Photosynthetic Structures Research Articles

Instantaneous growth: a compact measure of efficient carbon and nitrogen allocation in leaves and roots of C3 and C4 plants.

Elucidating plant functions and identifying crop productivity bottlenecks requires the accurate quantification of their performance. This task has been attained through photosynthetic models. However, their traditional focus on the leaf's capacity to uptake CO2 is becoming increasingly restrictive. Advanced bioengineering of C3 plants has made it possible to increase rates of CO2 assimilation by packing photosynthetic structures more densely within leaves. The operation of mechanisms that concentrate CO2 inside leaves can boost rates of assimilation while requiring a lower investment in carboxylating enzymes. Therefore, whether in the context of spontaneous plants or modern manipulation, considering trade-offs in resource utilization efficiency emerges as a critical necessity. I've developed a concise and versatile analytical model that simulates concurrent leaf and root growth by balancing instantaneous fluxes of carbon and nitrogen. Carbon is made available by leaf photosynthesis, encompassing all types of biochemistries, while nitrogen is either taken up by roots or remobilized after senescence. The allocation of leaf nitrogen between light or carbon reactions was determined using a fitting algorithm: growth maximisation was the only reliable fitting goal. Both the leaf nitrogen pool and the root-to-leaf ratio responded realistically to various environmental drivers (CO2 concentration, light intensity, soil nitrogen), replicating trends typically observed in plants. Furthermore, modifying the strength of CO2 concentrating mechanisms proved sufficient to alter the root-to-leaf ratio between C3 and C4 types. This direct and mechanistic one-to-one link convincingly demonstrates, for the first time, the functional dependence of a morphological trait on a single biochemical property.

Superoxide Dismutase Premodulates Oxidative Stress in Plastids for Protection of Tobacco Plants from Cold Damage Ultrastructure Damage

ROS-dependent induction of oxidative damage can be used as a trigger initiating genetically determined non-specific protection in plant cells and tissues. Plants are potentially able to withstand various specific (toxic, osmotic) factors of abiotic effects, but do not have sufficient or specific sensitivity to form an adequate effective response. In this work, we demonstrate one of the possible approaches for successful cold acclimation through the formation of effective protection of photosynthetic structures due to the insertion of the heterologous FeSOD gene into the tobacco genome under the control of the constitutive promoter and equipped with a signal sequence targeting the protein to plastid. The increased enzymatic activity of superoxide dismutase in the plastid compartment of transgenic tobacco plants enables them to tolerate the oxidative factor of environmental stresses scavenging ROS. On the other hand, the cost of such resistance is quite high and, when grown under normal conditions, disturbs the arrangement of the intrachloroplastic subdomains leading to the modification of stromal thylakoids, probably significantly affecting the photosynthesis processes that regulate the efficiency of photosystem II. This is partially compensated for by the fact that, at the same time, under normal conditions, the production of peroxide induces the activation of ROS detoxification enzymes. However, a violation of a number of processes, such as the metabolism of accumulation, and utilization and transportation of sugars and starch, is significantly altered, which leads to a shift in metabolic chains. The expected step for further improvement of the applied technology could be both the use of inducible promoters in the expression cassette, and the addition of other genes encoding for hydrogen peroxide-scavenging enzymes in the genetic construct that are downstream in the metabolic chain.

Effects of Exogenous Melatonin on the Growth and Physiological Characteristics of Ginkgo biloba L. under Salinity Stress Conditions

