Insecticidal and Repellent Activity of Thymus quinquecostatus Celak. Essential Oil and Major Compositions against Three Stored-Product Insects.

Thymus quinquecostatus Celak. of the Lamiaceae family has a long history of dual use of medicine and food with high economic value, and has been proved to have good antioxidative, antimicrobial, and antidiabetic activities. Essential oil (EO) extracted from the aerial part of T. quinquecostatus was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC/MS) and GC. Totally 45 compounds were identified accounting for 98.5 % of the EO. The major constituents of the EO were linalool (52.003 %), borneol (10.911 %) and anethole (5.325 %). Fumigant, contact and repellent activity of T. quinquecostatus essential oil (EO) against Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma Serricorne (Coleoptera: Anobiidae), Liposcelis bostrychophila (Psocoptera: Liposcelididae) were evaluated in this work. T. quinquecostatus EO and three major constituents showed varying degrees of insecticidal and repellent activities to three stored-product insects. Anethole stated the best fumigant and contact activity than others did to all three insect species. EO and compounds showed general repellent activity against three target insects. This work suggests that the EO of T. quinquecostatus has promising potential to be developed into botanical pesticides and repellents controlling pest damage in warehouses and grain stores.

[Biopharmaceutical classification and transport mechanism of 4 alkaloids in Mongolian herbal medicine Sophorae Flavescentis Radix].

In this study, we studied the solubility and permeability of matrine, oxymatrine, sophoridine, and oxysophocarpine, four alkaloids in the Mongolian herbal medicine Sophorae Flavescentis Radix, and evaluated the absorption mechanism with the Caco-2 cell model, so as to provide a basis for the new drug development and efficacy evaluation of Sophorae Flavescentis Radix. The results showed that all the four alkaloids had high solubility and high permeability and can be well absorbed, belonging to the class-I drugs of Biopharmaceutical Classification System(BCS). The absorption(AP→BL) and excretion(BL→AP) of matrine and oxymatrine were not affected by the concentration while the absorption depended on P-gp protein. The absorption(AP→BL) and excretion(BL→AP) of sophoridine and oxysophocarpine were positively related to the concentration and time, and the absorption process was independent from P-gp protein. The results provide scientific reference and an experimental basis for the development of Mongolian medical prescriptions containing Sophorae Flavescentis Radix.

Efficacy of Compounds Isolated from the Essential Oil of Artemisia lavandulaefolia in Control of the Cigarette Beetle, Lasioderma serricorne.

To develop natural product resources to control cigarette beetles (Lasioderma serricorne), the essential oil from Artemisia lavandulaefolia (Compositae) was investigated. Oil was extracted by hydrodistillation of the above-ground portion of A. lavandulaefolia and analyzed using gas chromatography-mass spectrometer (GC-MS). Extracted essential oil and three compounds isolated from the oil were then evaluated in laboratory assays to determine the fumigant, contact, and repellent efficacy against the stored-products' pest, L. serricorne. The bioactive constituents from the oil extracts were identified as chamazulene (40.4%), 1,8-cineole (16.0%), and ß-caryophyllene (11.5%). In the insecticidal activity assay, the adults of L. serricorne were susceptible to fumigant action of the essential oil and 1,8-cineole, with LC50 values of 31.81 and 5.18 mg/L air. The essential oil, 1,8-cineole, chamazulene, and ß-caryophyllene exhibited contact toxicity with LD50 values of 13.51, 15.58, 15.18 and 35.52 µg/adult, respectively. During the repellency test, the essential oil and chamazulene had repellency approximating the positive control. The results indicated that chamazulene was abundant in A. lavandulaefolia essential oil and was toxic to cigarette beetles.

A meta-analysis of leaf nitrogen distribution within plant canopies.

