Green algal molecular responses to temperature stress

Barati, Bahram; Gan, Sook Yee; Lim, Phaik Eem; Beardall, John; Phang, Siew Moi

doi:10.1007/s11738-019-2813-1

Cited by 53 publications

(37 citation statements)

References 280 publications

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“…Due the imbalanced absorption and utilization of light induced by cold treatment, over-accumulation of ROS occurs in plants ( O’Kane et al, 1996 ; Ensminger et al, 2006 ; Barati et al, 2019 ). Some cold-exposed green algae significantly increase the content of photoprotective pigments such as antheraxanthin, zeaxanthin, and total carotenes ( Míguez et al, 2020 ).…”

Section: Defense Mechanisms and Protective Proteinsmentioning

confidence: 99%

“…The psychrophiles are characterized by the combination of several traits and the distantly related representatives often employ universal adaptations to permanently low temperatures, such as cold-adapted proteins, increased membrane fluidity, antifreeze proteins, and cryoprotectants (Siddiqui et al, 2013). At present, novel omics approaches allow the acquisition of information on the important features of mesophilic green algae to thrive in cold environment (Barati et al, 2019). The best available model for studying how mesophilic green algae respond to and cope with variations in temperature is Chlamydomonas reinhardtii.…”

Section: Introductionmentioning

confidence: 99%

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Cold Stress Response: An Overview in Chlamydomonas

Ermilova

2020

Front. Plant Sci.

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Low temperature (or cold) is one of the major environmental factors that limit the growth and development of many plants. Various plant species have evolved complex mechanisms to adjust to decreased temperature. Mesophilic chlorophytes are a widely distributed group of eukaryotic photosynthetic organisms, but there is insufficient information about the key molecular processes of their cold acclimation. The best available model for studying how chlorophytes respond to and cope with variations in temperature is the unicellular green alga Chlamydomonas reinhardtii. Chlamydomonas has been widely used for decades as a model system for studying the fundamental mechanisms of the plant heat stress response. At present, unraveling novel coldregulated events in Chlamydomonas has attracted increasing research attention. This mini-review summarizes recent progress on low-temperature-dependent processes in the model alga, while information on other photosynthetic organisms (cyanobacteria and land plants) was used to strengthen generalizations or specializations of cold-induced mechanisms in plant evolution. Here, we describe recent advances in our understanding of cold stress response in Chlamydomonas, discuss areas of controversy, and highlight potential future directions in cold acclimation research.

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Section: Defense Mechanisms and Protective Proteinsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cold Stress Response: An Overview in Chlamydomonas

Ermilova

2020

Front. Plant Sci.

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“…It is also involved in stress alleviation in human diseases, including Parkinson's and Huntington's diseases [52]; however, its exact mechanism of function is not known. It is thought that trehalose can function as a "chemical chaperone" because of its ability to stabilize proteins and other molecular structures under stress conditions [53]. We found that Mut68 contained severely reduced amounts of trehalose because of the insertional disruption of NsTPS3.…”

Section: Discussionmentioning

confidence: 68%

Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production

Ryu

Kang

Jeon

et al. 2020

Biotechnol Biofuels

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Background: The necessity to develop high lipid-producing microalgae is emphasized for the commercialization of microalgal biomass, which is environmentally friendly and sustainable. Nannochloropsis are one of the best industrial microalgae and have been widely studied for their lipids, including high-value polyunsaturated fatty acids (PUFAs). Many reports on the genetic and biological engineering of Nannochloropsis to improve their growth and lipid contents have been published. Results: We performed insertional mutagenesis in Nannochloropsis salina, and screened mutants with high lipid contents using fluorescence-activated cell sorting (FACS). We isolated a mutant, Mut68, which showed improved growth and a concomitant increase in lipid contents. Mut68 exhibited 53% faster growth rate and 34% higher fatty acid methyl ester (FAME) contents after incubation for 8 days, resulting in a 75% increase in FAME productivity compared to that in the wild type (WT). By sequencing the whole genome, we identified the disrupted gene in Mut68 that encoded trehalose-6-phosphate (T6P) synthase (TPS). TPS is composed of two domains: TPS domain and T6P phosphatase (TPP) domain, which catalyze the initial formation of T6P and dephosphorylation to trehalose, respectively. Mut68 was disrupted at the TPP domain in the C-terminal half, which was confirmed by metabolic analyses revealing a great reduction in the trehalose content in Mut68. Consistent with the unaffected N-terminal TPS domain, Mut68 showed moderate increase in T6P that is known for regulation of sugar metabolism, growth, and lipid biosynthesis. Interestingly, the metabolic analyses also revealed a significant increase in stress-related amino acids, including proline and glutamine, which may further contribute to the Mut68 phenotypes. Conclusion: We have successfully isolated an insertional mutant showing improved growth and lipid production. Moreover, we identified the disrupted gene encoding TPS. Consistent with the disrupted TPP domain, metabolic analyses revealed a moderate increase in T6P and greatly reduced trehalose. Herein, we provide an excellent proof of concept that the selection of insertional mutations via FACS can be employed for the isolation of mutants with