Ginkgo (Ginkgo biloba L.) is a cherished relic among plants, commonly planted as a street tree. However, it faces cultivation challenges due to escalating soil salinization and widespread snowmelt application. Therefore, this study used 4-year-old Ginkgo seedlings to investigate how exogenous melatonin at varying concentrations affects seedling growth and physiology under salinity stress. The results revealed that appropriate melatonin concentrations (0.02, 0.1 mmol·L−1) significantly mitigated leaf yellowing under different NaCl stress levels. Furthermore, they increased ground diameter, current-year branch growth, relative water concentration, free proline, and soluble sugars in leaves. Melatonin also reduced electrolyte exudation rates, flavonoids, and malonic dialdehyde concentration, while enhancing peroxidase and superoxide dismutase activities. This led to reduced chlorophyll content, photosynthetic rate, stomatal conductance, and transpiration rate, stabilizing intercellular CO2 concentration, preserving photosynthetic structures, and enhancing photosynthetic rates. Additionally, the decline in the photosynthetic electron transport rate, the effective photochemical quantum yield of PSII, and the potential efficiency of primary conversion of light energy of PSII was alleviated. Minimal fluorescence and the non-photochemical quenching coefficient also improved. However, high melatonin concentration (0.5 mmol·L−1) exacerbated salinity stress. After analyzing composite scores, the 0.02 mmol·L−1 melatonin treatment was most effective in alleviating NaCl stress, while the 0.5 mmol·L−1 treatment intensified physiological stress under 200 mmol·L−1 NaCl stress. Principal component analysis and correlation analysis identified seven physiological indicators (photosynthetic rate, transpiration rate, photosynthetic electron transport rate, minimal fluorescence, superoxide dismutase, free proline, and chlorophyll a) and three growth indicators (ground diameter, branch length, and current-year branch thickness) as key markers for rapid salinity stress assessment in Ginkgo. These findings are crucial for addressing challenges associated with snowmelt’s impact on roadside Ginkgo trees, expanding planting areas, and breeding exceptional salt-tolerant Ginkgo varieties.

Role of Photosynthesis Processes in the Dynamics of the Plant Community

The dynamics of the main photosynthetic structures are studied by mathematical modeling methods in this work. Chlorophyll portion variability in phytoplankton and formation of energy-intensive substances in the process of photosynthesis underlie the models. These cellular components are considered in terms of their participation in the growth of specific biomass. Computational experiments are conducted to simulate various degrees of environmental friendliness. The corresponding functions are built in accordance with seasonal fluctuations throughout the year in the Far East region of Russia. The stability of model solutions in long-term dynamics is also investigated. The models are tested for biological adequacy, and their effectiveness is compared. For the model selected as a result of the comparison, the optimal control problem was formulated and solved. This way reduces the space of the initial components of the model system. The main conclusion is that a step-by-step description of photosynthetic transformations gives a result close to the experimental description of phytoplankton production dynamics.

Advanced Microscopy Techniques for Molecular Biophysics.

Though microscopy is most often intended as a technique for providing qualitative assessment of cellular and subcellular properties, when coupled with other instruments such as wavelength selectors, lasers, photoelectric devices and computers, it can perform a wide variety of quantitative measurements, which are demanding in establishing relationships between the properties and structures of biological material in all their spatial and temporal complexities. These combinations of instruments are a powerful approach to improve non-destructive investigations of cellular and subcellular properties (both physical and chemical) at a macromolecular scale resolution. Since many subcellular compartments in living cells are characterized by structurally organized molecules, this review deals with three advanced microscopy techniques well-suited for these kind of investigations, i.e., microspectrophotometry (MSP), super-resolution localization microscopy (SRLM) and holotomographic microscopy (HTM). These techniques can achieve an insight view into the role intracellular molecular organizations such as photoreceptive and photosynthetic structures and lipid bodies play in many cellular processes as well as their biophysical properties. Microspectrophotometry uses a set-up based on the combination of a wide-field microscope and a polychromator, which allows the measurement of spectroscopic features such as absorption spectra. Super resolution localization microscopy combines dedicated optics and sophisticated software algorithms to overcome the diffraction limit of light and allow the visualization of subcellular structures and dynamics in greater detail with respect to conventional optical microscopy. Holotomographic microscopy combines holography and tomography techniques into a single microscopy set-up, and allows 3D reconstruction by means of the phase separation of biomolecule condensates. This review is organized in sections, which for each technique describe some general aspects, a peculiar theoretical aspect, a specific experimental configuration and examples of applications (fish and algae photoreceptors, single labeled proteins and endocellular aggregates of lipids).

