The dynamics of adaptive evolution in microalgae in a high-CO ocean.

Marine microalgae demonstrate a notable capacity to adapt to high CO and warming in the context of global change. However, the dynamics of their evolutionary processes under simultaneous high CO₂ and warming conditions remain poorly understood. Here, we analyze the dynamics of evolution in experimental populations of a model marine diatom Phaeodactylum tricornutum.

The trade-offs associated with the adaptions of marine microalgae to high CO and warming.

Trade-offs play vital roles in evolutionary theory, linking organism performance to changing environments in the context of global change. Marine microalgae, as one of the most important groups of primary producers in the biosphere, exhibit significant trade-offs across multiple traits in response to environmental changes, such as elevated CO (and consequent ocean acidification) and warming. In this review, we synthesize recent findings on the trade-offs associated with both short-term phenotypic acclimation and long-term genotypic adaptation of marine microalgae.

Cool-edge populations of the kelp under global ocean change scenarios: strong sensitivity to ocean warming but little effect of ocean acidification.

Kelp forests are threatened by ocean warming, yet effects of co-occurring drivers such as CO are rarely considered when predicting their performance in the future. In Australia, the kelp forms extensive forests across seawater temperatures of approximately 7-26°C. Cool-edge populations are typically considered more thermally tolerant than their warm-edge counterparts but this ignores the possibility of local adaptation.

Identity and functional characterisation of the transporter supporting the Na -dependent high-affinity NO uptake in Zostera marina L.

Zostera marina is a seagrass, a group of angiosperms that evolved from land to live submerged in seawater, an environment of high salinity, alkaline pH and usually very low NO . In 2000, we reported the first physiological evidence for the Na -dependent high-affinity NO uptake in this plant. Now, to determine the molecular identity of this process, we searched for NO transporters common to other vascular plants encoded in Z.

DNA methylation and gene transcription act cooperatively in driving the adaptation of a marine diatom to global change.

Genetic changes together with epigenetic modifications such as DNA methylation have been demonstrated to regulate many biological processes and thereby govern the response of organisms to environmental changes. However, how DNA methylation might act cooperatively with gene transcription and thereby mediate the long-term adaptive responses of marine microalgae to global change is virtually unknown. Here we performed a transcriptomic analysis, and a whole-genome bisulfite sequencing, along with phenotypic analysis of a model marine diatom Phaeodactylum tricornutum adapted for 2 years to high CO2 and/or warming conditions.

Avoiding and allowing apatite precipitation in oxygenic photolithotrophs.

The essential elements Ca and P, taken up and used metabolically as Ca and H PO /HPO respectively, could precipitate as one or more of the insoluble forms calcium phosphate (mainly apatite) if the free ion concentrations and pH are high enough. In the cytosol, chloroplast stroma, and mitochondrial matrix, the very low free Ca concentration avoids calcium phosphate precipitation, apart from occasionally in the mitochondrial matrix. The low free Ca concentration in these compartments is commonly thought of in terms of the role of Ca in signalling.

Photon costs of shoot and root NO, and root NH, assimilation in terrestrial vascular plants considering associated pH regulation, osmotic and ontogenetic effects.

The photon costs of photoreduction/assimilation of nitrate (NO) into organic nitrogen in shoots and respiratory driven NO and NH assimilation in roots are compared for terrestrial vascular plants, considering associated pH regulation, osmotic and ontogenetic effects. Different mechanisms of neutralisation of the hydroxyl (OH) ion necessarily generated in shoot NO assimilation are considered. Photoreduction/assimilation of NO in shoots with malic acid synthesis and either accumulation of malate in leaf vacuoles or transport of malate to roots and catabolism there have a similar cost which is around 35% less than that for root NO assimilation and around 20% less than that for photoreduction/assimilation of NO, oxalate production and storage of Ca oxalate in leaf vacuoles.

A mechanistic study of the influence of nitrogen and energy availability on the NH4+ sensitivity of nitrogen assimilation in Synechococcus.

In most algae, NO3- assimilation is tightly controlled and is often inhibited by the presence of NH4+. In the marine, non-colonial, non-diazotrophic cyanobacterium Synechococcus UTEX 2380, NO3- assimilation is sensitive to NH4+ only when N does not limit growth. We sequenced the genome of Synechococcus UTEX 2380, studied the genetic organization of the nitrate assimilation related (NAR) genes, and investigated expression and kinetics of the main NAR enzymes, under N or light limitation.

Potential negative effects of ocean afforestation on offshore ecosystems.

