scholarly journals High Carotenoid Mutants of Chlorella vulgaris Show Enhanced Biomass Yield under High Irradiance

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 911
Author(s):  
Zeno Guardini ◽  
Luca Dall’Osto ◽  
Simone Barera ◽  
Mehrdad Jaberi ◽  
Stefano Cazzaniga ◽  
...  
Keyword(s):  
Chlorella Vulgaris ◽  
Biomass Conversion ◽  
Light Stress ◽  
Carbon Assimilation ◽  
Carotenoid Biosynthesis ◽  
High Irradiance ◽  
Chemical Mutagenesis ◽  
Photooxidative Stress ◽  
Promising Target ◽  
Excess Light

Microalgae represent a carbon-neutral source of bulk biomass, for extraction of high-value compounds and production of renewable fuels. Due to their high metabolic activity and reproduction rates, species of the genus Chlorella are highly productive when cultivated in photobioreactors. However, wild-type strains show biological limitations making algal bioproducts expensive compared to those extracted from other feedstocks. Such constraints include inhomogeneous light distribution due to high optical density of the culture, and photoinhibition of the surface-exposed cells. Thus, the domestication of algal strains for industry makes it increasingly important to select traits aimed at enhancing light-use efficiency while withstanding excess light stress. Carotenoids have a crucial role in protecting against photooxidative damage and, thus, represent a promising target for algal domestication. We applied chemical mutagenesis to Chlorella vulgaris and selected for enhanced tolerance to the carotenoid biosynthesis inhibitor norflurazon. The NFR (norflurazon-resistant) strains showed an increased carotenoid pool size and enhanced tolerance towards photooxidative stress. Growth under excess light revealed an improved carbon assimilation rate of NFR strains with respect to WT. We conclude that domestication of Chlorella vulgaris, by optimizing both carotenoid/chlorophyll ratio and resistance to photooxidative stress, boosted light-to-biomass conversion efficiency under high light conditions typical of photobioreactors. Comparison with strains previously reported for enhanced tolerance to singlet oxygen, reveals that ROS resistance in Chlorella is promoted by at least two independent mechanisms, only one of which is carotenoid-dependent.

scholarly journals Combined resistance to oxidative stress and reduced antenna size enhance light-to-biomass conversion efficiency in Chlorella vulgaris cultures

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Luca Dall’Osto ◽  
Stefano Cazzaniga ◽  
Zeno Guardini ◽  
Simone Barera ◽  
Manuel Benedetti ◽  
...  
Keyword(s):  
Chlorella Vulgaris ◽  
Fossil Fuels ◽  
Biomass Conversion ◽  
Carbon Assimilation ◽  
Phenotypic Selection ◽  
Biofuel Production ◽  
Carbon Assimilation Rate ◽  
Photon Conversion ◽  
Pale Green ◽  
Fast Growth Rate

Abstract Background Microalgae are efficient producers of lipid-rich biomass, making them a key component in developing a sustainable energy source, and an alternative to fossil fuels. Chlorella species are of special interest because of their fast growth rate in photobioreactors. However, biological constraints still cast a significant gap between the high cost of biofuel and cheap oil, thus hampering perspective of producing CO2-neutral biofuels. A key issue is the inefficient use of light caused by its uneven distribution in the culture that generates photoinhibition of the surface-exposed cells and darkening of the inner layers. Efficient biofuel production, thus, requires domestication, including traits which reduce optical density of cultures and enhance photoprotection. Results We applied two steps of mutagenesis and phenotypic selection to the microalga Chlorella vulgaris. First, a pale-green mutant (PG-14) was selected, with a 50% reduction of both chlorophyll content per cell and LHCII complement per PSII, with respect to WT. PG-14 showed a 30% increased photon conversion into biomass efficiency vs. WT. A second step of mutagenesis of PG-14, followed by selection for higher tolerance to Rose Bengal, led to the isolation of pale-green genotypes, exhibiting higher resistance to singlet oxygen (strains SOR). Growth in photobioreactors under high light conditions showed an enhanced biomass production of SOR strains with respect to PG-14. When compared to WT strain, biomass yield of the pale green + sor genotype was enhanced by 68%. Conclusions Domestication of microalgae like Chlorella vulgaris, by optimizing both light distribution and ROS resistance, yielded an enhanced carbon assimilation rate in photobioreactor.

