Guard cell and subsidiary cell sizes are key determinants for stomatal kinetics and drought adaptation in cereal crops

Climate change-induced drought is a major threat to agriculture. C4 crops have a higher water use efficiency (WUE) and better adaptability to drought than C3 crops due to their smaller stomatal morphology and faster response. However, our understanding of stomatal behaviours in both C3 and C4 Poaceae crops is limited by knowledge gaps in physical traits of guard cell (GC) and subsidiary cell (SC). We employed infrared gas exchange analysis and a stomatal assay to explore the relationship between GC/SC sizes and stomatal kinetics across diverse drought conditions in two C3 (wheat and barley) and three C4 (maize, sorghum and foxtail millet) upland Poaceae crops. Through statistical analyses, we proposed a GCSC-τ model to demonstrate how morphological differences affect stomatal kinetics in C4 Poaceae crops. Our findings reveal that morphological variations specifically correlate with stomatal kinetics in C4 Poaceae crops, but not in C3 ones. Subsequent modelling and experimental validation provide further evidence that GC/SC sizes significantly impact stomatal kinetics, which affects stomatal responses to different drought conditions and thereby WUE in C4 Poaceae crops. These findings emphasize the crucial advantage of GC/SC morphological characteristics and stomatal kinetics for the drought adaptability of C4 Poaceae crops, highlighting their potential as future climate-resilient crops.

Stomatal Responses of Two Drought-Tolerant Barley Varieties with Different ROS Regulation Strategies under Drought Conditions

Drought stress is a major obstacle to agricultural production. Stomata are central to efforts to improve photosynthesis and water use. They are targets for manipulation to improve both processes and the balance between them. An in-depth understanding of stomatal behavior and kinetics is important for improving photosynthesis and the WUE of crops. In this study, a drought stress pot experiment was performed, and a transcriptome analysis of the leaves of three contrasting, cultivated barley genotypes Lumley (Lum, drought-tolerant), Golden Promise (GP, drought-sensitive), and Tadmor (Tad, drought-tolerant), generated by high-throughput sequencing, were compared. Lum exhibited a different WUE at the leaf and whole-plant levels and had greater CO₂ assimilation, with a higher g_s under drought stress. Interestingly, Lum showed a slower stomatal closure in response to a light-dark transition and significant differences compared to Tad in stomatal response to the exogenous application of ABA, H₂O₂, and CaCl₂. A transcriptome analysis revealed that 24 ROS-related genes were indeed involved in drought response regulation, and impaired ABA-induced ROS accumulation in Lum was identified using ROS and antioxidant capacity measurements. We conclude that different stomatal ROS responses affect stomatal closure in barley, demonstrating different drought regulation strategies. These results provide valuable insight into the physiological and molecular basis of stomatal behavior and drought tolerance in barley.

Quantitative System Modeling Bridges the Gap between Macro- and Microscopic Stomatal Model

An understanding of stomatal function is vital for the carbon and water cycle in nature. In the past decades, various stomatal models with different functions have been established to investigate and predict stomatal behavior and its association with plants' responses to the changing climate, but with limited biological information provided. On the other hand, many stomatal models at the molecular level focus on simulating and predicting molecular practices and ignore the dynamic quantitative information. As a result, stomatal models are often divided between the microscopic and macroscopic scales. Quantitative systems analysis offers an effective in silico approach to explore the link between microscopic gene function and macroscopic physiological traits. As a first step, a systems model, OnGuard, is developed for the investigation of guard cell ion homeostasis and its relevance to the dynamic stomatal movements. The system model has already yielded a series of important predictions to guide molecular physiological studies in stomata. It also exhibits great potential in breeding practice, which represents a key step toward "Breeding by design" of improving plant carbon-water use efficiency. Here, the development of stomatal models is reviewed, and the future perspectives on stomatal modeling for agricultural and ecological applications are discussed.

OsFTIP7 determines metallic oxide nanoparticles response and tolerance by regulating auxin biosynthesis in rice

The widely application of metallic oxide nanoparticles (NPs) has led to an increase in their accumulation in farmland. Previous studies have found that the metallic oxide NPs have negative effect on plants development and growth. Nonetheless, the underlying mechanism of response to metallic oxide NPs in rice remains elusive. In this study, we show that rice FT-INTERACTING PROTEIN 7 (OsFTIP7) plays an essential role in NPs of CuO and ZnO-mediated physiological and biochemical changes in rice. Loss of function of OsFTIP7 reduced the toxicity of the NPs of CuO and ZnO to the seedlings by accumulating more biomass and chlorophyll contents. Furthermore, after high exposure to metallic oxide NPs, more indole-3-acetic acid (IAA) were determined in Osftip7 with higher expression of auxin biosynthetic genes than the control seedlings. What's more, IAA-treated seedlings displayed the similar phenotype as Osftip7 under high concentrations of NPs of CuO and ZnO. Taken together, the results substantiate that OsFTIP7 is involved in metallic oxide nanoparticle-mediated physiological and biochemical changes by negatively regulating auxin biosynthesis in rice.

