Photosynthesis: From Natural Towards Artificial

Photosynthesis, the natural process that yields food, fuel and fibre, spans physical and biological sciences, spatially from atomic scales to the global and temporally from electronic transitions to the evolutionary time frame. Photosynthesis is highly efficient in its primary energy capture, but much less so in terms of conversion to crop yield. The natural photosynthetic system provides fertile ground for exploring and dissecting partial processes that may be mimicked inartificial systems for human needs, perhaps with improved efficiency. Future developments are limited only by the imagination. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preface: photosynthesis and hydrogen energy research for sustainability

Energy supply, climate change, and global food security are among the main chalenges facing humanity in the twenty-first century. Despite global energy demand is continuing to increase, the availability of low cost energy is decreasing. Together with the urgent problem of climate change due to CO₂ release from the combustion of fossil fuels, there is a strong requirement of developing the clean and renewable energy system for the hydrogen production. Solar fuel, biofuel, and hydrogen energy production gained unlimited possibility and feasibility due to understanding of the detailed photosynthetic system structures. This special issue contains selected papers on photosynthetic and biomimetic hydrogen production presented at the International Conference “Photosynthesis Research for Sustainability–2016”, that was held in Pushchino (Russia), during June 19–25, 2016, with the sponsorship of the International Society of Photosynthesis Research (ISPR) and of the International Association for Hydrogen Energy (IAHE). This issue is intended to provide recent information on the photosynthetic and biohydrogen production to our readers.     

Environment-dependent metabolic investments in the mixotrophic chrysophyte Ochromonas

Mixotrophic protists combine photosynthesis and phagotrophy to obtain energy and nutrients. Because mixotrophs can act as either primary producers or consumers, they have a complex role in marine food webs and biogeochemical cycles. Many mixotrophs are also phenotypically plastic and can adjust their metabolic investments in response to resource availability. Thus, a single species's ecological role may vary with environmental conditions. Here, we quantified how light and food availability impacted the growth rates, energy acquisition rates, and metabolic investment strategies of eight strains of the mixotrophic chrysophyte, Ochromonas. All eight Ochromonas strains photoacclimated by decreasing chlorophyll content as light intensity increased. Some strains were obligate phototrophs that required light for growth, while other strains showed stronger metabolic responses to prey availability. When prey availability was high, all eight strains exhibited accelerated growth rates and decreased their investments in both photosynthesis and phagotrophy. Photosynthesis and phagotrophy generally produced additive benefits: In low-prey environments, Ochromonas growth rates increased to maximum, light-saturated rates with increasing light but increased further with the addition of abundant bacterial prey. The additive benefits observed between photosynthesis and phagotrophy in Ochromonas suggest that the two metabolic modes provide nonsubstitutable resources, which may explain why a tradeoff between phagotrophic and phototrophic investments emerged in some but not all strains.     

Here comes the sun: How optimization of photosynthetic light reactions can boost crop yields

Photosynthesis started to evolve some 3.5 billion years ago CO₂ is the substrate for photosynthesis and in the past 200–250 years, atmospheric levels have approximately doubled due to human industrial activities. However, this time span is not sufficient for adaptation mechanisms of photosynthesis to be evolutionarily manifested. Steep increases in human population, shortage of arable land and food, and climate change call for actions, now. Thanks to substantial research efforts and advances in the last century, basic knowledge of photosynthetic and primary metabolic processes can now be translated into strategies to optimize photosynthesis to its full potential in order to improve crop yields and food supply for the future. Many different approaches have been proposed in recent years, some of which have already proven successful in different crop species. Here, we summarize recent advances on modifications of the complex network of photosynthetic light reactions. These are the starting point of all biomass production and supply the energy equivalents necessary for downstream processes as well as the oxygen we breathe.     

Effects of excess light energy on excitation-energy dynamics in a pennate diatom Phaeodactylum tricornutum

Photosynthesis Research - Photosynthesis starts when a pigment in the photosynthetic antennae absorbs a photon. The electronic excitation energy is then transferred through the network of...     

Improving carbon fixation pathways

A recent resurgence in basic and applied research on photosynthesis has been driven in part by recognition that fulfilling future food and energy requirements will necessitate improvements in crop carbon-fixation efficiencies. Photosynthesis in traditional terrestrial crops is being reexamined in light of molecular strategies employed by photosynthetic microbes to enhance the activity of the Calvin cycle. Synthetic biology is well-situated to provide original approaches for compartmentalizing and enhancing photosynthetic reactions in a species independent manner. Furthermore, the elucidation of alternative carbon-fixation routes distinct from the Calvin cycle raises possibilities that novel pathways and organisms can be utilized to fix atmospheric carbon dioxide into useful materials.     

Tuning the redox potential of tyrosine-histidine bioinspired assemblies

Photosynthesis Research - Photosynthesis powers our planet and is a source of inspiration for developing artificial constructs mimicking many aspects of the natural energy transducing process. In...     

光合作用与农业生产

光合作用被誉为是地球上最重要的化学反应,没有光合作用就不可能有人类社会的产生和发展。光合作用是作物产量形成的物质基础,如何充分利用太阳能进行光合作用是农业生产中的一个根本性问题。文章从作物光能利用率与光合作用效率、光合作用过程及其运转的调控、农业发展动向与高光效三个方面简要分析了光合作用与农业生产的关系,以期为今后的相关研究提供一些思考。     

A generalised dynamic model of leaf-level C3 photosynthesis combining light and dark reactions with stomatal behaviour

Photosynthesis Research - Global food demand is rising, impelling us to develop strategies for improving the efficiency of photosynthesis. Classical photosynthesis models based on steady-state...     

