Plant Physiology Research Research Articles

Fluorescence and Hyperspectral Sensors for Nondestructive Analysis and Prediction of Biophysical Compounds in the Green and Purple Leaves of Tradescantia Plants

The application of non-imaging hyperspectral sensors has significantly enhanced the study of leaf optical properties across different plant species. In this study, chlorophyll fluorescence (ChlF) and hyperspectral non-imaging sensors using ultraviolet-visible-near-infrared shortwave infrared (UV-VIS-NIR-SWIR) bands were used to evaluate leaf biophysical parameters. For analyses, principal component analysis (PCA) and partial least squares regression (PLSR) were used to predict eight structural and ultrastructural (biophysical) traits in green and purple Tradescantia leaves. The main results demonstrate that specific hyperspectral vegetation indices (HVIs) markedly improve the precision of partial least squares regression (PLSR) models, enabling reliable and nondestructive evaluations of plant biophysical attributes. PCA revealed unique spectral signatures, with the first principal component accounting for more than 90% of the variation in sensor data. High predictive accuracy was achieved for variables such as the thickness of the adaxial and abaxial hypodermis layers (R2 = 0.94) and total leaf thickness, although challenges remain in predicting parameters such as the thickness of the parenchyma and granum layers within the thylakoid membrane. The effectiveness of integrating ChlF and hyperspectral technologies, along with spectroradiometers and fluorescence sensors, in advancing plant physiological research and improving optical spectroscopy for environmental monitoring and assessment. These methods offer a good strategy for promoting sustainability in future agricultural practices across a broad range of plant species, supporting cell biology and material analyses.

Comprehensive Analysis of Miscanthus Research: Sustainable Biomass and Bioenergy Through Knowledge Mapping

Miscanthus grass species have gained global research attention in the fields of biomass and bioenergy, witnessing remarkable advancements in the 21st century. This study systematically searched and selected relevant literature on primary research involving Miscanthus species, published between 2007 and 2023, from the China National Knowledge Infrastructure and Web of Science core databases. Utilizing CiteSpace as a bibliometric tool, the study generated quantitative statistics and performed data analysis on the selected articles. The examination covered publication trends, national and author publication outputs, author and journal co-citations, keyword research hotspots, and the temporal evolution of research topics in the Miscanthus research field, offering empirical support for future in-depth investigations and innovation in Miscanthus spp. The research findings reveal the following insights: (1) Publication trends can be divided into two phases (stable growth and fluctuating decline), with recent trends maintaining a relatively high level. (2) A collaborative publication network, led by core authors such as Zili Yi, John Clifton-Brown, and Iris Lewandowski, has been established, characterized by a diverse research focus and close cooperation. (3) Research hotspots encompass several aspects, including biomass production yield, efficiency, and energy products of Miscanthus spp., ecological restoration, genetics, plant physiological research, and chemical components. The primary species investigated are Miscanthus×giganteus, Miscanthus sinensis, Miscanthus floridulus, and Miscanthus lutarioriparius.

The Dynamic Assimilation Technique measures photosynthetic CO2 response curves with similar fidelity to steady-state approaches in half the time.

The net CO2 assimilation (A) response to intercellular CO2 concentration (Ci) is a fundamental measurement in photosynthesis and plant physiology research. The conventional A/Ci protocols rely on steady-state measurements and take 15-40 min per measurement, limiting data resolution or biological replication. Additionally, there are several CO2 protocols employed across the literature, without clear consensus as to the optimal protocol or systematic biases in their estimations. We compared the non-steady-state Dynamic Assimilation Technique (DAT) protocol and the three most used CO2 protocols in steady-state measurements, and tested whether different CO2 protocols lead to systematic differences in estimations of the biochemical limitations to photosynthesis. The DAT protocol reduced the measurement time by almost half without compromising estimation accuracy or precision. The monotonic protocol was the fastest steady-state method. Estimations of biochemical limitations to photosynthesis were very consistent across all CO2 protocols, with slight differences in Rubisco carboxylation limitation. The A/Ci curves were not affected by the direction of the change of CO2 concentration but rather the time spent under triose phosphate utilization (TPU)-limited conditions. Our results suggest that the maximum rate of Rubisco carboxylation (Vcmax), linear electron flow for NADPH supply (J), and TPU measured using different protocols within the literature are comparable, or at least not systematically different based on the measurement protocol used.

