Extremophyte adaptations to salt and water deficit stress

Barak, Simon; Farrant, Jill M.

doi:10.1071/fpv43n7_fo

Cited by 15 publications

(9 citation statements)

References 48 publications

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“…These include shifts in metabolic profiles and the accumulation of compatible solutes. A key issue is the adaptation of the photosynthetic apparatus because continued photosynthetic activity under high light, and especially in combination with desiccation, may lead to the production of reactive oxygen species that will cause damage to the entire cell (10)(11)(12). The cyanobacteria that colonize sand crusts evolved strategies for coping with these daily cycles of hydration using mechanisms that enable extensive quenching of absorbed light energy.…”

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confidence: 99%

Changes in aggregation states of light-harvesting complexes as a mechanism for modulating energy transfer in desert crust cyanobacteria

Eyal

Choubeh

Cohen

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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In this paper we propose an energy dissipation mechanism that is completely reliant on changes in the aggregation state of the phycobilisome light-harvesting antenna components. All photosynthetic organisms regulate the efficiency of excitation energy transfer (EET) to fit light energy supply to biochemical demands. Not many do this to the extent required of desert crust cyanobacteria. Following predawn dew deposition, they harvest light energy with maximum efficiency until desiccating in the early morning hours. In the desiccated state, absorbed energy is completely quenched. Time and spectrally resolved fluorescence emission measurements of the desiccated desert crust Leptolyngbya ohadii strain identified (i) reduced EET between phycobilisome components, (ii) shorter fluorescence lifetimes, and (iii) red shift in the emission spectra, compared with the hydrated state. These changes coincide with a loss of the ordered phycobilisome structure, evident from small-angle neutron and X-ray scattering and cryo-transmission electron microscopy data. Based on these observations we propose a model where in the hydrated state the organized rod structure of the phycobilisome supports directional EET to reaction centers with minimal losses due to thermal dissipation. In the desiccated state this structure is lost, giving way to more random aggregates. The resulting EET path will exhibit increased coupling to the environment and enhanced quenching.eserts cover almost half of the Earth's terrestrial surface, and although desert conditions may seem unfavorable, they are home for diverse ecosystems. Many of these ecosystems are founded on biological desert crusts, which play an essential role in stabilizing shifting sands and enriching them with nutrients (1, 2). Cyanobacteria are among the first microorganisms to inhabit these crusts where one of the major sources of water is often dew deposited before dawn (3, 4). However, as temperatures elevate, water quickly evaporates. Such conditions can be extremely harmful for photosynthetic organisms and require adaptations on all cellular levels (3-9). These include shifts in metabolic profiles and the accumulation of compatible solutes. A key issue is the adaptation of the photosynthetic apparatus because continued photosynthetic activity under high light, and especially in combination with desiccation, may lead to the production of reactive oxygen species that will cause damage to the entire cell (10-12). The cyanobacteria that colonize sand crusts evolved strategies for coping with these daily cycles of hydration using mechanisms that enable extensive quenching of absorbed light energy. The extent of quenching in these organisms far exceeds that of common laboratory model organisms (13, 14).Our studies focused on Leptolyngbya ohadii, a crust cyanobacterium isolated from the Nizzana region of the NW Negev desert in Israel (3,6). This is a keystone organism in this environment (4). To maintain L. ohadii cells in a viable state the desiccation process must be gradual (3). Recovery o...

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confidence: 99%

Changes in aggregation states of light-harvesting complexes as a mechanism for modulating energy transfer in desert crust cyanobacteria

Eyal

Choubeh

Cohen

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Salinity, along with drought, cause changes in osmotic pressure and oxidative stress that trigger cellular damage and dehydration [78]. To deal with this, several strategies can be used by plants, including accumulation of osmolytes to lower cellular osmotic potential, activation of antioxidant systems for ROS removal and increase in chaperone activities for protein protection [79]. For example, synthesis of proline, an amino acid that can function as an osmolyte and osmoprotectant, is usually promoted under the stress condition by enhancement activities of P5CS, the rate-limiting enzyme in the proline biosynthetic pathway [75,80].…”

