At the dawn of the 21^st century, the rapid expansion of manufacturing plants and the widespread destruction of natural habitats significantly contributed to accelerating global warming. This phenomenon has led to severe droughts, irreversible agricultural damage, and substantial challenges in securing food supplies for the burgeoning global population. The alarming surge in atmospheric carbon dioxide concentrations underscores the urgent need to embrace clean energy technologies. To date, the primary goal of mankind is to develop innovative approaches to return Earth's ecology to its pre-industrial condition, as a century ago. The special issue (SI) in the International Journal of Hydrogen Energy presents a collection of papers on photosynthetic and biomimetic hydrogen (H₂) production, presented at the 'Photosynthesis and Hydrogen Energy Research for Sustainability - 2023' conference, held in Istanbul, Turkey, from 3-9 July 2023 (https://phrs-conference.com). The event was supported by the International Society of Photosynthesis Research (ISPR) and the International Association for Hydrogen Energy (IAHE). SI aims to deliver the latest insights into sustainable energy, with a particular emphasis on Biohydrogen and Artificial Photosynthesis. At the conference, nine promising young investigators were honoured with awards. Included herein are photographs capturing the conference's congenial atmosphere. We cordially invite you to the 12^th International Meeting of 'Photosynthesis and Hydrogen Energy Research for Sustainability - 2024', honouring esteemed researchers John Allen (UK), Eva-Mari Aro (Finland), Ibrahim Dincer (Canada), Kazunari Domen (Japan), Elizabeth Gantt (USA), Andrey Rubin (Russia), and scheduled to take place in Turkey (13-19 October 2024).

I present here a personal perspective of the evolution of the two-light reaction two-pigment scheme for the electron transport in oxygenic photosynthesis - as I have lived through it - first as a graduate student of Robert Emerson, from September 1956-January 1959, and then of Eugene Rabinowitch from February 1959-September 1960. I have provided here some of the key published work in my way and have also provided a few photographs. It is essential to remind ourselves upfront that different individuals may have different recollections of the same event (see e.g., the Japanese movie 'Rashomon' https://en.wikipedia.org/wiki/Rashomon). Thus, I encourage others to write about their perspective. Further, I recognize, upfront, the support and encouragement I have received from Robert Blankenship for writing this perspective, and from Győző Garab for submission of this story to Photosynthetica. I begin my perspective with a dedication to Robert Emerson, whose pioneering work led to the concept of the two-light reaction two-pigment system in oxygenic photosynthesis.

This Special Issue of Photosynthetica is dedicated to celebrating the distinguished scientific life and 75^th birthday of Professor Suleyman I. Allakhverdiev (born 1 August 1950), whose contributions have left an enduring mark on modern photosynthesis research, photobiology, and bioenergetics. His pioneering studies of Photosystem II advanced the field in fundamental ways, including establishing pheophytin as the primary electron acceptor, defining the functional Mn₄ water-oxidizing cluster and its reconstitution, and clarifying the redox properties of key cofactors such as Q_A, Q_B, and P₆₈₀. He also significantly deepened understanding of photoinhibition by distinguishing donor- and acceptor-side processes and illuminating broader roles for bicarbonate in proton management and repair. Building on these mechanistic insights, his work helped inspire artificial photosynthesis, catalytic systems for water oxidation and hydrogen evolution, and biohybrid energy platforms. As a scholar, editor, organizer, mentor, and scientific diplomat, Professor Allakhverdiev has built a truly global legacy that this Special Issue is proud to honor.