Plant Growth Regulation in Cell and Tissue Culture In Vitro.

Precise knowledge of all aspects controlling plant tissue culture and in vitro plant regeneration is crucial for plant biotechnologists and their correlated industry, as there is increasing demand for this scientific knowledge, resulting in more productive and resilient plants in the field. However, the development and application of cell and tissue culture techniques are usually based on empirical studies, although some data-driven models are available. Overall, the success of plant tissue culture is dependent on several factors such as available nutrients, endogenous auxin synthesis, organic compounds, and environment conditions. In this review, the most important aspects are described one by one, with some practical recommendations based on basic research in plant physiology and sharing our practical experience from over 20 years of research in this field. The main aim is to help new plant biotechnologists and increase the impact of the plant tissue culture industry worldwide.

Mapping 3D plant chlorophyll distribution from hyperspectral LiDAR by a leaf-canopyradiative transfer model

The three-dimensional (3D) plant chlorophyll distribution plays an essential role in plant physiological and ecological analysis. The hyperspectral LiDAR (HSL) technology, as a new active technology, has the advantage of directly and simultaneously obtaining plant hyperspectral and 3D spatial information. It provides an alternative opportunity for fast and nondestructive 3D plant chlorophyll estimation. Current estimation models are developed by statistical relationships between HSL spectra and plant chlorophyll content, which perform limited robustness and lack physical mechanisms. The leaf-canopy radiative transfer models (RTMs) could describe physical responses between spectra and chlorophyll content, and show great robustness from optical hyperspectral data, which have the potential to overcome the limitation of current estimation models. However, it is unclear whether leaf-canopy RTMs could be applied to HSL spectra for 3D chlorophyll mapping. Therefore, this study explored the potential of a leaf-canopy RTM with HSL spectra for 3D plant chlorophyll estimation. Firstly, an optimal leaf RTM was selected from a series of PROSEPCT models, and determined by estimating leaf-scale chlorophyll content across multi-species and multi-state leaves. Then, the 4SAIL model, a canopy RTM, was optimized to meet the active detection mechanism of the HSL technology. Next, coupling the best PROSPECT with optimized 4SAIL models was used as the leaf-canopy RTM. The 3D chlorophyll distribution was estimated by the leaf-canopy RTM with a lookup table (LUT) algorithm under six cost functions. Finally, the performance of 14 vegetation indice (VI) models was tested as a comparison. Results demonstrated that the PROSPECT-5 model was the best leaf RTM with the best R2 of 0.60. The combination of PROSPECT-5 and optimized 4SAIL model could successfully achieve 3D plant chlorophyll estimation. This leaf-canopy estimation RTM with the best cost function (Least square estimator) had the best accuracy with an R2 of 0.73. Its accuracy was the same as the median accuracy of the best VI model (MTCI model), and higher than that of other VI models. The estimated and actual 3D chlorophyll distributions were consistent. The application of the leaf-canopy RTM with HSL technology offers an alternative approach to plant physiological and ecological research.

Inverting Chlorophyll Content in Jujube Leaves Using a Back-Propagation Neural Network–Random Forest–Ridge Regression Algorithm with Combined Hyperspectral Data and Image Color Channels