Optimized Protocol for OnGuard2 Software in Studying Guard Cell Membrane Transport and Stomatal Physiology

Stomata are key innovation in plants that drives the global carbon and water cycle. In the past few decades, many stomatal models have been developed for studying gas exchange, photosynthesis, and transpirational characteristics of plants, but they provide limited information on stomatal mechanisms at the molecular and cellular levels. Quantitative mathematical modeling offers an effective in silico approach to explore the link between microscopic transporter functioning and the macroscopic stomatal characteristics. As a first step, a dynamic system model based on the guard cell membrane transport system was developed and encoded in the OnGuard software. This software has already generated a wealth of testable predictions and outcomes sufficient to guide phenotypic and mutational studies. It has a user-friendly interface, which can be easily accessed by researchers to manipulate the key elements and parameters in the system for guard cell simulation in plants. To promote the adoption of this OnGuard application, here we outline a standard protocol that will enable users with experience in basic plant physiology, cell biology, and membrane transport to advance quickly in learning to use it.

Alteration of Crop Yield and Quality of Wheat upon Exposure to Silver Nanoparticles in a Life Cycle Study

As a result of the rapid development of nanotechnology, metal-based nanoparticles (NPs) are inadvertently released into the environment and may pose a potential threat to the ecosystem. However, information for food quality and safety in NP-treated crops is limited. In the present study, wheat ( Triticum aestivum L.) was grown in different concentrations of Ag-NP-amended soil (20, 200, and 2000 mg kg^-1) for 4 months. At harvest, physiological parameters, Ag and micronutrient (Fe, Cu, and Zn) contents, and amino acid and total protein contents were measured. Results showed that, with increasing the exposure doses, Ag NPs exhibited severe phytotoxicity, including lower biomass, shorter plant height, and lower grain weight. Ag accumulation in roots was significantly higher than that in shoots and grains. Decreases in the content of micronutrients (Fe, Cu, and Zn) in Ag-NP-treated grains suggested low crop quality. The results of amino acid and protein contents in Ag-NP-treated wheat grains indicated that Ag NPs indeed altered the nutrient contents in the edible portion. In the amino acid profile, the presence of Ag NPs significantly decreased the contents of arginine and histidine by 13.0 and 11.8%, respectively. In summary, the effects of metal-based NPs on the edible portion of crops should be taken into account in the evaluation of nanotoxicity to terrestrial plants. Moreover, investigation of the potential impacts of NP-caused nutrient alterations on human health could further our understandings on NP-induced phytotoxicity.

Phytotoxicity of CeO2 nanoparticles on radish plant (Raphanus sativus)

Cerium oxide nanoparticles (CeO₂ NPs) have been considered as one type of emerging contaminants that pose great potential risks to the environment and human health. The effect of CeO₂ NPs on plant-edible parts and health evaluation remains is necessary and urgently to be developed. In this study, we cultivated radish in Sigma CeO₂ NP (<25 nm)-amended soils across a series of concentration treatments, i.e., 0 mg/kg as the control and 10, 50, and 100 mg/kg CeO₂ NPs. The results showed that CeO₂ NPs accelerated the fresh biomass accumulation of radish plant; especially in the treatment of 50 mg/kg CeO₂ NPs, root expansion was increased by 2.2 times as much as the control. In addition, the relative chlorophyll content enhanced by 12.5, 12.9, and 12.2% was compared to control on 40 cultivation days. CeO₂ NPs were mainly absorbed by the root and improved the activity of antioxidant enzyme system to scavenge the damage of free radicals in radish root and leaf. In addition, this study also indicated that the nanoparticles might enter the food chain through the soil into the edible part of the plant, which will be a potential threat to human health.

Iron Oxide Nanoparticles as a Potential Iron Fertilizer for Peanut (Arachis hypogaea)

Nanomaterials are used in practically every aspect of modern life, including agriculture. The aim of this study was to evaluate the effectiveness of iron oxide nanoparticles (Fe2O3 NPs) as a fertilizer to replace traditional Fe fertilizers, which have various shortcomings. The effects of the Fe2O3 NPs and a chelated-Fe fertilizer (ethylenediaminetetraacetic acid-Fe; EDTA-Fe) fertilizer on the growth and development of peanut (Arachis hypogaea), a crop that is very sensitive to Fe deficiency, were studied in a pot experiment. The results showed that Fe2O3 NPs increased root length, plant height, biomass, and SPAD values of peanut plants. The Fe2O3 NPs promoted the growth of peanut by regulating phytohormone contents and antioxidant enzyme activity. The Fe contents in peanut plants with Fe2O3 NPs and EDTA-Fe treatments were higher than the control group. We used energy dispersive X-ray spectroscopy (EDS) to quantitatively analyze Fe in the soil. Peanut is usually cultivated in sandy soil, which is readily leached of fertilizers. However, the Fe2O3 NPs adsorbed onto sandy soil and improved the availability of Fe to the plants. Together, these results show that Fe2O3 NPs can replace traditional Fe fertilizers in the cultivation of peanut plants. To the best of our knowledge, this is the first research on the Fe2O3 NPs as the iron fertilizer.