Afromontane forests are an important part of the KwaZulu Natal region of southern Africa, having a distinctive flora with a high proportion of endemic species, and lichens are keystone members. Unlike other continental areas, KwaZulu Natal climate change is predicted to increase rainfall and cloudiness. In the present study, hydrated Afromontane lichens from both exposed and shaded microhabitats were given either constant [100 µmol(photon) m^-2 s^-1] or fluctuating [0, 200, 0 µmol(photon) m^-2 s^-1] light for 8 h a day for 3 d and changes monitored in nonphotochemical quenching (NPQ) and rates of photosynthetic electron transport. In sun but not shade collections, NPQ strongly increased following treatment with constant and fluctuating light. It seems likely that CO₂ fixation may be reduced in moist thalli, and the increase in NPQ may reduce ROS formation during exposure to light while hydrated. Sun lichens can readily modify their NPQ in response to increased cloudiness and rainfall expected in KwaZulu Natal.

We honor Professor Hartmut Karl Lichtenthaler, a versatile pioneer of photosynthesis research, plant physiology, isoprenoid biochemistry, and stress physiology of plants, for his groundbreaking and creative contributions to plant science. His innovative research on the chemical composition, ultrastructure, and function of chloroplasts and his detection of the major methylerythritol 4-phosphate (MEP) isoprenoid biosynthetic pathway in plants is key to our current understanding of the physiology and biochemistry of photosynthesis systems. His ingenious use of the powerful laser-induced chlorophyll a fluorescence imaging has helped us better understand the stress response processes in plant leaves. In this tribute, we present a summary of Lichtenthalerꞌs career, significant scientific contributions, editorial engagement, promotion of international cooperation, many honors, and awards, as well as his devotion to hiking and mountaineering.

The International Conference on "Photosynthesis and Hydrogen Energy Research" was inaugurated in 2004 in Trois Rivières, Canada, as "Photosynthesis and Post-Genomics Era". It was conceived by its founders, Suleyman I. Allakhverdiev (Russia), Vyacheslav (Slava) Klimov (Russia), Robert Carpentier (Canada), and Prasanna Mohanty (India) to be an alternating conference to the bigger International Congress on Photosynthesis, which was then held every three years. The name was changed to the International Conference on Photosynthesis (ICP) in 2011. In 2013, "Hydrogen Production" was added, and then finally the current name, "International Conference on Photosynthesis and Hydrogen Energy Research for Sustainability", was used in 2015. The conferences over the last twenty years have been held in three continents - North America, Europe, and Asia - and have been very successful in attracting participants with the latest ideas in photosynthesis, hydrogen production, and energy sustainability. Here we describe all 12 conferences, with details of the major events of each conference. Major points of the conference were: (1) Recent advances in the understanding of the basic mechanisms of water splitting (photosystem II) and the reactions around photosystem I in photosynthetic organisms. (2) The role of hydrogen production in photosynthesis. (3) The role of innovations in photosynthesis and hydrogen production in the development of global sustainability.

This study aimed to evaluate the effectiveness of silicon (0.5 and 1.0 mM), applied through seed priming, foliar spray, and their combined application, in enhancing drought tolerance in buckwheat under 30% field water capacity by modulating key physiological mechanisms. Drought markedly reduced growth attributes and impaired PSII efficiency and gas exchange. Under drought conditions, the combined 1.0 mM Si treatment increased fresh and dry biomass by 54 and 96%, respectively, and enhanced leaf thickness by 39% compared with untreated plants. The photosynthetic rate increased from -0.22 to 1.87 µmol(CO₂) m^-2 s^-1, stomatal conductance and transpiration rose nearly 13-fold, intercellular CO₂ concentration decreased by 32%, and key PSII parameters improved markedly, with the effective quantum yield of PSII increasing by 112% and the performance index by 2.65-fold. Overall, the results demonstrate that combining Si-seed priming with foliar application effectively enhanced plant drought resilience.