Chlorophyll content is highly susceptible to environmental changes, and monitoring these changes can be a crucial tool for optimizing crop management and providing a foundation for research in plant physiology and ecology. This is expected to deepen our scientific understanding of plant ecological adaptation mechanisms, offer a basis for improving agricultural production, and contribute to ecosystem management. This study involved the collection of hyperspectral data, image data, and SPAD data from jujube leaves. These data were then processed using SG smoothing and the isolated forest algorithm, following which eigenvalues were extracted using a combination of Pearson’s phase relationship method and the Partial Least Squares Regression–continuous projection method. Subsequently, seven methods were employed to analyze the results, with hyperspectral data and color channel data used as independent variables in separate experiments. The findings indicated that the integrated BPNN-RF-Ridge Regression algorithm provided the best results, with an R2 of 0.8249, MAE of 2.437, and RMSE of 2.9724. The inclusion of color channel data as an independent variable led to a 3.2% improvement in R2, with MAE and RMSE increasing by 1.6% and 3.9%, respectively. These results demonstrate the effectiveness of integrated methods for the determination of chlorophyll content in jujube leaves and underscore the potential of using multi-source data to improve the model fit with a minimal impact on errors. Further research is warranted to explore the application of these findings in precision agriculture for jujube yield optimization and income-related endeavors, as well as to provide insights for similar studies in other plant species.

The carbon balance of plants: economics, optimization, and trait spectra in a historical perspective.

Over fifty years have passed since the publication of Harold Mooney's formative paper, "The Carbon Balance of Plants" on pages 315-346 of Volume 3 (1972) of Annual Review of Ecology and Systematics. Arguably, the conceptual framework presented in that paper, and the work by Mooney and his students leading up to the paper, provided the foundational principles from which core disciplines emerged in plant economic theory, functional trait theory and, more generally, plant physiological ecology. Here, we revisit the primary impacts of those early discoveries to understand how researchers constructed major concepts in our understanding of plant adaptations, and where those concepts are likely to take us in the near future. The discipline of functional trait ecology, which is rooted in the principles of evolutionary and economic optimization, has captured the imagination of the plant physiological ecology research community, though its emphasis has shifted toward predicting species distributions and ecological roles across resource gradients. In the face of 'big-data' research pursuits that are revealing trait expression patterns at the cellular level and mass and energy exchange patterns at the planetary scale, an opportunity exists to reconnect the principles of plant carbon balance and evolutionary optimization with trait origins at the genetic and cellular scales and trait impacts at the global scale.

Dual-Conductive and Stiffness-Morphing Microneedle Patch Enables Continuous In Planta Monitoring of Electrophysiological Signal and Ion Fluctuation.

The use of conductive microneedles presents a promising solution for achieving high-fidelity electrophysiological recordings with minimal impact on the interfaced tissue. However, a conventional metal-based microneedle suffers from high electrochemical impedance and mechanical mismatch. In this paper, we report a dual-conductive (i.e., both ionic and electronic conductive) and stiffness-morphing microneedle patch (DSMNP) for high-fidelity electrophysiological recordings with reduced tissue damage. The polymeric network of the DSMNP facilitates electrolyte absorption and therefore allows the transition of stiffness from 6.82 to 0.5139 N m-1. Furthermore, the nanoporous conductive polymer increases the specific electrochemical surface area after tissue penetration, resulting in an ultralow specific impedance of 893.13 Ω mm2 at 100 Hz. DSMNPs detect variation potential and action potential in real time and cation fluctuations in plants in response to environmental stimuli. After swelling, DSMNPs mechanically "lock" into biological tissues and prevent motion artifact by providing a stable interface. These results demonstrate the potential of DSMNPs for various applications in the field of plant physiology research and smart agriculture.

Geographical equations of Swertia mussotii bioactivities: evidence from the western Sichuan region of China.

Swertia mussotii is the most authentic raw material used in Tibetan medicine in China for its various bioactivities. This natural medicine resource is at risk of being exhausted due to the double interference of climate change and anthropogenic over-collection. Little is known about habitat characteristics and the crucial environmental factors that influence the levels of active ingredients. The goal of this study is to understand the variability in the bioactive compound content of a wide range of wild S. mussotii as it adapts to changing environmental conditions. The target compound content of the whole plant material was analyzed with the environmental explanatory variables of the field sample sites using a constrained ordination method for their correlation analysis. The results show that 16.3 percent of the sampled wild S. mussotii populations with the highest bioactive content can be grouped into the elite type. The most prominent environmental variables affecting the content of major bioactive products include altitude, aspect, soil TK content, Fe content, and C/N and N/P ratios. Altitude and aspect put indirect effects that are mediated by plant height and density, N/P ratio puts a direct effect, while soil TK content, Fe content and C/N ratio have both direct and indirect effects on the bioactivity of S. mussotii. In addition to the total negative effects of altitude and C/N ratio, the remaining factors play a driving role. These findings demonstrate variation by geographical conditions across S. mussotii accessions for physiologic responses and secondary compounds in wild populations. The knowledge gained from this study can be used for environmental and plant physiology research, efficient collection of naturally active compounds, and conservation strategies for rare natural plant resources.