BACKGROUND AND AIMS: Leaf nitrogen distribution in the plant canopy is an important determinant for canopy photosynthesis. Although the gradient of leaf nitrogen is formed along light gradients in the canopy, its quantitative variations among species and environmental responses remain unknown. Here, we conducted a global meta-analysis of leaf nitrogen distribution in plant canopies. METHODS: We collected data on the nitrogen distribution and environmental variables from 393 plant canopies (100, 241 and 52 canopies for wheat, other herbaceous and woody species, respectively). KEY RESULTS: The trends were clearly different between wheat and other species; the photosynthetic nitrogen distribution coefficient (Kb) was mainly determined by leaf area index (LAI) in wheat, whereas it was correlated with the light extinction coefficient (KL) and LAI in other species. Some other variables were also found to influence Kb We present the best equations for Kb as a function of environmental variables and canopy characteristics. As a more simple function, Kb = 0·5KL can be used for canopies of species other than wheat. Sensitivity analyses using a terrestrial carbon flux model showed that gross primary production tended to be more sensitive to the Kb value especially when nitrogen content of the uppermost leaf was fixed. CONCLUSION: Our results reveal that nitrogen distribution is mainly driven by the vertical light gradient but other factors such as LAI also have significant effects. Our equations contribute to an improvement in the projection of plant productivity and cycling of carbon and nitrogen in terrestrial ecosystems.

[Study on extraction process of coumarin in a Mongolian drug Chagan-sorlo (Radix Glehniae)].

The present paper discusses ultrasonic extraction method aided extraction of coumarin from a Mongolian drug, Chagan-sorlo (Radix Glehniae), aiming to study out how much coumarin contained in Chagan-sorlo, and to provide the scientific basis and production guidance for extracting coumarin from Chagan-sorlo. Under different conditions the coumarin in Chagan-sorlo was extracted by ultrasonic, measured and analyzed, and then HPLC was used to carry out the measurement. Result showed that with solvent volume fraction of 70%, extraction time of 20 min, ultrasonic power of 175 W, temperature of 25 degrees C, solid-liquid ratio of 1 : 20, and 80-100 mesh extraction, the coumarin extraction reaches the highest yield.

Ethnobotanical study of Zhuang medicinal herbs of Ardisia: variety systematization, traditional uses, phytochemistry, pharmacology, clinical application, and toxicity.

OBJECTIVES: This study aimed to systematize the Zhuang medicinal herbs of Ardisia (ZMHA) in China, to clarify the traditional use in Zhuang medicine and the dynamics of international research on phytochemistry, pharmacology, clinical application, and toxicity. KEY FINDINGS: There are 25 species of ZMHA, approximately 938 compounds from the different part, including triterpenoids, phenolics, volatile oils, etc. Pharmacological activity studies have also shown that this genus has anti-tumour, anti-inflammatory, anti-oxidant, anti-bacterial, anti-microbial, etc., and significant effects on respiratory, digestive, urinary, and musculoskeletal system diseases without toxic side effects. SUMMARY: The Ardisia has a medicinal history of nearly a thousand years, mainly for treating diseases of the injuries, musculoskeletal, and symptomatic system in Zhuang medicine. Some plants, such as A. crenata, A. gigantifolia, and A. japonica, are also commonly used in folk Zhuang medicine formulas, to treat musculoskeletal, injury, respiratory, and urinate systems disease. These diseases are related to inflammation. These could provide a new direction for future new drug development research. Therefore, species identification and resource investigation should be strengthened, and conducted in vitro mechanism, in vivo pharmacology, clinical efficacy, and toxicology studies and establish a perfect quality standard system.

Species identification of biological ingredients in herbal product, Gurigumu-7, based on DNA barcoding and shotgun metagenomics.

