Water oxidation is the primary reaction of both natural and artificial photosynthesis. Developing active and robust water oxidation catalysts (WOCs) is the key to constructing efficient artificial ...photosynthesis systems, but it is still facing enormous challenges in both fundamental and applied aspects. Here, the recent developments in molecular catalysts and heterogeneous nanoparticle catalysts are reviewed with special emphasis on biomimetic catalysts and the integration of WOCs into artificial photosystems. The highly efficient artificial photosynthesis depends largely on active WOCs integrated into light harvesting materials via rational interface engineering based on in‐depth understanding of charge dynamics and the reaction mechanism.
As the primary reaction of both natural and artificial photosynthesis, efficient water oxidation by active and robust water oxidation catalysts integrated into light‐harvesting materials with rational interface engineering is the key to realizing efficient artificial photosynthesis. Guidance is provided to give insight into the water oxidation reaction and the status and challenges of this process.
To investigate the effects of elevated atmospheric CO.sub.2 concentrations (CO.sub.2) on autumnal phenology and end of season photosynthesis of different bud-break leaves of trees, we fumigated ...2-year-old red maple seedlings with 800, 600, and 400 muL L.sup.-1 CO.sub.2 in nine continuous stirred tank reactor (CSTR) chambers. Leaves were subdivided into first (B1), second (B2), and third bud-break (B3) leaves. The results indicated that (1) autumnal leaf senescence, including the beginning date, end date, and duration of leaf abscission of all three bud-break leaf groups, was not affected by elevated CO.sub.2; (2) elevated CO.sub.2 increased leaf photosynthesis of B1, B2, and B3 leaves throughout the whole of the growing season; (3) elevated CO.sub.2 significantly increased whole plant photosynthesis only for B2 leaves, accounting for 41.2-54.7% of the whole plant photosynthesis, due to the larger whole leaf area of B2. In conclusion, enhanced seasonal carbon gain in response to atmospheric CO.sub.2 enrichment is the result of strong stimulation of photosynthesis throughout the growing season, especially for B2 leaves but not by extending or shortening the growing season in autumn.
Northern hemisphere evergreen forests assimilate a significant fraction of global atmospheric CO₂ but monitoring large-scale changes in gross primary production (GPP) in these systems is challenging. ...Recent advances in remote sensing allow the detection of solar-induced chlorophyll fluorescence (SIF) emission from vegetation, which has been empirically linked to GPP at large spatial scales. This is particularly important in evergreen forests, where traditional remote-sensing techniques and terrestrial biosphere models fail to reproduce the seasonality of GPP. Here, we examined the mechanistic relationship between SIF retrieved from a canopy spectrometer system and GPP at a winter-dormant conifer forest, which has little seasonal variation in canopy structure, needle chlorophyll content, and absorbed light. Both SIF and GPP track each other in a consistent, dynamic fashion in response to environmental conditions. SIF and GPP are well correlated (R² = 0.62–0.92) with an invariant slope over hourly to weekly timescales. Large seasonal variations in SIF yield capture changes in photoprotective pigments and photosystem II operating efficiency associated with winter acclimation, highlighting its unique ability to precisely track the seasonality of photosynthesis. Our results underscore the potential of new satellite-based SIF products (TROPOMI, OCO-2) as proxies for the timing and magnitude of GPP in evergreen forests at an unprecedented spatiotemporal resolution.
Summary
C4 photosynthetic plants outperform C3 plants in hot and arid climates. By concentrating carbon dioxide around Rubisco C4 plants drastically reduce photorespiration. The frequency with which ...plants evolved C4 photosynthesis independently challenges researchers to unravel the genetic mechanisms underlying this convergent evolutionary switch. The conversion of C3 crops, such as rice, towards C4 photosynthesis is a long‐standing goal. Nevertheless, at the present time, in the age of synthetic biology, this still remains a monumental task, partially because the C4 carbon‐concentrating biochemical cycle spans two cell types and thus requires specialized anatomy. Here we review the advances in understanding the molecular basis and the evolution of the C4 trait, advances in the last decades that were driven by systems biology methods. In this review we emphasise essential genetic engineering tools needed to translate our theoretical knowledge into engineering approaches. With our current molecular understanding of the biochemical C4 pathway, we propose a simplified rational engineering model exclusively built with known C4 metabolic components. Moreover, we discuss an alternative approach to the progressing international engineering attempts that would combine targeted mutagenesis and directed evolution.
Significance Statement
Photosynthesis in C4 plants is more efficient than in C3 plants. Engineering aspects of C4 photosynthesis into C3 crop plants would enable major breakthroughs in increasing crop productivity. Here we review advances in understanding the molecular basis and evolution of the C4 trait, and discuss genetic tools and engineering approaches to achieve this goal.