Global experience in the commercial cultivation of peony flowers: 30 years of research and development

Herbaceous peony is an ancient ornamental and medicinal crop, cultivated for thousands of years in China and Japan. Numerous varieties are popular garden plants in different continents and countries, and recently peony has gained a new reputation as cut flowers. Only in Europe, in last 30 years, trade in cut peony has increased 50-fold. This demand has led to biological research and the development of production technologies. Today, more than 25 countries produce cut peony flowers, with primary markets in Europe, Asia and the USA. However, several factors still restrict peony production - challenges in mass propagation, a complicated flowering physiology, and postharvest handling. Here we summarize the contribution of research in plant physiology to the development of new technologies of peony production and flowering. Further research of molecular and biochemical mechanisms, breeding of new cultivars will contribute to the further development of peony industry. Biotechnological applications and long-term postharvest technologies will facilitate creation of Global Peony Chain for successful marketing of this flower.

StomaAI: an efficient and user-friendly tool for measurement of stomatal pores and density using deep computer vision.

Using microscopy to investigate stomatal behaviour is common in plant physiology research. Manual inspection and measurement of stomatal pore features is low throughput, relies upon expert knowledge to record stomatal features accurately, requires significant researcher time and investment, and can represent a significant bottleneck to research pipelines. To alleviate this, we introduce StomaAI (SAI): a reliable, user-friendly and adaptable tool for stomatal pore and density measurements via the application of deep computer vision, which has been initially calibrated and deployed for the model plant Arabidopsis (dicot) and the crop plant barley (monocot grass). SAI is capable of producing measurements consistent with human experts and successfully reproduced conclusions of published datasets. SAI boosts the number of images that can be evaluated in a fraction of the time, so can obtain a more accurate representation of stomatal traits than is routine through manual measurement. An online demonstration of SAI is hosted at https://sai.aiml.team, and the full local application is publicly available for free on GitHub through https://github.com/xdynames/sai-app.

The History of Plant Physiology at the Immanuel Kant Baltic Federal University

The article reviews the history of plant physiology research at the Immanuel Kant Baltic Federal University from 1969 to this day and analyzes the role of the first and long-time head of the Department of Plant Physiology and Agrochemistry, M. M. Okuntsov, and his pupils, O. A. Ronzhina, G. N.Chupakhina, and A. S. Grebennikov, in the development of these studies. A scientific school led by Okuntsov and focused on non-photosynthetic light-dependent processes in plants had formed by the late 1970s. Presently, physiological research at the University is carried out at the Laboratory of Natural Antioxidants headed by Chupakhina. The Laboratory focuses on the studies of antioxidant system for the purposes of elucidating molecular mechanisms of plant resistance to unfavorable environmental conditions, evaluating plant product quality, and searching for producers of biologically active substances with high antioxidant activity and material for genetic engineering of plants with beneficial traits.

Disclosing the molecular basis of salinity priming in olive trees using proteogenomic model discovery.

Plant responses to salinity are becoming increasingly understood, however, salt priming mechanisms remain unclear, especially in perennial fruit trees. Herein, we showed that low-salt pre-exposure primes olive (Olea europaea) plants against high salinity stress. We then performed a proteogenomic study to characterize priming responses in olive roots and leaves. Integration of transcriptomic and proteomic data along with metabolic data revealed robust salinity changes that exhibit distinct or overlapping patterns in olive tissues, among which we focused on sugar regulation. Using the multi-crossed -omics data set, we showed that major differences between primed and nonprimed tissues are mainly associated with hormone signaling and defense-related interactions. We identified multiple genes and proteins, including known and putative regulators, that reported significant proteomic and transcriptomic changes between primed and nonprimed plants. Evidence also supported the notion that protein post-translational modifications, notably phosphorylations, carbonylations and S-nitrosylations, promote salt priming. The proteome and transcriptome abundance atlas uncovered alterations between mRNA and protein quantities within tissues and salinity conditions. Proteogenomic-driven causal model discovery also unveiled key interaction networks involved in salt priming. Data generated in this study are important resources for understanding salt priming in olive tree and facilitating proteogenomic research in plant physiology.