Accurate identification the species composition in mixtures poses a significant challenge, especially in processed mixtures comprising multiple species, such as those found in food and pharmaceuticals. Therefore, we have attempted to utilize shotgun metabarcoding technology to tackle this issue. In this study, the method was initially established using two mock samples of the Mongolian compound preparation Gurigumu-7 (G-7), which was then applied to three pharmaceutical products and 12 hospital-made preparations. A total of 119.72 Gb of raw data sets were obtained through shotgun metagenomic sequencing. By combining ITS2, matK, and rbcL, all the labeled bio-ingredients specified in the G-7 prescription can be detected, although some species may not be detectable in all samples. The prevalent substitution of Akebia quinata can be found in all the pharmaceutical and hospital samples, except for YN02 and YN12. The toxic alternative to Akebia quinata, Aristolochia manshuriensis, was exclusively identified in the YN02 sample. To further confirm this result, we validated it in YN02 using HPLC and real-time PCR with TaqMan probes. The results showed that aristolochic acid A (AAA) was detected in YN02 using HPLC, and the ITS2 sequence of Aristolochia manshuriensis has been validated in YN02 through qPCR and the use of a TaqMan probe. This study confirms that shotgun metabarcoding can effectively identify the biological components in Mongolian medicine compound preparation G-7. It also demonstrates the method's potential to be utilized as a general identification technique for mixtures containing a variety of plants.

Metabolomics analysis reveals the effects of Salvia Miltiorrhiza Bunge extract on ameliorating acute myocardial ischemia in rats induced by isoproterenol.

Salvia miltiorrhiza Bunge (SM) is a widespread herbal therapy for myocardial ischemia (MI). Nevertheless, the therapeutic signaling networks of SM extract on MI is yet unknown. Emerging evidences suggested that alterations in cardiac metabolite influences host metabolism and accelerates MI progression. Herein, we employed an isoproterenol (ISO)-induced acute myocardial ischemia (AMI) rat model to confirm the pharmacological effects of SM extract (0.8, 0.9, 1.8 g/kg/day) via assessment of the histopathological alterations that occur within the heart tissue and associated cytokines; we also examined the underlying SM extract-mediated signaling networks using untargeted metabolomics. The results indicated that 25 compounds with a relative content higher than 1 % in SM aqueous extract were identified using LC-MS/MS analysis, which included salvianolic acid B, lithospermic acid, salvianolic acid A, and caffeic acid as main components. An in vivo experiment showed that pretreatment with SM extract attenuated ISO-induced myocardial injury, shown as decreased myocardial ischemic size, transformed electrocardiographic, histopathological, and serum biochemical aberrations, reduced levels of proinflammatory cytokines, inhibited oxidative stress (OS), and reversed the trepidations of the cardiac tissue metabolic profiles. Metabolomics analysis shows that the levels of 24 differential metabolites (DMs) approached the same value as controls after SM extract therapy, which were primarily involved in histidine; alanine, aspartate, and glutamate; glycerophospholipid; and glycine, serine, and threonine metabolisms through metabolic pathway analysis. Correlation analysis demonstrated that the levels of modulatory effects of SM extract on the inflammation and OS were related to alterations in endogenous metabolites. Overall, SM extract demonstrated significant cardioprotective effects in an ISO-induced AMI rat model, alleviating myocardial injury, inflammation and oxidative stress, with metabolomics analysis indicating potential therapeutic pathways for myocardial ischemia.

[Impacts of climate warming on nine element contents in Mongolian drug Agi using ICP-AES].

Global warming has become a fact of life, and the night temperature increase higher than during the day. In the present research, to explore the effects of climate warming on element contents of plants, ICP-AES was used for the direct determination of nine kinds of element contents of reproductive branches and vegetative branches of the Mongolian drug Agi, which grew in the day, night and diurnal warming field. The results of the study show that the responses of reproductive branches and vegetative branches to day, night and diurnal warming were not significant different, but the negative response was greater than the positive response. The effects of day warming on the element contents were not significant, but night warming lower the contents of Al, Fe and Mn significantly. There was interaction between day warming and night warming.

Plant nitrogen retention in alpine grasslands of the Tibetan Plateau under multi-level nitrogen addition.