Ectothiorhodospira lacustris sp. nov., a New Purple Sulfur Bacterium from Low-Mineralized Soda Lakes That Contains a Unique Pathway for Nitric Oxide Reduction

Several strains of a Gram-negative, anaerobic photoautotrophic, motile, rod-shaped bacterium, designated as B14B, A-7R, and A-7Y were isolated from biofilms of low-mineralized soda lakes in central Mongolia and Russia (southeast Siberia). They had lamellar stacks as photosynthetic structures and bacteriochlorophyll a as the major photosynthetic pigment. The strains were found to grow at 25–35 °C, pH 7.5–10.2 (optimum, pH 9.0), and with 0–8% (w/v) NaCl (optimum, 0%). In the presence of sulfide and bicarbonate, acetate, butyrate, yeast extract, lactate, malate, pyruvate, succinate, and fumarate promoted growth. The DNA G + C content was 62.9–63.0 mol%. While the 16S rRNA gene sequences confirmed that the new strains belonged to the genus Ectothiorhodospira of the Ectothiorhodospiraceae, comparison of the genome nucleotide sequences of strains B14B, A-7R, and A-7Y revealed that the new isolates were remote from all described Ectothiorhodospira species both in dDDH (19.7–38.8%) and in ANI (75.0–89.4%). The new strains are also genetically differentiated by the presence of a nitric oxide reduction pathway that is lacking from all other Ectiothiorhodospiraceae. We propose to assign the isolates to the new species, Ectothiorhodospira lacustris sp. nov., with the type strain B14BT (=DSM 116064T = KCTC 25542T = UQM 41491T).

Salt Stress Inhibits Photosynthesis and Destroys Chloroplast Structure by Downregulating Chloroplast Development-Related Genes in Robinia pseudoacacia Seedlings.

Soil salinization is an important factor limiting food security and ecological stability. As a commonly used greening tree species, Robinia pseudoacacia often suffers from salt stress that can manifest as leaf yellowing, decreased photosynthesis, disintegrated chloroplasts, growth stagnation, and even death. To elucidate how salt stress decreases photosynthesis and damages photosynthetic structures, we treated R. pseudoacacia seedlings with different concentrations of NaCl (0, 50, 100, 150, and 200 mM) for 2 weeks and then measured their biomass, ion content, organic soluble substance content, reactive oxygen species (ROS) content, antioxidant enzyme activity, photosynthetic parameters, chloroplast ultrastructure, and chloroplast development-related gene expression. NaCl treatment significantly decreased biomass and photosynthetic parameters, but increased ion content, organic soluble substances, and ROS content. High NaCl concentrations (100-200 mM) also led to distorted chloroplasts, scattered and deformed grana lamellae, disintegrated thylakoid structures, irregularly swollen starch granules, and larger, more numerous lipid spheres. Compared to control (0 mM NaCl), the 50 mM NaCl treatment significantly increased antioxidant enzyme activity while upregulating the expression of the ion transport-related genes Na+/H+ exchanger 1(NHX 1) and salt overly sensitive 1 (SOS 1) and the chloroplast development-related genes psaA, psbA, psaB, psbD, psaC, psbC, ndhH, ndhE, rps7, and ropA. Additionally, high concentrations of NaCl (100-200 mM) decreased antioxidant enzyme activity and downregulated the expression of ion transport- and chloroplast development-related genes. These results showed that although R. pseudoacacia can tolerate low concentrations of NaCl, high concentrations (100-200 mM) can damage chloroplast structure and disturb metabolic processes by downregulating gene expression.

Effects of bulk and nano-ZnO particles on functioning of photosynthetic apparatus in barley (Hordeum vulgare L.)

