  
Water Relations ◽  
Tetraploid Wheat ◽  
Co2 Assimilation ◽  
Shoot Biomass ◽  
Genotypic Differences ◽  
Leaf Injury ◽  
Factors Affecting ◽  
Thermal Energy Dissipation ◽  
Psii Photochemistry ◽  
Stomatal Limitations

To examine the factors that affect tolerance to high internal salt concentrations, two tetraploid wheat genotypes that differ in the degree of salt-induced leaf injury (Wollaroi and Line 455) were grown in 150 mM NaCl for 4 weeks. Shoot biomass of both genotypes was substantially reduced by salinity, but genotypic differences appeared only after 3 weeks, when durum cultivar Wollaroi showed greater leaf injury and a greater reduction in biomass than Line 455. Ion accumulation, water relations, chlorophyll fluorescence and gas exchange were followed on one leaf (leaf 3) throughout its life. Salinity caused a large decrease in stomatal conductance (gs) of both genotypes. This was not due to poor water relations, as leaf turgor of both genotypes was higher in the salt treatment than in controls, so chemical signals were likely to have caused the decrease in gs. Reductions in assimilation rate were initially due to gs and, with time, were due to a combination of stomatal and non-stomatal limitations. The non-stomatal limitations were associated with a build up of Na+ above 250 mM. The efficiency of PSII photochemistry in Line 455 was unaffected throughout. However, in Wollaroi, the potential and actual quantum yield of PSII photochemistry began to decline as the leaf aged and the thermal energy dissipation of excess light energy (NPQ) increased. This coincided with high Na+ and Cl– concentrations in the leaf and with chlorophyll degradation, indicating that these later reductions in CO2 assimilation in Wollaroi were a consequence of a direct toxic ion effect. The earlier reduction in CO2 assimilation and greater leaf injury explain why growth of Wollaroi was less than Line 455. The most sensitive indicator of salinity stress was gs, followed by CO2 assimilation, with fluorescence parameters other than NPQ being no more sensitive than chlorophyll itself.

Characterisation of Three Components of Non-photochemical Fluorescence Quenching and Their Response to Photoinhibition

1988 ◽  
Vol 15 (2) ◽  
pp. 163 ◽  
Author(s):  
B Demmig ◽  
K Winter
Keyword(s):  
Fluorescence Quenching ◽  
Heat Dissipation ◽  
Photosynthetic Electron Transport ◽  
Co2 Assimilation ◽  
Nerium Oleander ◽  
Photochemical Quenching ◽  
Ps Ii ◽  
Fluorescence Characteristics ◽  
Non Photochemical Quenching ◽  
Three Components

Three components of non-photochemical fluorescence quenching were distinguished according to their response to irradiance and to their relaxation kinetics upon darkening. Two components of quenching were restricted to excessive irradiance and were interpreted to reflect radiationless dissipation. One relaxed rapidly upon darkening, and increased sharply when irradiance became excessive, i.e. as soon as net CO2 assimilation rate was no longer linearly related to irradiance, and attained a maximum value with only small further increases in irradiance. The second component relaxed slowly, increased mark- edly when the rapidly relaxing component had reached its maximum, and continued to increase linearly with increasing irradiance. The third component was already present at low irradiances, relaxed very slowly, and may be related to an altered distribution of excitation energy between PS II and PS I. Following exposure to weak illumination under conditions preventing photosynthetic electron transport (20 mbar O2, zero CO2), the reduction state of Q was initially high and decreased as non- photochemical fluorescence quenching indicative of radiationless dissipation developed. Subsequent to photoinhibitory treatments in high light and 20 mbar O2, zero CO2, an increased reduction state of Q as well as increased non-photochemical quenching of the two types indicative of increased heat dissipation was observed. In sunflower a lasting increase in the reduction state of Q was observed and fluorescence characteristics reflected photoinhibitory damage. In Nerium oleander, increased radiationless dissipation of the slowly relaxing type was the predominant response and the reduction state of Q was increased only transiently.