Molecular cloning and characterization of chemokine-like factor 1 (CKLF1), a novel human cytokine with unique structure and potential chemotactic activity

Cytokines are small proteins that have an essential role in the immune and inflammatory responses. The repertoire of cytokines is becoming diverse and expanding. Here we report the identification and characterization of a novel cytokine designated as chemokine-like factor 1 (CKLF1). The full-length cDNA of CKLF1 is 530 bp long and a single open reading frame encoding 99 amino acid residues. CKLF1 bears no significant similarity to any other known cytokine in its amino acid sequence. Expression of CKLF1 can be partly inhibited by interleukin 10 in PHA-stimulated U937 cells. Recombinant CKLF1 is a potent chemoattractant for neutrophils, monocytes and lymphocytes; moreover, it can stimulate the proliferation of murine skeletal muscle cells. These results suggest that CKLF1 might have important roles in inflammation and in the regeneration of skeletal muscle.

[Stimulatory effect of chemokine-like factor 1 (CKLF1) on the growth of bone marrow cells]

OBJECTIVE

To investigate the activity of CKLF1 on the proliferation and differentiation of bone marrow cells.

METHODS

Human low density bone marrow cells and mouse bone marrow cells were plated in 96-well microplate and supernatants from transfected COS-7 cell culture were added. The cell proliferation was assayed by MTT method after 5 days incubation. The enhancing effect of CKLF1 on the colony formation of human hematopoietic progenitor cells was identified in semi-solid culture.

RESULTS

CKLF1 has obvious enhancing effect on both human and mouse bone marrow cells, it can stimulate the colony formation of human hematopoietic stem cells and has synergistic action with GM-CSF.

CONCLUSION

CKLF1 can promote the proliferation and differentiation of bone marrow cells.

[Expression of P-gp, MRP and p53 and their clinical significance in human lung cancer tissues]

BACKGROUND

To investigate the clinical roles of P-gp, MRP and p53 expression and their relationship with one another in primary lung cancer.

METHODS

P-gp, MRP and p53 proteins were measured in 31 paraffin-embedded lung cancer tissues and corresponding normal lung tissues by immunohistochemistry(IHC). In addition, flow cytometric analysis of P-gp and p53 was performed in 29 of 31 frozen lung cancer specimens in order to compare the results of the two methods.

RESULTS

By IHC, positive rates of P-gp, MRP and p53 were 61.3%, 54.8%, 71.0% respectively in 31 lung cancer cases and there was no expression in all normal lung tissues. P-gp and MRP expressed only in NSCLC. The poorer the cancer cell differentiated, the lower the positive rate of P-gp expression was (P<0.05). Squamous cell carcinomas showed much higher positive rate of p53 than adenocarcinomas did (P<0.01). As compared with the non-smokers, staining for p53 was overwhelmingly positive in the smokers (P<0.05). Neither P-gp nor MRP had significant correlation with p53, however, coexpression of P-gp and MRP had a distinct statistic significance (P<0.01). By flow cytometry (FCM), the expression rates of P-gp and p53 were 65.5% and 79.3% in 29 lung cancer cases. The coincident rates of P-gp and p53 by IHC and FCM were 62.1%, 75.9% respectively.

CONCLUSIONS

P-gp and MRP overexpression may be involved in the process of lung cancer in co-ordination. Neither P-gp overexpression nor MRP overexpression has significant correlation with p53 alteration.

[Expressions of p21 and CD44v in human lung cancer and their significance.]

BACKGROUND

To investigate the clinical role of p21 and CD44v in primary lung cancer and their relationship with each other.

METHODS

p21 and CD44v expression in 29 frozen lung cancer and 10 corresponding non-cancer tissues were measured by flow cytometry (FCM) .