The functioning of the photosynthetic apparatus in barley (Hordeum vulgare L.) after 7-days of exposure to bulk (b-ZnO) and nanosized ZnO (n-ZnO) (300, 2000, and 10,000 mg/l) has been investigated. An impact on the amount of chlorophylls, photosynthetic efficiency, as well as the zinc accumulation in chloroplasts was demonstrated. Violation of the chloroplast fine structure was revealed. These changes were generally more pronounced with n-ZnO exposure, especially at high concentrations. For instance, the chlorophyll deficiency under 10,000 mg/l b-ZnO treatment was 31% and with exposure to 10,000 mg/l n-ZnO, the chlorophyll deficiency was already 52%. The expression analysis of the photosynthetic genes revealed their different sensitivity to b-ZnO and n-ZnO exposure. The genes encoding subunits of photosystem II (PSII) and, to a slightly lesser extent, photosystem I (PSI) showed the highest suppression of transcriptional levels. The mRNA levels of the subunits of cytochrome-b6f, NADH dehydrogenase, ribulose-1,5-bisphosphate carboxylase and ATP synthase, which, in addition to linear electron flow (LEF), participate in cyclic electron flow (CEF) and autotrophic CO2 fixation, were more stable or increased under b-ZnO and n-ZnO treatments. At the same time, CEF was increased. It was assumed that under the action of b-ZnO and n-ZnO, the processes of LEF are disrupted, and CEF is activated. This allows the plant to prevent photo-oxidation and compensate for the lack of ATP for the CO2 fixation process, thereby ensuring the stability of photosynthetic function in the initial stages of stress factor exposure. The study of photosynthetic structures of crops is important from the point of view of understanding the risks of reducing the production potential and the level of food security due to the growing use of nanoparticles in agriculture.

Single-walled carbon nanotubes protect photosynthetic reactions in Chlamydomonas reinhardtii against photoinhibition

Single-walled carbon nanotubes (SWCNTs) are among the most exploited carbon allotropes in nanosensing, bioengineering, and photobiological applications, however, the interactions of nanotubes with the photosynthetic process and structures are still poorly understood. We found that SWCNTs are not toxic to the photosynthetic apparatus of the model unicellular alga Chlamydomonas reinhardtii and demonstrate that this carbon nanomaterial can protect algal photosynthesis against photoinhibition. The results show that the inherent phytotoxicity of the nanotubes may be overcome by an intentional selection of nanomaterial characteristics. A low concentration (2 μg mL−1) of well-dispersed, purified and small SWCNTs did not alter the growth and pigment accumulation of the cultures. Indeed, under the photoinhibitory conditions of our experiments, SWCNT-enriched samples were characterized by a lower rate of PSII inactivation, reduced excitation pressure in PSII, a higher rate of photosynthetic electron transport, and an increased non-photochemical quenching in comparison with the controls. In addition, SWCNTs change the distribution of energy between the photosystems in favour of PSII (state 1). The underlying mechanism of this action is not yet understood but possibly, electrons or energy can be exchanged between the redox active nanotubes and photosynthetic components, and probably other redox active intra-chloroplast constituents. Alternatively, nanotubes may promote the formation of an NPQ conformation of PSII. Our results provided evidence for such electron/energy transfer from photosynthetic structures toward the nanotubes. The discovered photoprotective effects can potentially be used in photobiotechnology to maintain the photosynthetic activity of microorganisms under unfavourable conditions.

Diversity of responses to nitrogen deficiency in distinct wheat genotypes reveals the role of alternative electron flows in photoprotection.