scholarly journals Size-dependent susceptibility of lake phytoplankton to light stress: An implication for succession of large green algae in a deep oligotrophic lake

2021 ◽  
Author(s):  
Takehiro Kazama ◽  
Kazuhide Hayakawa ◽  
Takamaru Nagata ◽  
Koichi Shimotori ◽  
Akio Imai ◽  
...  
Keyword(s):  
Algal Blooms ◽  
Light Stress ◽  
Photochemical Efficiency ◽  
Early Summer ◽  
Photochemical Quenching ◽  
P Deficiency ◽  
Chl A ◽  
Psii Photochemistry ◽  
Small Phytoplankton ◽  
Nutrient Bioassay

Field observations of the population dynamics and measurements of photophysiology in Lake Biwa were conducted by size class (< vs. > 30 μm) from early summer to autumn to investigate the relationships between susceptibility to light stress and cell size. Also, a nutrient bioassay was conducted to clarify whether the growth rate and photosystem II (PSII) photochemistry of small and large phytoplankton are limited by nutrient availability. Large phytoplankton, which have lower intracellular Chl-a concentrations, had higher maximum PSII photochemical efficiency (Fv/Fm) but lower non-photochemical quenching (NPQNSV) than small phytoplankton under both dark and increased light conditions. The nutrient bioassay revealed that the PSII photochemistry of small phytoplankton was restricted by N and P deficiency at the pelagic site even at the end of the stratification period, while that of large phytoplankton was not. These results suggest that large phytoplankton have lower susceptibility to PSII photodamage than small phytoplankton due to lower intracellular Chl-a concentrations. The size dependency of susceptibility to PSII photoinactivation may play a key role in large algal blooms in oligotrophic water.

scholarly journals Assessment of Heat-tolerance Potential in QTL Introgressed Lines of Hybrid Rice Restorer, KMR-3R through PS-II Efficiency

2021 ◽  
pp. 258-266
Author(s):  
V. Jaldhani ◽  
D. Sanjeeva Rao ◽  
P. Beulah ◽  
B. Srikanth ◽  
P. R. Rao ◽  
...  
Keyword(s):  
High Temperature ◽  
Quantum Yield ◽  
Temperature Stress ◽  
Heat Tolerance ◽  
Photosynthetic Apparatus ◽  
High Temperature Stress ◽  
Maximum Efficiency ◽  
Photochemical Quenching ◽  
Psii Photochemistry ◽  
Heat Tolerant

Aims: To assess heat-induced PSII damage and efficiency in eight promising backcross introgression lines (BC2F6) of KMR-3R/N22 possessing qHTSF1.1 and qHTSF4.1. Study Design:  Randomized Complete Block Design (RCBD) with three replications. Place and Duration of Study: ICAR-Indian Institute of Rice Research, Hyderabad India during wet/rainy (Kharif) season 2018. Methodology: Eight ILs (BC2F6) and parents were evaluated for heat tolerance. The high- temperature stress was imposed by enclosing the crop with a poly cover tent (Polyhouse) just before the anthesis stage. The fluorescence parameters viz., maximum efficiency of PSII photochemistry (Fv/Fm), Electron transport rate (ETR), effective PSII quantum yield (ΦPSII), coefficient of photochemical quenching (qP) and coefficient of non-photochemical quenching (qN) were measured under ambient and high-temperature stress. Results: The heat-tolerance potential of ILs was assessed in terms of PSII activity. The results indicated that significant differences were observed between treatments (T), genotypes (G) and the interaction between T × G.  The physiological basis of introgressed QTLs controls the spikelet fertility by maintaining the productive and adaptive strategies in heat-tolerant QTL introgressed lines with stable photosynthetic apparatus (PSII) under high-temperature stress. Conclusion: The Fv/Fm ratio denotes the maximum quantum yield of PSII. The heat-tolerant QTL introgressed lines exhibited stable photosynthetic apparatus (PSII) and noted better performance under high-temperature stress. They may be used as donors for fluorescence traits in breeding rice for high-temperature tolerance.