What is the maximum efficiency with which photosynthesis can convert solar energy into biomass?

Photosynthesis is the source of our food and fiber. Increasing world population, economic development, and diminishing land resources forecast that a doubling of productivity is critical in meeting agricultural demand before the end of this century. A starting point for evaluating the global potential to meet this goal is establishing the maximum efficiency of photosynthetic solar energy conversion. The potential efficiency of each step of the photosynthetic process from light capture to carbohydrate synthesis is examined. This reveals the maximum conversion efficiency of solar energy to biomass is 4.6% for C3 photosynthesis at 30 degrees C and today's 380 ppm atmospheric [CO2], but 6% for C4 photosynthesis. This advantage over C3 will disappear as atmospheric [CO2] nears 700 ppm.     

光合作用各部分反应间的动态衔接与协调

光合作用是地球上最重要的化学反应,由种类繁多、性质各异的反应步骤联系起来。要使光合机构在不断变化的环境中仍能适应运转,它需要随时协调各个部分反应间的关系。本文主要综述了光合能量转换过程中类囊体膜的动态结构变化、同化力组分调节、光合作用原初反应对光照变化的响应及能量转换反应与二氧化碳同化过程的配合等。     

How do rice seedlings of landrace Pokkali survive in saline fields after transplantation? Physiology,biochemistry, and photosynthesis

Photosynthesis Research - Rice, one of the most important staple food crops in the world, is highly sensitive to soil salinity at the seedling stage. The ultimate yield of this crop is a function...     

Reconstruction of the absorption spectrum of Synechocystis sp. PCC 6803 optical mutants from the in vivo signature of individual pigments

Photosynthesis Research - In this work, we reconstructed the absorption spectrum of different Synechocystis sp. PCC 6803 optical strains by summing the computed signature of all pigments present in...     

Mitigation of drought-induced oxidative damage by enhanced carbon assimilation and an efficient antioxidative metabolism under high CO2 environment in pigeonpea (Cajanus cajan L.)

Photosynthesis Research - In the current study, pigeonpea (Cajanus cajan L.), a promising legume food crop was assessed for its photosynthetic physiology, antioxidative system as well as C and N...     

Photostasis and cold acclimation: sensing low temperature through photosynthesis

Photosynthesis is a highly integrated and regulated process which is highly sensitive to any change in environmental conditions, because it needs to balance the light energy absorbed by the photosystems with the energy consumed by metabolic sinks of the plant. Low temperatures exacerbate an imbalance between the source of energy and the metabolic sink, thus requiring adjustments of photosynthesis to maintain the balance of energy flow. Photosynthesis itself functions as a sensor of this imbalance through the redox state of photosynthetic electron-transport components and regulates photophysical, photochemical and metabolic processes in the chloroplast. Recent progress has been made in understanding how plants sense the low temperature signal. It is clear that photosynthesis interacts with other processes during cold acclimation involving crosstalk between photosynthetic redox, cold acclimation and sugar-signalling pathways to regulate plant acclimation to low temperatures.     

Cationic penetrating antioxidants switch off Mn cluster of photosystem II in situ

Photosynthesis Research - Photosystem I (PSI) generates the most negative redox potential found in nature, and the performance of solar energy conversion into alternative energy sources in...     

Dynamics of regulated YNPQ and non-regulated YNO energy dissipation in sunflower leaves exposed to sinusoidal lights

Photosynthesis Research - Better understanding of photosynthetic efficiency under fluctuating light requires a specific approach to characterize the dynamics of energy dissipation in photosystem...     

The International Society of Photosynthesis Research (ISPR) and its associated International Congress on Photosynthesis (ICP): a pictorial report

We present here some thoughts on the origin of the International Society of Photosynthesis Research (ISPR). We provide two tables, one of the Officers of the ISPR and the International Photosynthesis Committee, and the other of the Organizers of the International Congress of Photosynthesis (ICP) from the 14th ICP (PS07 in Glasgow) to the 9th ICP (in Nagoya). In celebration of the 14th ICP, we provide here a collection of photographs of the many involved in the ISPR and the ICP as well as some of the others. We end this presentation with the list of members of the committees of the ISPR. If there are any errors in this report, we request the readers to send them to one of us (G; gov@uiuc.edu). Further, we are seeking recollections on ISPR and the Congresses from all the readers of the events during the 1992–1998 period. Hopefully, these will shed further light on the origin and the evolution of the ISPR. These will aid in the preparation of a more complete history of the origin and the evolution of ISPR for publication in 2008.     

Quenching of chlorophyll triplet states by carotenoids in algal light-harvesting complexes related to fucoxanthin-chlorophyll protein

Photosynthesis Research - We have used time-resolved absorption and fluorescence spectroscopy with nanosecond resolution to study triplet energy transfer from chlorophylls to carotenoids in a...     

Effect of disorder and polarization sequences on two-dimensional spectra of light-harvesting complexes

Photosynthesis Research - Two-dimensional electronic spectra (2DES) provide unique ways to track the energy transfer dynamics in light-harvesting complexes. The interpretation of the peaks and...