Nitrogen (N) deficiency represents an important limiting factor affecting photosynthetic productivity and the yields of crop plants. Significant reported differences in N use efficiency between the crop species and genotypes provide a good background for the studies of diversity of photosynthetic and photoprotective responses associated with nitrogen deficiency. Using distinct wheat (Triticum aestivum L.) genotypes with previously observed contrasting responses to nitrogen nutrition (cv. Enola and cv. Slomer), we performed advanced analyses of CO2 assimilation, PSII, and PSI photochemistry, also focusing on the heterogeneity of the stress responses in the different leaf levels. Our results confirmed the loss of photosynthetic capacity and enhanced more in lower positions. Non-stomatal limitation of photosynthesis was well reflected by the changes in PSII and PSI photochemistry, including the parameters derived from the fast-fluorescence kinetics. Low photosynthesis in N-deprived leaves, especially in lower positions, was associated with a significant decrease in the activity of alternative electron flows. The exception was the cyclic electron flow around PSI that was enhanced in most of the samples with a low photosynthetic rate. We observed significant genotype-specific responses. An old genotype Slomer with a lower CO2 assimilation rate demonstrated enhanced alternative electron flow and photorespiration capacity. In contrast, a modern, highly productive genotype Enola responded to decreased photosynthesis by a significant increase in nonphotochemical dissipation and cyclic electron flow. Our results illustrate the importance of alternative electron flows for eliminating the excitation pressure at the PSII acceptor side. The decrease in capacity of electron acceptors was balanced by the structural and functional changes of the components of the electron transport chain, leading to a decline of linear electron transport to prevent the overreduction of the PSI acceptor side and related photooxidative damage of photosynthetic structures in leaves exposed to nitrogen deficiency.

Biocircuits in plants and eukaryotic algae.

As one of synthetic biology’s foundations, biocircuits are a strategy of genetic parts assembling to recognize a signal and to produce a desirable output to interfere with a biological function. In this review, we revisited the progress in the biocircuits technology basis and its mandatory elements, such as the characterization and assembly of functional parts. Furthermore, for a successful implementation, the transcriptional control systems are a relevant point, and the computational tools help to predict the best combinations among the biological parts planned to be used to achieve the desirable phenotype. However, many challenges are involved in delivering and stabilizing the synthetic structures. Some research experiences, such as the golden crops, biosensors, and artificial photosynthetic structures, can indicate the positive and limiting aspects of the practice. Finally, we envision that the modulatory structural feature and the possibility of finer gene regulation through biocircuits can contribute to the complex design of synthetic chromosomes aiming to develop plants and algae with new or improved functions.

Selection of drought-tolerant tomato during the vegetative stage

Drought stress consists of a significant productivity constraint in tomatoes. Two contrasting crosses were performed to estimate physiological and morphological traits in response to drought stress during the vegetative stage, aiming to identify superior genotypes for drought tolerance. Two genotypes (GBT_2037 – sensitive drought-sensitive and GBT_2016 – intermediate drought-tolerant) were used as female parentals, and a commercial hybrid (drought tolerant) was used as a pollen source in both crosses: C1 (GBT_2037 × Commercial hybrid) and C2 (GBT_2016 × Commercial hybrid). The populations of parentals (P), the first generation of descendants (F1), backcrosses (BC), and the second generation of self-pollination (F2) were exposed to drought stress for 20 days when they were analyzed: physiological traits (relative water content of leaves, proline, and relative chlorophyll content) and morphological (plant height, stem diameter, number of leaves, fresh and dry matter of roots and shoot and classification by wilt scale). The means of chlorophyll, root/shoot ratio, and water content in leaves for the F2 generation of C2 were higher than C1, indicating that C2 resulted in plants with greater capacity to maintain turgor under conditions of water stress and presented minor damage to the photosynthetic structures, consequently showing greater tolerance to drought stress.

Assessment of the Photosynthetic Apparatus Functions by Chlorophyll Fluorescence and P700 Absorbance in C3 and C4 Plants under Physiological Conditions and under Salt Stress.

Functions of the photosynthetic apparatus of C3 (Pisum sativum L.) and C4 (Zea mays L.) plants under physiological conditions and after treatment with different NaCl concentrations (0–200 mM) were investigated using chlorophyll a fluorescence (pulse-amplitude-modulated (PAM) and JIP test) and P700 photooxidation measurement. Data revealed lower density of the photosynthetic structures (RC/CSo), larger relative size of the plastoquinone (PQ) pool (N) and higher electron transport capacity and photosynthetic rate (parameter RFd) in C4 than in C3 plants. Furthermore, the differences were observed between the two studied species in the parameters characterizing the possibility of reduction in the photosystem (PSI) end acceptors (REo/RC, REo/CSo and δRo). Data revealed that NaCl treatment caused a decrease in the density of the photosynthetic structures and relative size of the PQ pool as well as decrease in the electron transport to the PSI end electron acceptors and the probability of their reduction as well as an increase in the thermal dissipation. The effects were stronger in pea than in maize. The enhanced energy losses after high salt treatment in maize were mainly from the increase in the regulated energy losses (ΦNPQ), while in pea from the increase in non-regulated energy losses (ΦNO). The reduction in the electron transport from QA to the PSI end electron acceptors influenced PSI activity. Analysis of the P700 photooxidation and its decay kinetics revealed an influence of two PSI populations in pea after treatment with 150 mM and 200 mM NaCl, while in maize the negligible changes were registered only at 200 mM NaCl. The experimental results clearly show less salt tolerance of pea than maize.