Stomatal aperture can compensate altered stomatal density in Arabidopsis thaliana at growth light conditions

2006 ◽  
Vol 33 (11) ◽  
pp. 1037 ◽  
Author(s):  
Dirk Büssis ◽  
Uritza von Groll ◽  
Joachim Fisahn ◽  
Thomas Altmann
Keyword(s):  
Arabidopsis Thaliana ◽  
Stomatal Conductance ◽  
Stomatal Density ◽  
Co2 Assimilation ◽  
High Light ◽  
Stomatal Aperture ◽  
Photochemical Quenching ◽  
Light Conditions ◽  
Wild Type ◽  
Light Intensities

Stomatal density of transgenic Arabidopsis thaliana plants over-expressing the SDD1 (stomatal density and distribution) gene was reduced to 40% and in the sdd1-1 mutant increased to 300% of the wild type. CO2 assimilation rate and stomatal conductance of over-expressers and the sdd1-1 mutant were unchanged compared with wild types when measured under the light conditions the plants were exposed to during growth. Lower stomatal density was compensated for by increased stomatal aperture and conversely, increased stomatal density was compensated for by reduced stomatal aperture. At high light intensities the assimilation rates and stomatal conductance of SDD1 over-expressers were reduced to 80% of those in wild type plants. Areas beneath stomata and patches lacking stomata were analysed separately. In areas without stomata, maximum fluorescence yield (Fv / Fm) and quantum yield of photosystem II (Φ PSII) were significantly lower than in areas beneath stomata. In areas beneath stomata, Fv / Fm and Φ PSII were identical to levels measured in wild type leaves. At high light intensities over-expressers showed decreased photochemical quenching (qP) compared with wild types. However, the decrease of qP was significantly stronger in areas without stomata than in mesophyll areas beneath stomata. At high CO2 partial pressures and high light intensities CO2 assimilation rates of SDD1 over-expressers did not reach wild type levels. These results indicate that photosynthesis in SDD1 over-expressers was reduced because of limiting CO2 in areas furthest from stomata at high light.

A simple dynamic model of photosynthesis in oak leaves: coupling leaf conductance and photosynthetic carbon fixation by a variable intracellular CO2 pool

2004 ◽  
Vol 31 (12) ◽  
pp. 1195 ◽  
Author(s):  
Steffen M. Noe ◽  
Christoph Giersch
Keyword(s):  
Carbon Fixation ◽  
Calvin Cycle ◽  
Target Function ◽  
Vapour Pressure Deficit ◽  
Co2 Assimilation ◽  
Leaf Conductance ◽  
Co2 Partial Pressure ◽  
Sink Term ◽  
Essential Components ◽  
Oak Leaves

Modelling the diurnal course of photosynthesis in oak leaves (Quercus robur L.) requires appropriate description of the dynamics of leaf photosynthesis of which diurnal variations in leaf conductance and in CO2 assimilation are essential components. We propose and analyse a simple photosynthesis model with three variables: leaf conductance (gs), the CO2 partial pressure inside the leaf (pi), and a pool of Calvin cycle intermediates (aps). The environmental factors light (I) and vapour pressure deficit (VPD) are used to formulate a target function G(I, VPD) from which the actual leaf conductance is calculated. Using this gs value and a CO2 consumption term representing CO2 fixation, a differential equation for pi is derived. Carboxylation corresponds to the sink term of the pi pool and is assumed to be feedback-inhibited by aps. This simple model is shown to produce reasonable to excellent fits to data on the diurnal time courses of photosythesis, pi and gs sampled for oak leaves.