I present here the story of my personal and scientific life. I provide information on my parents, my childhood, schooling, education at the Wageningen Agricultural University, and the work for my PhD degree on the action of some herbicides on photosynthesis under the guidance of Professor Evert Christiaan Wassink. After graduation, I obtained a position as a professor. In 1977, I spent a one-year sabbatical with Professor Govindjee at the University of Illinois at Urbana-Champaign, USA. This was the start of a long-time and successful cooperation on the effects of bicarbonate on Photosystem II. The research on the impact of herbicides on photosynthesis was extended in cooperation with Professor Ko Wakabayashi and his co-workers at the Tamagawa University at Machida-shi, Tokyo, Japan. Another topic of my research was the photoinhibition of PSII by too much light; for this, I worked with Professor Christa Critchley at the University of Queensland in Brisbane, Australia. At the end, I list my service in several professional committees.

Tetraploidization was induced in the drought-tolerant tomato landrace 'de Ramellet' to evaluate its physiological and anatomical response under well-watered (WW) and water-deficient (WD) conditions. Under WW, tetraploid plants exhibited approximately 40% lower stomatal density and approximately 80% larger stomata than diploids. Net photosynthetic rate (P_N), intrinsic water-use efficiency, and intercellular CO₂ concentration remained unchanged between diploids and tetraploids. Under WD, both genotypes reduced P_N and stomatal conductance by similar proportions; however, only diploids decreased leaf area and adjusted stomatal density and size, whereas the tetraploid maintained stomatal traits similarly to those in WW conditions. However, both genotypes maintained similar photosynthetic capacity under WD despite different stomatal display and total pore area, which suggests the involvement of morphophysiological mechanisms beyond stomatal traits, such as root traits and hydraulic regulation.

Chlorophyll (Chl) a fluorescence measurements are widely used in the study of photosynthesis, and Reto Strasser is a well-known pioneer in this domain. In 2019, the current authors, together with Vineet Soni, and Neera Bhalla Sarin, celebrated his 75^th birthday. Here, we pay tribute to him on his 82^nd birthday through a brief description of the key results we had obtained with him, over the years, on the understanding and exploitation of the OJIP Chl a fluorescence transient. The topics of these studies have been quite diverse, from the oxygen clock, the bicarbonate effect in Photosystem II, the adaptability of plants to various stress factors, to mathematical modeling of the OJIP phase, but all based on the application of Chl a fluorescence for the understanding of oxygenic photosynthesis. Additionally, we have included here a list of the authors who have honored Reto Strasser in Photosynthetica in 2020, along with references of their papers.

The effects of the light-emitting diode (LED) spectra on plant growth, flowering, and phytochemical accumulation of African marigold were assessed under controlled conditions. The combination of white, blue, and red LEDs prolonged the time to flower by up to 20 d compared to full white LEDs and other light treatments. The white LEDs are an insufficient lighting condition for marigold growth, indicated by the lower plant and flower biomass. The dichromatic blue-red light and the white-blue-red (WBR) light were most suitable for marigold growth, biomass production, as well as flower quantity and quality. In addition, the highest contents of flavonoids and phenolics were observed in leaves and petals of marigold plants under the WBR treatment. Importantly, the extended spectrum of LEDs, achieved by supplementing white LEDs with the blue-red LEDs, could provide a friendly visual environment for researchers and workers under closed environments and plant factories.

The upland cotton strain YA-1 can be used for hybrid seed production and recurrent selection. However, the effect of YA-1 virescent phenotype on photosynthetic traits remains unclear. This study demonstrated that the chlorophyll and carotenoid contents, light-saturation point, light-compensation point, and PSⅡ reaction center activities are lower than those of green leaves of wide type. In contrast, light-energy utilization efficiencies, net photosynthetic rate, transpiration rate, stomatal conductance, concentrations of Rubisco and phosphoenolpyruvate carboxylase, photosynthetic performance indices, and energy distribution parameters of the yellowish leaves of YA-1 are higher than those of wild type green leaves. The lower expression of GhHemL, GhSGRL, and GhCAO genes impairs chlorophyll biosynthesis, while the downregulation of GhZEP and GhNCED disrupts carotenoid biosynthesis, altering the pigment composition in yellowish leaves. The yellowish phenotype of YA-1 had significant positive effects on photosynthetic efficiency. This finding provides a valuable basis for optimizing the use of YA-1 in cotton breeding programs.