Developmental Analysis of Compound Leaf Development in Arachis hypogaea.

Leaves are the primary photosynthetic structures, while photosynthesis is the direct motivation of crop yield formation. As a legume plant, peanut (Arachis hypogaea) is one of the most economically essential crops as well as an important source of edible oil and protein. The leaves of A. hypogaea are in the tetrafoliate form, which is different from the trifoliate leaf pattern of Medicago truncatula, a model legume species. In A. hypogaea, an even-pinnate leaf with a pair of proximal and distal leaflets was developed; however, only a single terminal leaflet and a pair of lateral leaflets were formed in the odd-pinnate leaf in M. truncatula. In this study, the development of compound leaf in A. hypogaea was investigated. Transcriptomic profiles revealed that the common and unique differentially expressed genes were identified in a proximal leaflet and a distal leaflet, which provided a research route to understand the leaf development in A. hypogaea. Then, a naturally occurring mutant line with leaf developmental defects in A. hypogaea was obtained, which displayed a pentafoliate form with an extra terminal leaflet. The characterization of the mutant indicated that cytokinin and class I KNOTTED-LIKE HOMEOBOX were involved in the control of compound leaf pattern in A. hypogaea. These results expand our knowledge and provide insights into the molecular mechanism underlying the formation of different compound leaf patterns among species.

تأثیر کتیرا روی برخی خصوصیات مورفوفیزیولوژیک و مرتبط با عملکرد دانه گیاه سیاهدانه (Nigella sativa L.) تحت شرایط خشکی

Introduction In fact, drought is stress that restricts the plant photosynthesis and causing changes in the chlorophyll content and damage to photosynthetic structures. One of the important reasons that environmental stresses such as drought reduce the growth and photosynthesis ability of the plant is a disturbance in the balance between production and removal of free oxygen radicals. Transpiration is a necessary process for photosynthesis and growth of plants but depending on the conditions may be harmful in some cases, so that the use of anti-transpirant can be one of the most effective methods for reducing the amount of water lost through transpiration and effective way to reduce the effects of drought stress on plants and adjustment the reduction of the yield due to water deficiency in arid and semi-arid regions. Climate change created in the world and the intensification of stresses caused by it, especially drought stress in arid and semi-arid regions such as Iran, make it difficult to achieve this goal. Therefore, finding strategies that can reduce the effects of water shortages on plant growth and yield and improve growth and yield can be very important. The aim of the present study was to investigate the effect of irrigation regimes and application of different concentrations of tragacanth (naturally dried exudate from some Astragalus species) on black cumin plant. Materials and Methods This research was carried out in a factorial experiment based on completely randomized design with three replications in a greenhouse of the Agriculture College of Kurdistan University in 2018. The experimental factors were including irrigation at three levels of 100% (full irrigation), 70% (mild drought stress), and 40% (severe drought stress) of field capacity of soil and spraying with tragacanth extract at six concentrations of 0, 1.25, 2.5, 5, 7.5, and 10 g/L. Spraying of this material was done using a back sprayer (Shark model) with a constant pressure of 2.4 bar and a volume of 250 liters of water per hectare. Before the data were analyzed, their normality test was performed using the Mini Tab software. After ensuring the normality of data, analysis of variance was performed using SAS ver. 9.3. LSD (Least significant difference) was used to compare the mean of treatments. The graphs are drawn using Excel software. Results and Discussion The results showed that increased drought stress intensity (irrigation reduction) led to the reduced leaf relative water content, Total chlorophyll content, efficiency of photosystem II, plant hight, number of capsules per plant, mean number of seeds per plant, biological yield and grain yield. The positive effects of tragacanth consumption on reducing and modifying the effects of drought stress on different levels of irrigation and different concentrations of tragacanth were different. In the present study, under full irrigation conditions, lower concentrations of tragacanth were useful, while in drought stress conditions, higher concentrations of tragacanth (except 10 g/L) were useful. In full irrigation, the concentration of 1.25 g/L was positive for all studied traits. In mild drought stress, the use of higher concentrations of tragacanth up to 5 g/L had the best effect and more concentrations resulted in a reverse effect on studied traits. In severe drought stress, the use of more concentrations of tragacanth extract was beneficial and improved the studied traits up to 7.5 g/L, but 10 g/L had a negative effect on these traits. Considering the effect of proper concentration of this material on the improvement of measured traits and increasing the grain yield compared to non-application of tragacanth under severe and moderate drought stress conditions by 11.6% and 28.2%, respectively. Conclusion The results of this study indicated the different effects of various concentrations of tragacanth material in different levels of irrigation on studied traits of black cumin. Therefore, it can be concluded that the application of different concentrations of tragacanth gum was completely dependent on the plant's water status. So that, using higher concentrations of tragacanth gum in drought stress conditions had a more positive effect on the plant, and vice versa, using a lower concentration of this material was useful in full irrigation. The effect of tragacanth gum on reducing and modifying the effects of drought stress in different plants requires further studies and extensive research. Tragacanth gum can be introduced as a new anti-transpirant agent with natural origin and its application can be useful and recommended in areas exposed to drought stress.