An intrinsically disordered protein, CP12: jack of all trades and master of the Calvin cycle

2012 ◽  
Vol 40 (5) ◽  
pp. 995-999 ◽  
Author(s):  
Brigitte Gontero ◽  
Stephen C. Maberly
Keyword(s):  
Amino Acids ◽  
Stress Responses ◽  
Intrinsically Disordered Proteins ◽  
Calvin Cycle ◽  
Intrinsically Disordered Protein ◽  
Disulfide Bridge ◽  
Co2 Assimilation ◽  
Disordered Proteins ◽  
Dimensional Structure ◽  
Intrinsically Disordered

Many proteins contain disordered regions under physiological conditions and lack specific three-dimensional structure. These are referred to as IDPs (intrinsically disordered proteins). CP12 is a chloroplast protein of approximately 80 amino acids and has a molecular mass of approximately 8.2–8.5 kDa. It is enriched in charged amino acids and has a small number of hydrophobic residues. It has a high proportion of disorder-promoting residues, but has at least two (often four) cysteine residues forming one (or two) disulfide bridge(s) under oxidizing conditions that confers some order. However, CP12 behaves like an IDP. It appears to be universally distributed in oxygenic photosynthetic organisms and has recently been detected in a cyanophage. The best studied role of CP12 is its regulation of the Calvin cycle responsible for CO2 assimilation. Oxidized CP12 forms a supramolecular complex with two key Calvin cycle enzymes, GAPDH (glyceraldehyde-3-phosphate dehydrogenase) and PRK (phosphoribulokinase), down-regulating their activity. Association–dissociation of this complex, induced by the redox state of CP12, allows the Calvin cycle to be inactive in the dark and active in the light. CP12 is promiscuous and interacts with other enzymes such as aldolase and malate dehydrogenase. It also plays other roles in plant metabolism such as protecting GAPDH from inactivation and scavenging metal ions such as copper and nickel, and it is also linked to stress responses. Thus CP12 seems to be involved in many functions in photosynthetic cells and behaves like a jack of all trades as well as being a master of the Calvin cycle.

scholarly journals The chaperonin 60 protein SlCpn60α1 modulates photosynthesis and photorespiration in tomato

2020 ◽  
Vol 71 (22) ◽  
pp. 7224-7240
Author(s):  
Jie Ye ◽  
Weifang Chen ◽  
Longwei Feng ◽  
Genzhong Liu ◽  
Ying Wang ◽  
...  
Keyword(s):  
Calvin Cycle ◽  
Photosynthetic Electron Transport ◽  
Single Copy ◽  
Chlorophyll Synthesis ◽  
Insertion Mutant ◽  
Loss Of Function ◽  
Virus Induced Gene Silencing ◽  
Dna Insertion ◽  
Dimensional Electrophoresis ◽  
Two Hybrid

Abstract Photosynthesis, an indispensable biological process of plants, produces organic substances for plant growth, during which photorespiration occurs to oxidize carbohydrates to achieve homeostasis. Although the molecular mechanism underlying photosynthesis and photorespiration has been widely explored, the crosstalk between the two processes remains largely unknown. In this study, we isolated and characterized a T-DNA insertion mutant of tomato (Solanum lycopersicum) named yellow leaf (yl) with yellowish leaves, retarded growth, and chloroplast collapse that hampered both photosynthesis and photorespiration. Genetic and expression analyses demonstrated that the phenotype of yl was caused by a loss-of-function mutation resulting from a single-copy T-DNA insertion in chaperonin 60α1 (SlCPN60α1). SlCPN60α1 showed high expression levels in leaves and was located in both chloroplasts and mitochondria. Silencing of SlCPN60α1using virus-induced gene silencing and RNA interference mimicked the phenotype of yl. Results of two-dimensional electrophoresis and yeast two-hybrid assays suggest that SlCPN60α1 potentially interacts with proteins that are involved in chlorophyll synthesis, photosynthetic electron transport, and the Calvin cycle, and further affect photosynthesis. Moreover, SlCPN60α1 directly interacted with serine hydroxymethyltransferase (SlSHMT1) in mitochondria, thereby regulating photorespiration in tomato. This study outlines the importance of SlCPN60α1 for both photosynthesis and photorespiration, and provides molecular insights towards plant genetic improvement.

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