Electric Impedance Spectroscopy in Trees Condition Analysis: Theory and Experiment.

Electric impedance spectroscopy is an alternative technology to existing methods that shows promising results in the agro-food industry and plant physiology research. For example, this technology makes it possible to monitor the condition of plants, even in the early stages of development, and to control the quality of finished products. However, the use of electric impedance spectroscopy is often associated with the need to organize special laboratory conditions for measurements. Our aim is to extract information about the state of health of the internal tissues of a plant's branches from impedance measurements. Therefore, we propose a new technique using the device and model developed by us that makes it possible to monitor the condition of tree branch tissues in situ. An apple tree was chosen as the object under study, and the dependence of the impedance of the apple tree branch on the signal frequency and branch length was analyzed. The change in the impedance of an apple tree branch during drying was also analyzed. It was shown that, when a branch dries out, the conductivity of the xylem mainly decreases. The developed technique was also applied to determine the development of the vascular system of an apple tree after grafting. It was shown that the processing of the scion and rootstock sections with the help of cold atmospheric plasma and a plasma-treated solution contributes to a better formation of graft unions.

Leaf and canopy stomatal resistance, aerodynamic resistance, and evapotranspiration of irrigated continuous no‐till and disk‐till maize

AbstractThe impact of no‐till (NT) management as compared with conventional tillage practices (e.g., disk till [DT]) on plant stomatal behavior in relation to model estimation of crop evapotranspiration (ETc) and plant physiological functions has not been sufficiently evaluated. This research investigated the effects of NT and DT management on maize (Zea mays L.) physiological parameters and ETc losses. We also tested the methodology to estimate ETc using a one‐step Penman–Monteith (PM) model with measured variable resistance from scaled‐up leaf stomatal resistance (RL) to canopy resistance (RC) with Bowen Ratio Energy Balance System (BREBS)‐measured ETc. Photosynthetic photon flux density (PPFD) explained 76 and 79% of the variability in RL for NT and DT maize, respectively, which varied with growth stage. Disk‐till maize RL was 29, 5, 25, and 4% higher than NT maize RL during the vegetative, tasseling and silking, reproductive, and near‐physiological‐maturity stages, respectively. The seasonal average scaled‐up RC values for NT and DT maize were 102.4 and 128.6 s m–1, respectively. The PM‐estimated ETc correlated strongly with the BREBS‐measured ETc, with the PM model estimates being 8 and 6% within the BREBS measurements on an hourly and daily basis, respectively. To the best of our knowledge, this research is the first to develop the response curves (PPFD vs. RL) for maize for different growth stages under NT and DT. The analyses presented here can provide invaluable data and information for plant physiology research, crop modeling, determining crop response to different management, and environmental drivers.

Cut peony industry: the first 30 years of research and new horizons.

Herbaceous peony is an ancient medicinal and ornamental crop, cultivated in China and Japan for thousands of years. Numerous varieties of different colors are popular garden plants in different continents and countries. In recent decades, peony has gained a new reputation as cut flowers. Only in Europe, in 30 years, trade in cut peony stems has increased 50 fold. Today, more than 25 countries produce cut peony flowers, with primary markets in Europe, Asia and the USA. This short review summarizes the contribution of research in plant physiology to the development of new technologies of peony production and flowering advancement. Despite the popularity of cut peonies, several factors still restrict their production: complicated flowering physiology, challenges in mass propagation, and postharvest handling. Further research of biochemical and molecular mechanisms, as well as breeding of new cultivars will promote the development of the peony industry and facilitate the creation of a Global Peony Chain for the successful marketing of this beautiful flower.

Fourteen Stations of Auxin.