Nitrogen (N) deposition might alleviate degradation of alpine grassland caused by N limitation on the Tibetan Plateau (TP). To determine such limitation and quantify the N-induced N retention in plant, a six-year fertilization experiment with six levels of N addition rates (0, 1, 2, 4, 8 and 16 g N m-2 yr-1) was conducted in the Namco alpine steppe and additional 89 experiments with multi-level N addition were also synthesized worldwide among which 27 sites were on the TP. In general, N addition promoted N retention in plants, and this increasing trend diminished at the critical N rate (Ncr). The maximum N retention capacity (MNRC) of plants at Ncr was strongly correlated with initial aboveground net primary productivity with a slope of 0.02, and the MNRC of grasslands globally ranged from 0.35 to 42.59 g N m-2 yr-1, approximately account for 39% of Ncr. Tibetan alpine grassland had a low average MNRC (2.24 g N m-2 yr-1) with distinct regional characteristic, which was much lower in the western TP (0.80 g N m-2 yr-1) than the eastern TP (4.10 g N m-2 yr-1). Our results inferred 0.33-1.21 Tg N yr-1 (0.22-0.79 g N m-2 yr-1) can be retained and 5.65-20.11 Tg C yr-1 (3.67-13.06 g C m-2 yr-1) can be gained by Tibetan alpine grasslands under current N deposition level. With the aggravation of N deposition, the alpine steppe ecosystem might continuously absorb N and C until N deposition reaches Ncr.

Astragaloside IV against Alzheimer's disease via microglia-mediated neuroinflammation using network pharmacology and experimental validation.

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases in the world. The effective therapeutic methods and drugs are still not clear. Astragaloside IV (AS-IV), a triterpenoid saponin isolated from the root of Huangqi, has a beneficial effect in the treatment of AD. However, whether AS-IV alters microglia in the inflammation of AD is still ambiguous. In our study, 99 common targets were collected between AS-IV and AD. BCL2 apoptosis regulator (Bcl-2), pro-apoptotic BCL-2 protein BAX, epidermal growth factor receptor (EGFR), and receptor tyrosine phosphatase type C (PTPRC) were screened for inflammation and microglia in the above targets by network pharmacology. Interleukin-1ß (IL-1ß) and EGFR both interact with signal transducer and activator of transcription 3 (STAT3) by a protein interaction network, and IL-1ß had a higher affinity for AS-IV based on molecular docking. Enrichment revealed targets involved in the regulation of neuronal cell bodies, growth factor receptor binding, EGFR tyrosine kinase inhibitor resistance., etc. Besides, AS-IV alleviated the reduced cell proliferation in amyloid-beta (Aß)-treated microglial BV2 cells. AS-IV affected BV2 cell morphological changes and decreased cluster of differentiation 11b (CD11b) gene, IL-1ß, and EGFR mRNA levels increment during lipopolysaccharide (LPS) injury in BV2 cell activation. Therefore, AS-IV may regulate microglial activation and inflammation via EGFR-dependent pathways in AD. EGFR and IL-1ß are vital targets that may relate to each other to coregulate downstream molecular functions in the cure of AD. Our study provides a candidate drug and disease target for the treatment of neurodegenerative diseases in the clinic.

Ardisia gigantifolia stapf (Primulaceae): A review of ethnobotany, phytochemistry, pharmacology, clinical application, and toxicity.