Section: Expression Levels Of Other Stress-related Genes Are Also Enhanced In Transgenic Plants Under Salinity Conditionsmentioning

confidence: 99%

The Drought-Mediated Soybean GmNAC085 Functions as a Positive Regulator of Plant Response to Salinity

Hoang

Chuong

Hoa

et al. 2021

IJMS

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Abiotic stress factors, such as drought and salinity, are known to negatively affect plant growth and development. To cope with these adverse conditions, plants have utilized certain defense mechanisms involved in various aspects, including morphological, biochemical and molecular alterations. Particularly, a great deal of evidence for the biological importance of the plant-specific NAM, ATAF1/2, CUC2 (NAC) transcription factors (TFs) in plant adaptation to abiotic stress conditions has been reported. A previous in planta study conducted by our research group demonstrated that soybean (Glycine max) GmNAC085 mediated drought resistance in transgenic Arabidopsis plants. In this study, further characterization of GmNAC085 function in association with salt stress was performed. The findings revealed that under this condition, transgenic soybean plants overexpressing GmNAC085 displayed better germination rates than wild-type plants. In addition, biochemical and transcriptional analyses showed that the transgenic plants acquired a better defense system against salinity-induced oxidative stress, with higher activities of antioxidant enzymes responsible for scavenging hydrogen peroxide or superoxide radicals. Higher transcript levels of several key stress-responsive genes involved in the proline biosynthetic pathway, sodium ion transporter and accumulation of dehydrins were also observed, indicating better osmoprotection and more efficient ion regulation capacity in the transgenic lines. Taken together, these findings and our previous report indicate that GmNAC085 may play a role as a positive regulator in plant adaptation to drought and salinity conditions.

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“…Less than five percent of land plants are capable of resilient growth under high salinities represented by extremophytes (Santos et al ., 2016). Extremophytes are broadly categorized as plants highly tolerant of multiple environmental stresses (Barak and Farrant, 2016). Increasing soil salinities are always growth inhibitory to plants at some intensity but extremophytes show a higher tolerance capacity (Santiago-Rosario et al ., 2021; Zhang et al ., 2018).…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal gene expression atlas of the extremophyteSchrenkiella parvula

Wijesinghege

Wang

Pantha

et al. 2022

Preprint

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Extremophytes are naturally selected to survive environmental stresses, but scarcity of genetic resources for them developed with spatiotemporal resolution limit their use in stress biology. Schrenkiella parvula is one of the leading extremophyte models with initial molecular genomic resources developed to study its tolerance mechanisms to high salinity. Here we present a transcriptome atlas for S. parvula with subsequent analyses to highlight its diverse gene expression networks associated with salt responses. We included spatiotemporal expression profiles, expression specificity of each gene, and co-expression and functional gene networks representing 115 transcriptomes sequenced from 35 tissue and developmental stages examining their responses before and after 27 salt treatments in our current study. The highest number of tissue-preferentially expressed genes were found in seeds and siliques while genes in seedlings showed the broadest expression profiles among developmental stages. Seedlings had the highest magnitude of overall transcriptomic responses to salinity compared to mature tissues and developmental stages. Differentially expressed genes in response to salt were largely mutually exclusive but shared common stress response pathways spanning across tissues and developmental stages. Our foundational dataset created for S. parvula representing a stress-adapted wild plant lays the groundwork for future functional, comparative, and evolutionary studies using extremophytes aiming to uncover novel stress tolerant mechanisms.

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Extremophyte adaptations to salt and water deficit stress

Cited by 15 publications

References 48 publications

Changes in aggregation states of light-harvesting complexes as a mechanism for modulating energy transfer in desert crust cyanobacteria

Changes in aggregation states of light-harvesting complexes as a mechanism for modulating energy transfer in desert crust cyanobacteria

The Drought-Mediated Soybean GmNAC085 Functions as a Positive Regulator of Plant Response to Salinity

Spatiotemporal gene expression atlas of the extremophyteSchrenkiella parvula

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