scholarly journals A chloroplast thylakoid lumen protein is required for proper photosynthetic acclimation of plants under fluctuating light environments

2017 ◽  
Vol 114 (38) ◽  
pp. E8110-E8117 ◽  
Author(s):  
Jun Liu ◽  
Robert L. Last
Keyword(s):  
Photosystem Ii ◽  
Light Stress ◽  
High Irradiance ◽  
Light Conditions ◽  
Agricultural Plant ◽  
Photosynthetic Organisms ◽  
Fluctuating Light ◽  
Stress Susceptibility ◽  
Efficiency And Productivity ◽  
Photosynthetic Adaptation

Despite our increasingly sophisticated understanding of mechanisms ensuring efficient photosynthesis under laboratory-controlled light conditions, less is known about the regulation of photosynthesis under fluctuating light. This is important because—in nature—photosynthetic organisms experience rapid and extreme changes in sunlight, potentially causing deleterious effects on photosynthetic efficiency and productivity. Here we report that the chloroplast thylakoid lumenal protein MAINTENANCE OF PHOTOSYSTEM II UNDER HIGH LIGHT 2 (MPH2; encoded byAt4g02530) is required for growth acclimation ofArabidopsis thalianaplants under controlled photoinhibitory light and fluctuating light environments. Evidence is presented thatmph2mutant light stress susceptibility results from a defect in photosystem II (PSII) repair, and our results are consistent with the hypothesis that MPH2 is involved in disassembling monomeric complexes during regeneration of dimeric functional PSII supercomplexes. Moreover,mph2—and previously characterized PSII repair-defective mutants—exhibited reduced growth under fluctuating light conditions, while PSII photoprotection-impaired mutants did not. These findings suggest that repair is not only required for PSII maintenance under static high-irradiance light conditions but is also a regulatory mechanism facilitating photosynthetic adaptation under fluctuating light environments. This work has implications for improvement of agricultural plant productivity through engineering PSII repair.

Does Astaxanthin Protect Haematococcus against Light Damage?

1998 ◽  
Vol 53 (1-2) ◽  
pp. 93-100 ◽  
Author(s):  
Lu Fan ◽  
Avigad Vonshak ◽  
Aliza Zarka ◽  
Sammy Boussiba
Keyword(s):  
Light Intensity ◽  
Light Stress ◽  
Phosphate Starvation ◽  
High Light Intensity ◽  
High Irradiance ◽  
High Light ◽  
Protective Agent ◽  
Light Damage ◽  
Low Light ◽  
Very High

Abstract The photoprotective function of the ketocarotenoid astaxanthin in Haematococcus was questioned. When exposed to high irradiance and/or nutritional stress, green Haematococcus cells turned red due to accumulation of an immense quantity of the red pigment astaxanthin. Our results demonstrate that: 1) The addition of diphenylamine, an inhibitor of astaxanthin biosynthesis, causes cell death under high light intensity; 2) Red cells are susceptible to high light stress to the same extent or even higher then green ones upon exposure to a very high light intensity (4000 μmol photon m-2 s-1); 3) Addition of 1O2 generators (methylene blue, rose bengal) under noninductive conditions (low light of 100 (μmol photon m-2 s-1) induced astaxanthin accumulation. This can be reversed by an exogenous 1O2 quencher (histidine); 4) Histidine can prevent the accumulation of astaxanthin induced by phosphate starvation. We suggest that: 1) Astaxanthin is the result of the photoprotection process rather than the protective agent; 2) 1O2 is involved indirectly in astaxanthin accumulation process.