ETHNOPHARMACOLOGICAL RELEVANCE: Ardisia gigantifolia Stapf, known as Zou-ma-tai (in Chinese), is a traditional folk medicine, which was commonly used by Dong, Jing, Li, Maonan, Miao, Mulam, Yao, and Zhuang people. The main use of A. gigantifolia is the treatment of rheumatoid arthritis, gouty arthritis, fractures, osteoproliferation, traumatic injuries, gynecological, and neurological diseases. Current studies have shown that the plant has various bioactive components, especially gigantifolinol, which has anti-tumor, anti-inflammatory, anti-tuberculosis, and neuroprotective activities. However, to date, few reviews have been made to summarize A. gigantifolia's related studies. AIMS OF THE REVIEW: This review aimed to summarize the traditional use, phytochemistry, pharmacology, clinical applications, and toxicity of A. gigantifolia, which expect to provide theoretical support for future utilization and highlight the further investigation of this vital plant. MATERIALS AND METHODS: The information related to A. gigantifolia were collated by surveying the traditional medicine books, ethnomedicinal publications, and searching academic resource databases including Web of Science, SciFinder, Springer Link, Pub Med, Science Direct, CNKI, and CQVIP database. RESULTS: A. gigantifolia has been used as a traditional folk medicine for more than 400 years in China. Different parts of the plant, including the aerial part, root, rhizome, and leaf, are mainly used as herbal medicine to treat rheumatoid arthritis, traumatic injuries, gynecological, etc. Currently, 165 compounds have been identified from the plant, including triterpenes, phenolics, coumarins, quinones, volatile oil, and sterols, 137 of which were identified from the rhizome parts. Pharmacological research showed that A. gigantifolia has various bioactivities, such as anti-tumor, anti-inflammatory, anti-oxidant, anti-thrombus, anti-tuberculosis, cough expectorant, and neuroprotective activities. Clinical studies have shown that the plant has no toxic side effects. In vivo administration at the maximum dose was not lethal, indicating the plant's safety. CONCLUSION: To date, most bioactive compounds are identified from the rhizomes of A. gigantifolia, which pharmacological activity and clinical observational studies have validated the plant's traditional use as a treatment for rheumatoid arthritis. It would be helpful to verify the mechanism of some components in vivo, such as gigantifolinol. Moreover, the plant's triterpenoid saponins demonstrated valid anti-tumor effects, especially the AG4 and AG36 compounds, which were shown to have anti-breast cancer effects both in vitro and in vivo. Further research on these components, including molecular mechanisms and in vivo metabolic regulation, needs to be confirmed.

Bioactivities of thymol and p-cymene from the essential oil of Adenosma buchneroides against three stored-product insects.

The adverse effects of relying solely on synthetic pesticides have become increasingly evident, leading many countries to explore alternatives sourced from plant-based green economies. Essential oil (EO) from stems and leaves of Adenosma buchneroides Bonati (A. buchneroides) was distilled by using hydrodistillation and subjected to gas chromatography-mass spectrometry (GC-MS) for component identification. Subsequently, EO as well as its main constituents (thymol and p-cymene) were tested for their insecticidal activity against the red flour beetle (Tribolium castaneum), the cigarette beetle (Lasioderma serricorne), and the booklouse (Liposcelis bostrychophila). The joint action of thymol and p-cymene produced an additive or synergistic effect. A. buchneroides essential oil (BHO) and the fixed ratio of the main compounds, thymol, and p-cymene both showed significant toxic activity against the target pests. This toxic effect is not simply the sum of individual effects, as it is influenced by various factors such as insect species and mode of action. These findings imply that the BHO and its phytoconstituents possess great potential to develop plant-derived biopesticides that will be safe for humans and the environment.

Mongolian medicine: History, development and existing problems.

Mongolian medicine (MM) is an important part of Mongolian culture. Exploration of MM can play a crucial role in the prevention and treatment of various diseases and can help provide better health care globally. In this article, we gave a brief introduction to the origin and development of MM, the theoretical system of MM, the principles of Mongolian materia medica formula, the modern research on Mongolian materia medica and the quality control of Mongolian materia medica. The present situation and outlook of MM were also discussed.

Nitrogen deposition accelerates greenhouse gas emissions at an alpine steppe site on the Tibetan Plateau.