Next-Generation Proteomics Reveals a Greater Antioxidative Response to Drought in Coffea arabica Than in Coffea canephora

Drought is a major threat to coffee, compromising the quality and quantity of its production. We have analyzed the core proteome of 18 Coffea canephora cv. Conilon Clone 153 and C. arabica cv. Icatu plants and assessed their responses to moderate (MWD) and severe (SWD) water deficits. Label-free quantitative shotgun proteomics identified 3000 proteins in both genotypes, but less than 0.8% contributed to ca. 20% of proteome biomass. Proteomic changes were dependent on the severity of drought, being stronger under SWD and with an enrolment of different proteins, functions, and pathways than under MWD. The two genotypes displayed stress-responsive proteins under SWD, but only C. arabica showed a higher abundance of proteins involved in antioxidant detoxification activities. Overall, the impact of MWD was minor in the two genotypes, contrary to previous studies. In contrast, an extensive proteomic response was found under SWD, with C. arabica having a greater potential for acclimation/resilience than C. canephora. This is likely supported by a wider antioxidative response and an ability to repair photosynthetic structures, being crucial to develop new elite genotypes that assure coffee supply under water scarcity levels.

Effects of sand burial in integrated clonal systems of the invasive Carpobrotus edulis

ABSTRACT Sand burial represents one of the most common stresses for plant performance in coastal sand dunes. Clonal plants inhabiting sand dunes frequently experience situations in which the sand can bury part of the clone while other modules remain unburied. Here we present a field experiment in a coastal sand dune testing the effect of sand burial in the clonal Carpobrotus edulis. In the experiment, apical ramets were either or not subjected to burial in sand to a depth of 90% ramet height, and connected basal ramets were not subjected to sand burial. Sand burial significantly reduced survival and growth of apical ramets. Interestingly, we found a non-local plastic response in basal ramets that was dependent on the conditions experienced by their apical ramets. Thus, when apical ramets remained unburied a developmentally programmed division of labour was found. In this situation, basal ramets specialized in the acquisition of soil-based resources while apical ramets specialized in aboveground expansion. On the contrary, when apical ramets were subjected to sand burial, basal ramets increased the production of photosynthetic structures. This response could alleviate the light stress suffered by the buried apical ramets. We demonstrate that burial stress suffered by apical ramets of C. edulis triggered a compensatory response in their connected unburied ramets. This result highlights the importance of considering modular plasticity to understand plant responses to sand burial stress.