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“…Microalgal responses to abiotic stress, such as heat, include reduction in photosynthesis, as a mechanism to balance cellular energy levels necessary for metabolism ( Biswal et al, 2011 ). Other modifications involve alterations of the cellular membrane, changes in protein and carbohydrate production, increase of cellular antioxidant and scavenge mechanisms, increased DNA-repair, as well as the induction of cell death (reviewed by Barati et al, 2019 ). Microalgae exposed to heat stress for a limited time have been shown to be retarded in growth, both in direct connection to the stress and up to 6h afterwards ( Béchet et al, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

Temperature Stress Induces Shift From Co-Existence to Competition for Organic Carbon in Microalgae-Bacterial Photobioreactor Community – Enabling Continuous Production of Microalgal Biomass

et al. 2021

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To better predict the consequences of environmental change on aquatic microbial ecosystems it is important to understand what enables community resilience. The mechanisms by which a microbial community maintain its overall function, for example, the cycling of carbon, when exposed to a stressor, can be explored by considering three concepts: biotic interactions, functional adaptations, and community structure. Interactions between species are traditionally considered as, e.g., mutualistic, parasitic, or neutral but are here broadly defined as either coexistence or competition, while functions relate to their metabolism (e.g., autotrophy or heterotrophy) and roles in ecosystem functioning (e.g., oxygen production, organic matter degradation). The term structure here align with species richness and diversity, where a more diverse community is though to exhibit a broader functional capacity than a less diverse community. These concepts have here been combined with ecological theories commonly used in resilience studies, i.e., adaptive cycles, panarchy, and cross-scale resilience, that describe how the status and behavior at one trophic level impact that of surrounding levels. This allows us to explore the resilience of a marine microbial community, cultivated in an outdoor photobioreactor, when exposed to a naturally occurring seasonal stress. The culture was monitored for 6weeks during which it was exposed to two different temperature regimes (21 ± 2 and 11 ± 1°C). Samples were taken for metatranscriptomic analysis, in order to assess the regulation of carbon uptake and utilization, and for amplicon (18S and 16S rRNA gene) sequencing, to characterize the community structure of both autotrophs (dominated by the green microalgae Mychonastes) and heterotrophs (associated bacterioplankton). Differential gene expression analyses suggested that community function at warm temperatures was based on concomitant utilization of inorganic and organic carbon assigned to autotrophs and heterotrophs, while at colder temperatures, the uptake of organic carbon was performed primarily by autotrophs. Upon the shift from high to low temperature, community interactions shifted from coexistence to competition for organic carbon. Network analysis indicated that the community structure showed opposite trends for autotrophs and heterotrophs in having either high or low diversity. Despite an abrupt change of temperature, the microbial community as a whole responded in a way that maintained the overall level of diversity and function within and across autotrophic and heterotrophic levels. This is in line with cross-scale resilience theory describing how ecosystems may balance functional overlaps within and functional redundancy between levels in order to be resilient to environmental change (such as temperature).

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Green algal molecular responses to temperature stress

Cited by 53 publications

References 280 publications

Cold Stress Response: An Overview in Chlamydomonas

Cold Stress Response: An Overview in Chlamydomonas

Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production

Temperature Stress Induces Shift From Co-Existence to Competition for Organic Carbon in Microalgae-Bacterial Photobioreactor Community – Enabling Continuous Production of Microalgal Biomass

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