The increase in atmospheric N deposition can alter the exchange of greenhouse gas (GHG) between the biosphere and atmosphere. The effect of N deposition on GHG is poorly understood in alpine steppe. Therefore, we conducted a 4-year experiment with multilevel N addition of 0, 10, 20, 40, 80, 160 kg N ha-1 using the static chamber and gas chromatography method to quantify responses of GHG fluxes and characterize the relationship between GHG fluxes and N addition rate in Namco located in the alpine steppe in the central Tibetan Plateau (TP). The mean CO2 efflux, CH4 uptake, N2O emission during growing seasons across four years were 33.59 ± 16.41 mg C m-2 h-1, -56.42 ± 29.20 µg C m-2 h-1, 0.67 ± 4.40 µg N m-2 h-1 respectively. CO2 efflux increased 1.55-22.6%, CH4 uptake decreased 5.96-20.1%, N2O emission increased 37.3-133.5% with N addition. We also observed a critical threshold of 40 kg N ha-1 a-1 of N addition above which the increase rate of N2O emission would diminish. Our current results implied that under the background of future N deposition, N induced C sequestration might be offset by GHG balance causing a heating effect to the climate.

Gypenoside LI arrests the cell cycle of breast cancer in G0/G1 phase by down-regulating E2F1.

ETHNOPHARMACOLOGICAL RELEVANCE: Gynostemma pentaphyllum (Thunb.) Makino, a traditional medicine in China, has been widely used for the treatment of various diseases. Gypenoside LI (Gyp LI) is a major constituent from steamed G. pentaphyllum. Previous studies have shown that gypnenoside LI possess inhibitory effect on the growth of many cancer cells. However, its pharmacological effect in breast cancer and the mechanism have not been reported yet. AIM OF THE STUDY: To investigate the anti-breast cancer activity of gypenoside LI and underlying mechanisms of gypenoside LI in MDA-MB-231 and MCF-7 cells. MATERIAL/METHODS: The cytotoxicity of gypenoside LI was determined by MTT, colony-formation and three-dimensional spheroid assay. The migration, cell apoptosis and the cell cycle were investigated through cell morphology observation, flow cytometry analysis and key proteins detection. The anticancer mechanisms of gypenoside LI were detected by RNA sequencing (RNA-seq) and Gene Set Enrichment Analysis (GSEA) transcriptome analysis. RESULTS: Gypenoside LI inhibited cell proliferation, migration, induced cell apoptosis and cell cycle arrest. Gypenoside LI arrested cell cycle at G0/G1 phase by regulating E2F1. It also inhibited tumor proliferation by regulating the expression of ERCC6L. Interestingly, we found that E2F1 siRNA also down-regulated the expression of ERCC6L. Gypenoside LI showed potential anti-breast cancer cells activity, especially on triple-negative breast cancer cells. CONCLUSIONS: These data indicate that gypenoside LI could inhibit human breast cancer cells through inhibiting proliferation and migration, inducing apoptosis, arresting cell cycle at G0/G1 phase by regulating E2F1. It could be used as potential multi-target chemopreventive agents for cancer.

Folk nomenclature of plants in Cistanche deserticola-associated community in South Gobi, Mongolia.

Cistanche deserticola is an important medicinal plant in Mongolia. Despite its significant role in local healing systems, little traditional knowledge had been reported. The present study investigated folk names of C. deserticola and other species of the same community in Umnugobi Province, South Gobi region of Mongolia, based on ethnobotanical approaches. The high correspondence between folk names and scientific names of plant species occurring in Cistanche-associated community shows the scientific meaning of folk nomenclature and classification in Mongolia. The Mongolian and folk names of plants were formed on the basis of observations and understanding of wild plants including their morphology, phenology and traditional uses as well. Results from this study will support the conservation of C. deserticola itself, a rare and endangered plant species listed in the Monglian Red Data Book. Our documentation of folk nomenclature based on 96 plant species in the Cistanche community, as a part of traditional knowledge associated with biodiversity, will be very helpful for making strategy of plant biodiversity conservation in Mongolia.