Auxin has always been at the forefront of research in plant physiology and development. Since the earliest contemplations by Julius von Sachs and Charles Darwin, more than a century-long struggle has been waged to understand its function. This largely reflects the failures, successes, and inevitable progress in the entire field of plant signaling and development. Here I present 14 stations on our long and sometimes mystical journey to understand auxin. These highlights were selected to give a flavor of the field and to show the scope and limits of our current knowledge. A special focus is put on features that make auxin unique among phytohormones, such as its dynamic, directional transport network, which integrates external and internal signals, including self-organizing feedback. Accented are persistent mysteries and controversies. The unexpected discoveries related to rapid auxin responses and growth regulation recently disturbed our contentment regarding understanding of the auxin signaling mechanism. These new revelations, along with advances in technology, usher us into a new, exciting era in auxin research.

Evaluation of the Phytochemistry of Aqueous, Ethanolic and Methanolic Extracts of Morus mesozygia Linn. Stapf., Twig

Aim: The aim of this study was to phytochemically analyze the aqueous, ethanolic and methanolic twig extracts of the species Morus mesozygia Linn. Stapf.
 Study Design: This is a cross-sectional study.
 Place and Duration of Study: This study was carried out at the Plant Anatomy and Physiology Research Laboratory, University of Port Harcourt, between July, 2018 and November, 2018.
 Methodology: Morus mesozygia linn twigs were collected and washed with distilled water, air dried for seven days and milled into fine powder. Maceration method was used to extract the powdered twig into a brownish paste using three different solvents; distilled water, ethanol and methanol. The different plant extracts were subjected to qualitative phytochemical screening for alkaloids, flavonoids, saponins, carbohydrates, tannins and anthraquinones. Quantitative phytochemical analysis was done using a Gas chromatography – Mass Spectroscopy machine.
 Results: The results of this study showed that the powdered Morus mesozygia linn twigs contained flavonoids, saponins, carbohydrates, alkaloids, tannins, but not anthraquinones. The methanolic and aqueous twig extracts contained high amounts of alkaloids, flavonoids, saponins, carbohydrates and tannins, while the ethanolic extract also contained high amounts of the aforementioned phytochemicals in the same proportion, but had saponins in moderate amounts. It also showed that the methanolic twig extract had more carbohydrate than the other two extracts. The result of the GC-MS analysis showed that the three extracts contained complex compounds in varying amounts.
 Conclusion: The qualitative and quantitative phytochemical analyses test results of Morus mesozygia Linn Stapf. revealed the presence of the substances like alkaloids, saponins, flavonoids, oils, phenolic compounds, tannins and some complex compounds discovered using GC-MS technique, in their varying concentrations for the three different extracts.

Jagadis Gupta Kapuganti

Jagadis Gupta Kapuganti

HOTS Analysis to Develop E-Supplement Book Based on Plant Physiology Research

Biology learning, especially the topic of plant physiology, requires Higher Order Thinking Skills (HOTS). This ability needs to be improved with HOTS-based teaching materials. The teaching materials, however, have not been developed, especially those in plant physiology topic. Students’ HOTS in biology learning still requires an improvement as HOTS is important for the 21st century. One alternative that can be developed is teaching materials in the form of an E-Supplement Book Based on Plant Physiology Research (ESPPRe). The purpose of this study was to measure students’ HOTS related to the concept of plant physiology as the basis for developing ESPPRe. The method used was descriptive using a survey technique. The instrument used in this study amounted to 10 items distributed using Google form. The results indicated that the scores were categorized as low for all students (40.81) with male students (41.39) and female students (40.74). This suggested that the HOTS score still needs to be improved and it is necessary to develop ESPPRe in further research. The content on the ESPPRe media that must be developed is related to activities to analyze and criticize problems that have been presented in ESPPRe. Next, students are expected to be able to create solutions and ideas related to these problems. The development of various learning media will make students happier in learning. This is because HOTS-based learning implementation will be varied. This study concludes that the HOTS score is still in the low category and the ESPPRe can be developed in subsequent studies. Suggestion from this research is to be able to implement the book to improve students' abilities to solve problems.