Photosynthetic Electron Transport Regulates the Expression of Cytosolic Ascorbate Peroxidase Genes in Arabidopsis during Excess Light Stress

1997 ◽  
Vol 9 (4) ◽  
pp. 627 ◽  
Author(s):  
Stanislaw Karpinski ◽  
Carolina Escobar ◽  
Barbara Karpinska ◽  
Gary Creissen ◽  
Philip M. Mullineaux
Keyword(s):  
Electron Transport ◽  
Ascorbate Peroxidase ◽  
Light Stress ◽  
Photosynthetic Electron Transport ◽  
Cytosolic Ascorbate Peroxidase ◽  
Excess Light

scholarly journals Role of hydrogen peroxide and the redox state of ascorbate in the induction of antioxidant enzymes in pea leaves under excess light stress

2004 ◽  
Vol 31 (4) ◽  
pp. 359 ◽  
Author(s):  
Jose A. Hernández ◽  
Carolina Escobar ◽  
Gary Creissen ◽  
Phil M. Mullineaux
Keyword(s):  
Antioxidant Enzymes ◽  
Redox State ◽  
Light Stress ◽  
Redox Status ◽  
Protein Accumulation ◽  
Photoinhibition Of Photosynthesis ◽  
Transcript Accumulation ◽  
Land Race ◽  
Excess Light

In this work we used two different pea cultivars, JI281 is a semidomesticated land race of pea from Ethiopia whereas JI399 is a typical domesticated pea variety. Exposure of pea leaves to excess light (EL) for 1 h caused a reversible photoinhibition of photosynthesis as showed by changes in Fv / Fm. Although little difference existed between the two pea genotypes with respect to photoinhibition, after 60 min of EL the decline in Fv / Fm was higher in JI281 than in JI399 leaves. As a consequence of EL, H2O2 increased in both pea cultivars, whereas lipid peroxidation and protein oxidation slightly increased, although differences between cultivars were minimal. The redox state of ascorbate shifted towards its oxidized form under EL stress in both cultivars. Transcript levels of genes coding antioxidant enzymes varied with EL in both cultivars, but the response was more pronounced in JI399. The induction observed during EL was maintained or increased after the stress period, as occurred for cytGR and chlMDHAR. GR protein accumulation and activity correlated with the transcript accumulation in JI399, but not in JI288. In this work, a possible role for H2O2 and redox status of ascorbate in the photoxidative stress signalling is discussed.

scholarly journals Local adaptation optimizes photoprotection strategies in a Neotropical legume tree under drought stress

2021 ◽  
Author(s):  
Irene Cordero ◽  
María Dolores Jiménez ◽  
Juan Antonio Delgado ◽  
Luis Balaguer ◽  
José J Pueyo ◽  
...  
Keyword(s):  
Local Adaptation ◽  
Water Availability ◽  
Light Stress ◽  
Photochemical Efficiency ◽  
Carbon Assimilation ◽  
Common Garden ◽  
Thermal Dissipation ◽  
Functional Ecology ◽  
Evaporative Demand ◽  
Legume Tree

Abstract Photoprotection is a plant functional mechanism to prevent photooxidative damage by excess light. This is most important when carbon assimilation is limited by drought, and as such, it entails a trade-off between carbon assimilation vs stress avoidance. The ecological adaptation of plants to local water availability can lead to different photoprotective strategies. To test this, we used different provenances of Caesalpinia spinosa (Mol.) Kuntze (commonly known as ‘tara’) along a precipitation gradient. Tara is a Neotropical legume tree with high ecological and commercial value, found in dry tropical forests, which are increasingly threatened by climate change. Morphological and physiological responses of tara provenances were analysed under three different treatments of drought and leaflet immobilization, i.e., light stress, in a common garden greenhouse experiment. Tara quickly responded to drought by reducing stomatal conductance, evapotranspiration, photochemical efficiency, carbon assimilation and growth, while increasing structural and chemical photoprotection (leaflet angle and pigments for thermal dissipation). Leaflet closure was an efficient photoprotection strategy with overall physiological benefits for seedlings as it diminished the evaporative demand and avoided photodamage, but also entailed costs by reducing net carbon assimilation opportunities. These responses depended on seed origin, with seedlings from the most xeric locations showing the highest dehydration tolerance, suggesting local adaptation and highlighting the value of different strategies under distinct environments. This plasticity in its response to environmental stress allows tara to thrive in locations with contrasting water availability. Our findings increase the understanding of the factors controlling the functional ecology of tara in response to drought, which can be leveraged to improve forecasts of changes in its distribution range, and for planning restoration projects with this keystone tree species.