[Temperature dependence of parameters of plant photosynthesis models: a review].

This paper reviewed the progress on the temperature response models of plant photosynthesis. Mechanisms involved in changes in the photosynthesis-temperature curve were discussed based on four parameters, intercellular CO2 concentration, activation energy of the maximum rate of RuBP (ribulose-1,5-bisphosphate) carboxylation (V (c max)), activation energy of the rate of RuBP regeneration (J(max)), and the ratio of J(max) to V(c max) All species increased the activation energy of V(c max) with increasing growth temperature, while other parameters changed but differed among species, suggesting the activation energy of V(c max) might be the most important parameter for the temperature response of plant photosynthesis. In addition, research problems and prospects were proposed. It's necessary to combine the photosynthesis models at foliage and community levels, and to investigate the mechanism of plants in response to global change from aspects of leaf area, solar radiation, canopy structure, canopy microclimate and photosynthetic capacity. It would benefit the understanding and quantitative assessment of plant growth, carbon balance of communities and primary productivity of ecosystems.

Temperature acclimation of photosynthesis: mechanisms involved in the changes in temperature dependence of photosynthetic rate.

Growth temperature alters temperature dependence of the photosynthetic rate (temperature acclimation). In many species, the optimal temperature that maximizes the photosynthetic rate increases with increasing growth temperature. In this minireview, mechanisms involved in changes in the photosynthesis-temperature curve are discussed. Based on the biochemical model of photosynthesis, change in the photosynthesis-temperature curve is attributable to four factors: intercellular CO2 concentration, activation energy of the maximum rate of RuBP (ribulose-1,5-bisphosphate) carboxylation (Vc max), activation energy of the rate of RuBP regeneration (Jmax), and the ratio of Jmax to Vc max. In the survey, every species increased the activation energy of Vc max with increasing growth temperature. Other factors changed with growth temperature, but their responses were different among species. Among these factors, activation energy of Vc max may be the most important for the shift of optimal temperature of photosynthesis at ambient CO2 concentrations. Physiological and biochemical causes for the change in these parameters are discussed.

Seasonal changes in temperature dependence of photosynthetic rate in rice under a free-air CO(2) enrichment.

BACKGROUND AND AIMS: Influences of rising global CO(2) concentration and temperature on plant growth and ecosystem function have become major concerns, but how photosynthesis changes with CO(2) and temperature in the field is poorly understood. Therefore, studies were made of the effect of elevated CO(2) on temperature dependence of photosynthetic rates in rice (Oryza sativa) grown in a paddy field, in relation to seasons in two years. METHODS: Photosynthetic rates were determined monthly for rice grown under free-air CO(2) enrichment (FACE) compared to the normal atmosphere (570 vs 370 micromol mol(-1)). Temperature dependence of the maximum rate of RuBP (ribulose-1,5-bisphosphate) carboxylation (V(cmax)) and the maximum rate of electron transport (J(max)) were analysed with the Arrhenius equation. The photosynthesis-temperature response was reconstructed to determine the optimal temperature (T(opt)) that maximizes the photosynthetic rate. KEY RESULTS AND CONCLUSIONS: There was both an increase in the absolute value of the light-saturated photosynthetic rate at growth CO(2) (P(growth)) and an increase in T(opt) for P(growth) caused by elevated CO(2) in FACE conditions. Seasonal decrease in P(growth) was associated with a decrease in nitrogen content per unit leaf area (N(area)) and thus in the maximum rate of electron transport (J(max)) and the maximum rate of RuBP carboxylation (V(cmax)). At ambient CO(2), T(opt) increased with increasing growth temperature due mainly to increasing activation energy of V(cmax). At elevated CO(2), T(opt) did not show a clear seasonal trend. Temperature dependence of photosynthesis was changed by seasonal climate and plant nitrogen status, which differed between ambient and elevated CO(2).