The initial stimulation of photosynthesis under elevated CO.sub.2 concentrations (eCO.sub.2) is often followed by a decline in photosynthesis, known as CO.sub.2 acclimation. Changes in N levels under ...eCO.sub.2 can have different effects in plants fertilized with nitrate (NO.sub.3.sup.-) or ammonium (NH.sub.4.sup.+) as the N source. NO.sub.3.sup.- assimilation consumes approximately 25% of the energy produced by an expanded leaf, whereas NH.sub.4.sup.+ requires less energy to be incorporated into organic compounds. Although plant-N interactions are important for the productivity and nutritional value of food crops worldwide, most studies have not compared the performance of plants supplied with different forms of N. Therefore, this study aims to go beyond treating N as the total N in the soil or the plant because the specific N compounds formed from the available N forms become highly engaged in all aspects of plant metabolism. To this end, plant N metabolism was analyzed through an experiment with eCO.sub.2 and fertigation with NO.sub.3.sup.- and/or NH.sub.4.sup.+ as N sources for tobacco (Nicotiana tabacum) plants. The results showed that the plants that received only NO.sub.3.sup.- as a source of N grew more slowly when exposed to a CO.sub.2 concentration of 760 mumol mol.sup.-1 than when they were exposed to ambient CO.sub.2 conditions. On the other hand, in plants fertigated with only NH.sub.4.sup.+, eCO.sub.2 enhanced photosynthesis. This was essential for the maintenance of the metabolic pathways responsible for N assimilation and distribution in growing tissues. These data show that the physiological performance of tobacco plants exposed to eCO.sub.2 depends on the form of inorganic N that is absorbed and assimilated.
We investigated post-photosynthetic fractionation and carbon transfer mechanisms of different plant functional types growing under the same climatic conditions in North-eastern China. The variations ...in deltasup.13C of trunk and branches were compared with leaf deltasup.13C at different canopy heights of Pinus koraiensis (evergreen coniferous species), Larix gmelinii (deciduous coniferous species) and Quercus mongolica (deciduous broad-leaved species). Results showed that d C of leaves increased (became more enriched) with increasing canopy height for both coniferous species (P. koraiensis, L. gmelinii) but not for Q. mongolica (a deciduous broad-leaved species). deltasup.13C of both trunk and branches also increased with sampling height for the evergreen conifer P. koraiensis but did not significantly vary for either of the deciduous species (L. gmelinii or Q. mongolica), except a significant increase in branch deltasup.13C for L. gmelinii. Similarly, d C of trunk and branches were strongly correlated with leaf deltasup.13C only in the evergreen conifer, P. koraiensis. sup.13C was consistently more enriched in trunk, branches, and roots compared to leaves in all three species. Our findings suggest that, even under the same climatic conditions, different plant functional types may exhibit different carbon transfer mechanisms. This is contrary to the previous hypothesis that different carbon transfer mechanisms operate in forests of different climatic zones, especially in tropical and temperate forests. Particularly, the differences occur predominantly between evergreen and deciduous trees rather than between coniferous and broad-leaved trees. The significant difference in deltasup.13C between leaves and wood tissues confirms a previous post-photosynthetic isotope fractionation in temperate forests. Keywords deltasup.13C * Functional type * Canopy height * Carbon transfer * Temperate forest
Cyanobacteria are the only prokaryotes to have evolved oxygenic photosynthesis, transforming the biology and chemistry of our planet. Genomic and evolutionary studies have revolutionized our ...understanding of early oxygenic phototrophs, complementing and dramatically extending inferences from the geologic record. Molecular clock estimates point to a Paleoarchean origin (3.6–3.2 billion years ago, bya) of the core proteins of Photosystem II (PSII) involved in oxygenic photosynthesis and a Mesoarchean origin (3.2–2.8 bya) for the last common ancestor of modern cyanobacteria. Nonetheless, most extant cyanobacteria diversified after the Great Oxidation Event (GOE), an environmental watershed ca. 2.45 bya made possible by oxygenic photosynthesis. Throughout their evolutionary history, cyanobacteria have played a key role in the global carbon cycle.
The core proteins of PSII involved in oxygenic photosynthesis originated during the early Archean, well before the GOE occurring around 2.3 billion years ago.Most extant cyanobacterial taxa, including the lineage leading to chloroplasts, diversified after the GOE.The evolution of modern planktonic cyanobacteria and phytoplanktonic algae reached global prominence at the end of the Precambrian, and they continue to significantly contribute to the carbon cycle.Prior to the origin of complex life, cyanobacteria were the main primary producers during most of the Proterozoic Eon.
C3‐C4 intermediate photosynthesis has evolved at least five times convergently in the Brassicaceae, despite this family lacking bona fide C4 species. The establishment of this carbon concentrating ...mechanism is known to require a complex suite of ultrastructural modifications, as well as changes in spatial expression patterns, which are both thought to be underpinned by a reconfiguration of existing gene‐regulatory networks. However, to date, the mechanisms which underpin the reconfiguration of these gene networks are largely unknown.
In this study, we used a pan‐genomic association approach to identify genomic features that could confer differential gene expression towards the C3‐C4 intermediate state by analysing eight C3 species and seven C3‐C4 species from five independent origins in the Brassicaceae.
We found a strong correlation between transposable element (TE) insertions in cis‐regulatory regions and C3‐C4 intermediacy. Specifically, our study revealed 113 gene models in which the presence of a TE within a gene correlates with C3‐C4 intermediate photosynthesis. In this set, genes involved in the photorespiratory glycine shuttle are enriched, including the glycine decarboxylase P‐protein whose expression domain undergoes a spatial shift during the transition to C3‐C4 photosynthesis. When further interrogating this gene, we discovered independent TE insertions in its upstream region which we conclude to be responsible for causing the spatial shift in GLDP1 gene expression.
Our findings hint at a pivotal role of TEs in the evolution of C3‐C4 intermediacy, especially in mediating differential spatial gene expression.
Brassicaceae species with C3‐C4 intermediate photosynthesis show an enrichment of transposons upstream of photorespiratory genes, such as those encoding glycine decarboxylase proteins.
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![Variation of [delta][sup.13...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1385-0237/small "Variation of [delta][sup.13]C of wood and foliage with canopy height differs between evergreen and deciduous species in a temperate forest")