It is both a privilege and a pleasure to celebrate the upcoming 95^th birthday of Pierre Joliot, one of the most influential figures in modern photosynthesis research. Across more than seven decades of scientific activity, Pierre has transformed our understanding of oxygenic photosynthesis through pioneering studies of oxygen evolution, excitation-energy transfer, photosynthetic electron transport, and membrane bioenergetics. His discoveries helped establish fundamental concepts that continue to guide contemporary research, including the now-classic period-four oscillation of oxygen evolution and the mechanistic framework underlying the Kok-Joliot model of water oxidation. Pierre Joliot is also part of one of the most remarkable scientific families in history. The Curie-Joliot family has been associated with three Nobel Prizes and generations of groundbreaking discoveries that have shaped both physics and chemistry. Yet Pierre's own scientific accomplishments stand firmly on their own merit and have earned him an enduring place among the pioneers of photosynthesis research. In this tribute, we briefly discuss the origins of the Joliot and Joliot-Curie names, summarize Pierre's education, scientific career, leadership roles, and honors, and highlight selected contributions that have profoundly influenced our understanding of photosynthesis. Above all, we celebrate a scientist whose curiosity, creativity, rigor, and humanity have inspired colleagues, students, and friends around the world.

The aim was to investigate the morphological, photosynthetic, and hydraulic physiological characteristics of different genotypes of Coffea canephora under controlled cultivation conditions. Growth, conductance, and hydraulic conductivity of the root system of 16 C. canephora genotypes were evaluated in Experiment 1 (November 2013). In Experiment 2 (December 2014), in addition to the previous characteristics, gas exchange, photochemical efficiency, leaf water potential, and leaf hydraulic conductivity were investigated in five genotypes. No significant differences were observed in specific leaf hydraulic conductance, stomatal density, or gas exchange. The correlation between root hydraulic conductance and leaf area and dry mass indicates a physiological balance, reflecting the root system's ability to supply water to the aerial parts and maintain leaf water potential and photosynthetic activity during periods of high atmospheric evapotranspiration. These characteristics are important for genotypes cultivated under low water supply and high evaporative demand, even under irrigation.

Cultivated soybean is a globally important crop; understanding its responses to different light spectra within the canopy is essential, especially considering the limited agricultural area. Energy flux and spectral quality are key components of the light environment that determine photosynthesis and, consequently, plant growth. These factors influence the composition and structure of photosystem II, thereby affecting energy partitioning between photochemical and nonphotochemical processes. This study evaluated the photosynthetic performance of two soybean genotypes under four light environments with distinct spectral compositions but equal energy flux. Results showed that PSII efficiency improved by the wavelengths outside the PAR range, irrespective of genotype. However, quantum yield parameters revealed genotype-specific responses under blue and red light. Plants exposed exclusively to red light exhibited reduced photosynthetic efficiency and increased photodamage after prolonged exposure, consistent with red light syndrome.

Ensuring global food security requires noninvasive techniques for optimizing resource use and monitoring crop health. Hyperspectral imaging (HSI) enables the precise analysis of plant physiology by capturing spectral data across narrow bands. This review explores HSI's role in agriculture, particularly its integration with unmanned aerial vehicles, AI-driven analytics, and machine learning. These advancements allow real-time monitoring of photosynthesis, chlorophyll fluorescence, and carbon assimilation, linking spectral data to plant health and agronomic decisions. Key indicators such as solar-induced fluorescence and vegetation indices enhance crop stress detection. This work compares HSI-derived metrics in differentiating nutrient deficiencies, drought, and disease. Despite its potential, challenges remain in data standardization and spectral interpretation. This review discusses solutions such as molecular phenotyping and predictive modeling, for AI-driven precision agriculture. Addressing these gaps, HSI is poised to revolutionize farming, improve climate resilience, and ensure food security.