Reaffirming the phyllocladoid affinities ofHuncocladus laubenfelsii(Podocarpaceae) from the early Eocene of Patagonia: a comment on Dörkenet al. (2021)

AbstractWe discuss a recent assessment by Dörken et al. (2021) regarding the affinities of the Eocene fossil species Huncocladus laubenfelsii from Laguna del Hunco (Patagonia, Argentina). We originally (Andruchow-Colombo et al., 2019) assigned this species to the conifer family Podocarpaceae as the first certain South American macrofossil record of the phyllocladoid lineage (Huncocladus+Phyllocladus), based on a combination of numerous macro- and micromorphological vegetative characters. However, Dörken et al. (2021) rejected the podocarpaceous affinity of H. laubenfelsii and considered it to be more closely related to the cycad genera Bowenia or Eobowenia. Their assessment was based almost entirely on two cuticular characters, with only superficial consideration of the abundant additional evidence available that included several diagnostic macromorphological features. We review the two characters mentioned by these authors, and other features, and find that their suggestion is contradicted by the available evidence, maintaining our original assignment. Critical characters include presence/absence of a midvein, secondary venation pattern, arrangement and general morphology of the photosynthetic structures, and morphology and disposition of epidermal cells.

Morphological diversity in purple nutsedge from four agro-ecological zones in Ghana

Purple nutsedge (Cyperus rotundus L.) exhibits plasticity and are morphologically different under different conditions. Due to these differences, the weed might respond differently to weed management. Here, we examined the morphological characteristics of purple nutsedge from southern Ghana relative to those reported from other countries and further assessed differences in ecotypes from four agro-ecological zones in Ghana. A total of 46 purple nutsedge samples: 40 samples from 40 communities across the study area and three each from two research stations were used for the study. The plants were multiplied, planted into pots and laid out in Completely Randomized Design with three replications. Qualitative and quantitative assessments were carried out on both underground and aboveground morphological traits of the weed samples. The qualitative traits of the samples generally conformed to those reported in other countries and did not vary significantly between the agro-ecological zones (P > 0.05). The quantitative (growth) parameters showed significant differences among agro-ecological zones (P < 0.05) and were generally smaller than those reported in other countries, suggesting morphological adaptation of the weed in Ghana. Samples from the transitional zone were significantly smaller and this could facilitate easier management of the weed in that area. The principal component analysis gave four latent factors, which mainly pointed to photosynthetic structures and growth characteristics as the major components determining variations in the collection. Cluster analysis gave four clusters (at 0.7 similarity index), which were related neither to their geographic origin nor to the agro-ecological zones.

Bioprinting of Regenerative Photosynthetic Living Materials

AbstractLiving materials, which are fabricated by encapsulating living biological cells within a non‐living matrix, have gained increasing attention in recent years. Their fabrication in spatially defined patterns that are mechanically robust is essential for their optimal functional performance but is difficult to achieve. Here, a bioprinting technique employing environmentally friendly chemistry to encapsulate microalgae within an alginate hydrogel matrix is reported. The bioprinted photosynthetic structures adopt pre‐designed geometries at millimeter‐scale resolution. A bacterial cellulose substrate confers exceptional advantages to this living material, including strength, toughness, flexibility, robustness, and retention of physical integrity against extreme physical distortions. The bioprinted materials possess sufficient mechanical strength to be self‐standing, and can be detached and reattached onto different surfaces. Bioprinted materials can survive stably for a period of at least 3 days without nutrients, and their life can be further extended by transferring them to a fresh source of nutrients within this timeframe. These bioprints are regenerative, that is, they can be reused and expanded to print additional living materials. The fabrication of the bioprinted living materials can be readily up‐scaled (up to ≥70 cm × 20 cm), highlighting their potential product applications including artificial leaves, photosynthetic bio‐garments, and adhesive labels.