Our scientific understanding of climate change makes clear the necessity for both emission reduction and carbon dioxide removal (CDR). The ocean with its large surface area, great depths and long coastlines is central to developing CDR approaches commensurate with the scale needed to limit warming to below 2 °C. Many proposed marine CDR approaches rely on spatial upscaling along with enhancement and/or acceleration of the rates of naturally occurring processes.

Forensic carbon accounting: Assessing the role of seaweeds for carbon sequestration.

Carbon sequestration is defined as the secure storage of carbon-containing molecules for >100 years, and in the context of carbon dioxide removal for climate mitigation, the origin of this CO is from the atmosphere. On land, trees globally sequester substantial amounts of carbon in woody biomass, and an analogous role for seaweeds in ocean carbon sequestration has been suggested. The purposeful expansion of natural seaweed beds and aquaculture systems, including into the open ocean (ocean afforestation), has been proposed as a method of increasing carbon sequestration and use in carbon trading and offset schemes.

Nucleic acid requirement of plants from low phosphorus habitats. A Commentary on: Foliar nutrient-allocation patterns in Banksia attenuata and Banksia sessilis differing in growth rate and adaptation to low-phosphorus habitats.

This article comments on: Zhongming Han, Jianmin Shi, Jiayin Pang, Li Yan, Patrick M. Finnegan and Hans Lambers. Foliar nutrient allocation patterns in and differing in growth rate and adaptation to low-phosphorus habitats, Annals of Botany, Volume 128, Issue 4, 03 September 2021, Pages 419–430, https://doi.

The maximum growth rate hypothesis is correct for eukaryotic photosynthetic organisms, but not cyanobacteria.

The (maximum) growth rate (µ ) hypothesis predicts that cellular and tissue phosphorus (P) concentrations should increase with increasing growth rate, and RNA should also increase as most of the P is required to make ribosomes. Using published data, we show that though there is a strong positive relationship between the µ of all photosynthetic organisms and their P content (% dry weight), leading to a relatively constant P productivity, the relationship with RNA content is more complex. In eukaryotes there is a strong positive relationship between µ and RNA content expressed as % dry weight, and RNA constitutes a relatively constant 25% of total P.

Determinants, and implications, of the shape and size of thylakoids and cristae.

Thylakoids are flattened sacs isolated from other membranes; cristae are attached to the rest of the inner mitochondrial membrane by the crista junction, but the crista lumen is separated from the intermembrane space. The shape of thylakoids and cristae involves membranes with small (5-30 nm) radii of curvature. While the mechanism of curvature is not entirely clear, it seems to be largely a function of Curt proteins in thylakoids and Mitochondrial Organising Site and Crista Organising Centre proteins and oligomeric FF ATP synthase in cristae.

Protein assemblages and tight curves in the plasma membranes of photosynthetic eukaryotes.

Protein assemblages in the plasma membrane of photosynthetic organisms include the polar occurrence of PIN proteins permitting polar auxin transport in embryophytes and Charales, and the H ATPase in acid zones of Charales cells. Production of small radius of curvature membrane areas in transfer cells and charasomes is incompletely understood.

Inorganic carbon concentrating mechanisms in free-living and symbiotic dinoflagellates and chromerids.

Photosynthetic dinoflagellates are ecologically and biogeochemically important in marine and freshwater environments. However, surprisingly little is known of how this group acquires inorganic carbon or how these diverse processes evolved. Consequently, how CO availability ultimately influences the success of dinoflagellates over space and time remains poorly resolved compared to other microalgal groups.

Will rising atmospheric CO concentration inhibit nitrate assimilation in shoots but enhance it in roots of C plants?

Bloom et al. proposed that rising atmospheric CO concentrations 'inhibit malate production in chloroplasts and thus impede assimilation of nitrate into protein of C plants, a phenomenon that will strongly influence primary productivity and food security under the environmental conditions anticipated during the next few decades'. Previously we argued that the weight of evidence in the literature indicated that elevated atmospheric [CO ] does not inhibit NO assimilation in C plants.

Chloride involvement in the synthesis, functioning and repair of the photosynthetic apparatus in vivo.

Cl has long been known as a micronutrient for oxygenic photosynthetic resulting from its role an essential cofactor for photosystem II (PSII). Evidence on the in vivo Cl distribution in Spinacia oleracea leaves and chloroplasts shows that sufficient Cl is present for the involvement in PSII function, as indicated by in vitro studies on, among other organisms, S. oleracea PsII.