The following scientific autobiography is presented here as a homage to Professor Kazuo Shibata, who is the one who led me to do research in photosynthesis. He had invited me to Riken (The Institute of Physical and Chemical Research), and had launched the Japan-US Collaboration Project on "The Solar Energy Conversion by Means of Photosynthesis" and had invited many international scientists to Riken. My research, under Shibata, started on using a sensitive method for the determination of chlorophyll b, and of SDS-PAGE for the pigment protein complexes of the two photosystems. After Shibata had passed away at the age of 66, I found post-illumination CO₂ burst from cyanobacterial cell suspensions. This finding led me to study the CO₂-concentrating mechanism (CCM) and the function and structure of NADP(H) dehydrogenase complexes (NDH-I) in cyanobacteria, which were developed after I had moved to Nagoya University, and in several other laboratories in the world after I had retired from Nagoya University.

Herein, we report on the 2025 Gordon Research Conference (27 July-1 August) and its preceding Gordon Research Seminar (26-27 July) on Photosynthesis, entitled "Mechanisms of the Process Driving the Biosphere Through the Lenses of Experiment and Computation". Both were held at Sunday River Resort in Newry, Maine, USA. The seminar and conference brought together an international group of photosynthesis researchers to discuss the most cutting-edge work uncovering photosynthetic mechanisms via computation, genetic manipulation, systems biology, structural biology, and much more.

Potato tuber greening occurs due to the chlorophyll accumulation upon exposure to light, however, fundamental information on tuber chlorophyll metabolism is lacking. We measured the effect of varying light exposure (0, 48, 96, and 168 h) on chlorophyll concentration and gene expression of enzymes in the chlorophyll metabolic pathway in the potato varieties that differ in greening propensity. Greening was associated with the upregulation of genes involved in chlorophyll biosynthesis, particularly glutamyl-tRNA reductase 1, magnesium-chelatase subunit H, and magnesium-protoporphyrin IX monomethyl ester cyclase, and downregulation of genes involved in chlorophyll cycling and degradation, including chlorophyllide a oxygenase, and pheophorbide a oxygenase. Our findings suggest that relative resistance to tuber greening propensity may be due to a weaker upregulation of chlorophyll biosynthesis genes and weaker downregulation of chlorophyll degradation genes that occurs in susceptible varieties. The association of these biosynthesis and degradation genes with greening susceptibility may provide possible breeding targets for the future development of more greening-resistant varieties.

Strobilurin fungicides, such as pyraclostrobin (PCL), can impact plant metabolism and morphophysiological parameters. This study evaluated the effects of PCL on Phaseolus vulgaris L., subjecting seeds to imbibition in different concentrations (0, 112, 450; and 1,800 mg L^-1) for 10 and 30 min. After germination in a growth chamber, germination, growth, biomass, anatomical, and physiological characteristics were analyzed. The study confirmed that PCL interference was proportional to the concentration and seed imbibition time, affecting the percentage of germinated seeds in the first count, normal and abnormal seedlings, and dead seeds. There was a reduction in seedling growth and metaxylem diameter, resulting in lower biomass accumulation. However, lower concentrations (0 and 112 mg L^-1) favored the effective photochemical activity of PSII. We concluded that PCL influences seedling germination, anatomy, and physiology, with reduced concentrations potentially beneficial.

The strategies of Norway spruce [Picea abies (L.) Karst.] to increasing atmospheric CO₂ concentration (C_a) are not entirely clear. Here, we reconstructed centennial trajectories of leaf internal CO₂ concentration (C_i) and intrinsic water-use efficiency (WUE_i) from the amount of ¹³C in tree-ring cellulose. We collected 57 cores across elevations, soil, and atmospheric conditions in central Europe. Generally, WUE_i and C_i increased over the last 100 years and the C_i/C_a ratio remained almost constant. However, two groups were distinguished. The first group showed a quasi-linear response to C_a and the sensitivity of C_i to C_a (s = dC_i/dC_a) ranged from 0 to 1. Trees in the second group showed nonmonotonic responses with extremes during the peak of industrial air pollution in the 1980s and s increase from -1 to +1.6. Our study shows a marked attenuation of the rise in WUE_i during the 20^th century leading to invariant WUE_i in recent decades.