RESULTS

In lung cancer , the expression rates of p21 and CD44v were 75. 9 % and 51. 7 % respectively. The two proteins showed much higher FI values and positive rates in lung cancer than those in non-cancer tissues ( P < 0. 01) . p21 alteration was independent from tumor size ,lymph node metastasis , TNM stage , differentiated grade and histological type. CD44v expression in stage II+III(83. 3 %) was much higher than that in stage I(29. 4 %) ( P < 0. 01) . As compared with lung cancer without lymph node metastasis (33. 3 %) , primary lung cancer with lymph node metastasis showed significantly higher expression rate of CD44v (81. 8 %) ( P < 0. 05) . Coexpression of p21 and CD44v had a distinct statistic significance ( P < 0. 01) .

CONCLUSIONS

Abnormality of p21 and CD44v may be involved in the carcinogenesis and development of lung neoplasms in coordination. Immunopositivity of CD44v may suggest a potential of high risk for lymph node metastasis in lung cancer.

Copper in plasma reflects its status and subsequent toxicity in the liver of LEC rats

The possible relation of the increase in the concentration of copper (Cu) in the bloodstream with the increased supply of Cu to ceruloplasmin in the liver was examined in relation to the onset of jaundice in Long-Evans rats with a cinnamon-like coat color (LEC rats), an animal model of Wilson disease. The Cu concentration in serum and that in liver, and then that in kidneys of LEC rats were correlated, and then the relationship between the Cu concentration in serum and the malondialdehyde (MDA) concentration in the liver, a marker for lipid peroxidation, and also the activities of alanine aminotransferase and lactate dehydrogenase, marker enzymes for liver damage, were examined. An increase in the Cu concentration in liver induced significant increases in the Cu concentrations in serum and kidneys, and their relationship was different before and after the onset of jaundice, as reflected by the concentration of Cu in serum (lower than 1.5 and higher than 2.7 micrograms/ml, respectively). The relationship between the MDA concentration in liver and the Cu concentration in serum showed a characteristic change between before and after the onset of jaundice. The marker enzymes for liver damage increased significantly with age, and showed distinct responses at the Cu concentration of 1.5-2.7 micrograms/ml in serum. The results suggest that the Cu concentration in plasma reflects the on-going biological and toxicological actions of non-MT-bound Cu in the livers of LEC rats.

Production of ascorbate and hydroxyl radicals in the liver of LEC rats in relation to hepatitis

The production of radicals was examined in vitro in liver supernatant prepared from LEC rats of different ages before and after the onset of jaundice. Each liver supernatant was subjected to heat-treatment at 90 degrees C for 10 min to remove heat-labile proteins, and then the production of radicals in the resultant supernatant in the presence of hydrogen peroxide and 5,5'-dimethyl-1-pyrroline oxide (DMPO) was studied by ESR. Two sharp ESR signals that completely decayed with time within 5 min after the addition of hydrogen peroxide were observed for the sample prepared from LEC rats before the onset of jaundice, followed by the appearance of four signals of a hydroxyl radical-DMPO adduct after 5 min. On the other hand, in the supernatant prepared from LEC rats after the onset of jaundice, the former two signals were not observed or observed only marginally, and the signals of the hydroxyl radical-DMPO adduct showed a different pattern of decay from that for the supernatant prepared from LEC rats before the onset of jaundice. With the addition of ascorbic acid to the liver supernatant prepared from LEC rats after the onset of jaundice, the former signals of the ascorbate and hydroxyl radicals reappeared. The present results suggest that ascorbate and hydroxyl radicals are produced in the liver of LEC rats with the onset of jaundice, depending on the relative ratio of ascorbic acid and cuprous ions.

Production of hydroxyl radicals by copper-containing metallothionein: roles as prooxidant

Production of hydroxyl radicals by copper (Cu)-containing metallothionein (MT) and its relation to zinc (Zn) bound to MT were studied in vitro with reference to the mechanism of the Cu toxicity in the liver of LEC rats. Zn-MT prepared from the liver of Zn-injected rats was reacted with cupric ions at various Cu/Zn ratios, and the concentrations of the two metals bound to MT and in the solution, valence states of Cu in the solution, production of hydroxyl radicals were determined. Cupric ions replaced Zn in MT after being reduced by thiol groups, and MT, worked as an antioxidant. Cupric ions added to MT that did not contain Zn were reduced to cuprous ions by thiol groups in Cu-MT, and the Cu bound to MT was liberated in a form of cuprous ions. Hydroxyl radicals were produced in the presence of hydrogen peroxide in proportion to the amount of cuprous ions liberated from MT. Cu-containing MT was proposed to work as a prooxidant until all thiol groups in MT were oxidized when Zn was not present in MT. The results indicate that MT works as an antioxidant as long as Zn is present in Cu-containing MT, while it works as a prooxidant when Zn is not present by liberating 1.5 M equivalents of cuprous ions relative to cupric ions added, and hydroxyl radicals are produced in the presence of hydrogen peroxide. On the other hand, MT not bound by Cu does not work as a prooxidant throughout.