scholarly journals FMO1 Is Involved in Excess Light Stress-Induced Signal Transduction and Cell Death Signaling

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2163 ◽  
Author(s):  
Weronika Czarnocka ◽  
Yosef Fichman ◽  
Maciej Bernacki ◽  
Elżbieta Różańska ◽  
Izabela Sańko-Sawczenko ◽  
...  
Keyword(s):  
Cell Death ◽  
Signaling Pathways ◽  
Systemic Acquired Resistance ◽  
Light Stress ◽  
Acquired Resistance ◽  
Defense Responses ◽  
Cellular Mechanisms ◽  
Systemic Signal ◽  
Excess Light ◽  
Induced Signal

Because of their sessile nature, plants evolved integrated defense and acclimation mechanisms to simultaneously cope with adverse biotic and abiotic conditions. Among these are systemic acquired resistance (SAR) and systemic acquired acclimation (SAA). Growing evidence suggests that SAR and SAA activate similar cellular mechanisms and employ common signaling pathways for the induction of acclimatory and defense responses. It is therefore possible to consider these processes together, rather than separately, as a common systemic acquired acclimation and resistance (SAAR) mechanism. Arabidopsis thaliana flavin-dependent monooxygenase 1 (FMO1) was previously described as a regulator of plant resistance in response to pathogens as an important component of SAR. In the current study, we investigated its role in SAA, induced by a partial exposure of Arabidopsis rosette to local excess light stress. We demonstrate here that FMO1 expression is induced in leaves directly exposed to excess light stress as well as in systemic leaves remaining in low light. We also show that FMO1 is required for the systemic induction of ASCORBATE PEROXIDASE 2 (APX2) and ZINC-FINGER OF ARABIDOPSIS 10 (ZAT10) expression and spread of the reactive oxygen species (ROS) systemic signal in response to a local application of excess light treatment. Additionally, our results demonstrate that FMO1 is involved in the regulation of excess light-triggered systemic cell death, which is under control of LESION SIMULATING DISEASE 1 (LSD1). Our study indicates therefore that FMO1 plays an important role in triggering SAA response, supporting the hypothesis that SAA and SAR are tightly connected and use the same signaling pathways.

Sun-shade patterns of leaf carotenoid composition in 86 species of neotropical forest plants

2009 ◽  
Vol 36 (1) ◽  
pp. 20 ◽  
Author(s):  
Shizue Matsubara ◽  
G. Heinrich Krause ◽  
Jorge Aranda ◽  
Aurelio Virgo ◽  
Kim G. Beisel ◽  
...  
Keyword(s):  
Woody Species ◽  
Carotenoid Biosynthesis ◽  
Dry Mass ◽  
Daily Basis ◽  
High Irradiance ◽  
Strong Light ◽  
Neotropical Forest ◽  
Forest Plants ◽  
Shade Leaves ◽  
Sun Leaves

A survey of photosynthetic pigments, including 86 species from 64 families, was conducted for leaves of neotropical vascular plants to study sun-shade patterns in carotenoid biosynthesis and occurrence of α-carotene (α-Car) and lutein epoxide (Lx). Under low light, leaves invested less in structural components and more in light harvesting, as manifested by low leaf dry mass per area (LMA) and enhanced mass-based accumulation of chlorophyll (Chl) and carotenoids, especially lutein and neoxanthin. Under high irradiance, LMA was greater and β-carotene (β-Car) and violaxanthin-cycle pool increased on a leaf area or Chl basis. The majority of plants contained α-Car in leaves, but the α- to β-Car ratio was always low in the sun, suggesting preference for β-Car in strong light. Shade and sun leaves had similar β,ε-carotenoid contents per unit Chl, whereas sun leaves had more β,β-carotenoids than shade leaves. Accumulation of Lx in leaves was found to be widely distributed among taxa: >5 mmol mol Chl−1 in 20% of all species examined and >10 mmol mol Chl−1 in 10% of woody species. In Virola elongata (Benth.) Warb, having substantial Lx in both leaf types, the Lx cycle was operating on a daily basis although Lx restoration in the dark was delayed compared with violaxanthin restoration.

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