Understanding stress responses of endangered plants is vital for their conservation under climate change. We examined the effects of iso-osmotic drought (PEG) and salinity (NaCl) on the growth and physiology of three populations of the critically endangered legume Onobrychis conferta subsp. conferta (OC1, OC2, OC3) endemic to North-Western Tunisia. Both stresses reduced photosynthesis, stomatal conductance, intercellular CO₂, and carboxylation efficiency, while increasing intrinsic water-use efficiency. PSII photoinhibition (F_v/F_m decline) occurred after 6 d. Prolonged stress suppressed growth and water content, particularly under salinity, but enhanced root elongation and root-to-shoot ratios in OC1 and OC2. OC3, from dry grasslands, showed higher water retention, photosynthetic efficiency, and adaptive morphology than OC1 (Pinus forest) and OC2 (watercourse edge), highlighting ecotype-dependent tolerance. OC1 exhibited increased root allocation under salinity, exhibiting a salt-avoidance strategy. Identifying resilient ecotypes is crucial for conservation, restoration, and adaptation of O. conferta to increasing drought and salinity.

This study evaluated the efficiency of green manure (+GM) on PSII efficiency throughout the day in Dalbergia ecastophyllum. The experiment was carried out in a disabled clay extraction deposit, located approximately 30 km south of São Mateus city (Espírito Santo State, Brazil). Chlorophyll (Chl) index, Chl a fluorescence, and plant growth were measured in the summer, after 12 months of planting. +GM improved the photochemical performance of D. ecastophyllum, reducing the occurrence of photoinhibition throughout the day. +GM increased the photochemical quantum yield, the probability of a photon absorbed to move beyond quinone Q_A^-, and the total Chl index, resulting in higher plant height and stem diameter (+11.7 and +2.2%, respectively). The number of active reaction centers per cross-section and the performance index of PSII values were unchanged throughout the day. Full recovery of both K and L-bands occurred at night. In contrast, plants growing with -GM had higher energy losses as heat. In conclusion, these results contribute to improving revegetation techniques, to create better conditions for the planting of native tree species in degraded areas.

Metal toxicity in marine ecosystems is a growing issue owing to terrestrial runoff and anthropogenic pollution. Heterocapsa cf. bohaiensis, a newly isolated dinoflagellate from New Caledonia, was cultivated in photobioreactors operating continuously with high concentrations (10^-3 M) of nickel (Ni²⁺) and/or iron (Fe²⁺) and their photosynthetic efficiency was assessed. The photosynthetic measurements indicated that H. cf. bohaiensis was tolerant to Ni²⁺ but sensitive to Fe²⁺ high concentrations. In the presence of Fe²⁺, maximum quantum efficiency and maximal relative electron transport rate decreased from 0.62 to 0.47 and from 156 to 102, respectively. The JIP-tests suggested a reduction of the photosynthesis in response to Fe²⁺ due to a disruption in the electron transport chain rather than a defect in the light absorption and trapping capacity which were on the contrary enhanced by Fe²⁺. These results bring new knowledge on the impact of nickel and iron on microalgae photosynthetic pathways.

We present here a tribute to George E. Hoch, one of the top leaders in deciphering the primary steps of oxygenic photosynthesis. After providing his academic background, we discuss his selected research on the photoreactions of photosynthesis. We end this tribute with reminiscences by Robert S. Knox, Jerome Kaye, and Doris Teichler-Zallen.

Christa Critchley is a distinguished researcher in basic and applied photosynthesis research. Her research has centered on the structure and function of chloroplasts and the application of chlorophyll a fluorescence to understanding the way PSII works. In her research, she used two biophysical tools, Nuclear Magnetic Resonance (NMR) and Chlorophyll (Chl) a fluorescence, as well as several other biochemical and plant physiological methods. Later in her career, she pioneered research in artificial photosynthesis (AP) focusing on the process of light-mediated water splitting and oxygen evolution. Here, only a glimpse of her life and some selected research is included.

Enhancing plant productivity and mitigating the impact of environmental stressors require a thorough understanding of phytomonitoring and physiological features indicative of plant health. This study delves into the response of cucumber plants to phosphorus deficiency employing diverse tools to identify key indicators and unravel the underlying mechanisms. Under phosphorus deficiency, a rapid response in older leaves was observed through the analysis of chlorophyll and carotenoid content. Molecular-level changes in photosynthetic performance were found to be age-dependent, as revealed by multidimensional statistical methods, highlighting the interconnectedness of examined features with the experimental setup timing. This can assist in understanding the long-term fluctuations in traits linked to phosphorus deficiency, facilitating early detection of stress.

The impact of salt stress is becoming more prevalent each year, largely due to the effects of climate change. Limited availability of salt-free water is rising concern for hydroponics lettuce production. Despite evidence supporting salt stress-induced quality losses and physiological changes, studies on romaine lettuce salt-stress tolerance are limited. This study examined the mechanism underlying the sodium chloride (NaCl) tolerance (0, 50, 100, and 150 mM) of lettuce on its growth and nutrition at late-rosette and early head-formation stages. Results revealed 76% fresh mass reduction under increased NaCl at both stages. The study also found unchanged carbon assimilation with reduced stomatal conductance under increased NaCl. Salt-stressed lettuce accumulated more boron and iron but had reduced phosphorus and calcium. Phenolics and sugars increased linearly under salt stress, suggesting that lettuce responds to increased oxidative stress at both stages. A positive association between salt treatment and sodium to potassium ion ratio indicated lettuce sensitivity to salt stress at both stages.

Phosphoglycolate phosphatase (PGPase), a key enzyme in photosynthetic organisms, catalyzes the dephosphorylation of phosphoglycolate, which is largely produced by the oxygenase activity of Rubisco, and is a potent inhibitor of several Calvin cycle enzymes. PGPase (CrPGPase 1) was previously cloned, purified, and characterized from unicellular green Chlamydomonas reinhardtii. In silico analysis revealed two more candidates encoding PGPase enzymes in the C. reinhardtii genome. In this study, we isolated, cloned, and overexpressed three PGPase genes (pgp1, pgp2, pgp3) from C. reinhardtii and performed gene expression analysis at high and low ammonium [NH₄⁺] concentrations. We demonstrate that all three pgp genes encode functionally active PGPases in C. reinhardtii. In addition, we show that pgp1 and pgp2 genes are N-responsive genes and are upregulated under low ammonium concentrations. In silico analysis revealed that PGPase exists mainly in three isoforms in higher plants and algae.

Winter oilseed rape (Brassica napus L.), the principal oilseed crop in Europe, is notably vulnerable to spring frosts that can drastically reduce yields in ways that are challenging to predict with standard techniques. Our research focused on evaluating the efficacy of photosynthetic efficiency analysis in this crop and identifying specific chlorophyll fluorescence parameters severely impacted by frost, which could serve as noninvasive biomarkers for yield decline. The experiments were carried out in semi-controlled conditions with several treatments: a control, one day at -3°C, three days at -3°C, one day at -6°C, and three days at -6°C. We employed continuous-excitation and pulse-amplitude-modulation chlorophyll fluorescence measurements to assess plant sensitivity to frost. Also, plant gas exchange and chlorophyll content index measurements were performed. Certain parameters strongly correlated with final yield losses, thereby establishing a basis for developing new agricultural protocols to predict and mitigate frost damage in rapeseed crops accurately.