Structure Of Stomata Research Articles

Bionic modified atmosphere film Inspired by plant stomata with curcumin as controllable gas “Switches” for fruit preservation

Modified atmosphere packaging (MAP) is a promising preservation technology for the fruits with the characteristics of respiration metabolism. However, traditional MAP cannot precisely control and regulate the selective permeation of gas. Inspired by the fact that plants control respiration through leaf stomata, we innovatively construct a bionic intelligent MAP of curcumin-porous starch/chitosan (Cur-PS/CS) with leaf stomata structure. Herein, PS is used as the bionic stomata, and Cur is used as the gas switch controlled by changing the pH and temperature. As a result, the CO2/O2 selectivity values are precisely controlled from 2.60 to 5.51 by controlling the amount of Cur released from PS. In which, the 10.3 % Cur-PS/CS displays the highest CO2/O2 selectivity value (5.51). In addition to outstanding tensile strength (51.54 MPa) and antioxidant activity (91.03 %), the inhibition zone diameters of 10.3 % Cur-PS/CS film against Escherichia coli, Staphylococcus aureus and Aspergillus niger reach 8 mm, 7.8 mm and 9.1 mm, respectively. Therefore, the 10.3 % Cur-PS/CS film effectively extends the shelf life of the non-climacteric fruit (cherries) and climacteric fruit (apple slices). More importantly it does not bring any issues with food safety and environmental contamination due to the excellent biodegradability of Cur-PS/CS film.

Superior Heat and Mass Transfer Performance of Bionic Wick with Finger-like Pores Inspired by the Stomatal Array of Natural Leaf.

The thermal management of electronics has gained significant attention, with loop heat pipes (LHPs) emerging as an attractive solution for heat dissipation. The heat transfer performance of LHPs is influenced by the heat and mass transfer processes within the wick. However, designing the pore diameter of the wick is challenging due to the different requirements of flow resistance and capillary force. Specifically, the working fluid needs large pores to reduce resistance, while the liquid suction requires small pores to provide a large capillary force. To address this issue, we drew inspiration from the stomatal array of natural leaves used for transpiration and developed an alumina ceramic bionic wick with finger-like pores using the phase-inversion tape casting method. The finger-like pores in the wick resemble the straight hole structure of stomata, which increases the gas-liquid interface area within the wick. This design allows for timely discharge of water vapor generated by boiling, thereby reducing mass transfer resistance. Additionally, numerous micrometer-sized small pores surrounding the finger-like pores provide sufficient capillary force to replenish liquid for the gas-liquid evaporation interface. Experimental results demonstrate that the introduction of finger-like pores in the wick increases gas and water permeabilities by 2.4 and 5.2 times, respectively. Furthermore, the superior heat and mass transfer performance of the bionic wick was demonstrated with an LHP. This work effectively addresses the conflicting demands of capillary force and flow resistance, enhancing the heat transfer performance of LHPs, which holds great promise for addressing heat dissipation challenges in high power density electronic chips and has potential applications in aviation, aerospace, and microelectronics for efficient thermal management.

Identification of Stomata Structures in Leaves of The Tradescantia Genus in The Meurandeh Langsa Region

Langsa City is a city located in the province of Nangroe Aceh Darussalam with an area of 262.41 km2 with a population of 165,890 people. Meurandeh Village is one of the villages located in Langsa city, precisely in Langsa Lama. Meurandeh is one of the places that produces plants from the Tradescantia genus. This research aims to identify and differentiate the stomata of three types of plants from the Tradescantia genus. The method used in this research is a qualitative method with observational data collection techniques. The results of this research show that the three types of plants from the Tradescantia genus have three neighboring cells and a tetracytic type of stomata. Of these three types of plants, there are differences in the shape and structure of the stomata.

Leaf‐Structure‐Inspired Through‐Hole Electrode with Boosted Mass Transfer and Photothermal Effect for Oxygen Evolution Reactions

AbstractThe sluggish kinetics of oxygen evolution reaction (OER) remains a bottleneck for the electrocatalytic water splitting. In addition to improving the intrinsic activity of electrocatalysts, the electrode structure and external environment also have a significant influence on catalytic performance. Inspired by photosynthesis in plant leaves, a photothermal conversion strategy is proposed via the decoration of photothermal responsive MoS2/FeCoNiS‐nanotube (MoS2/FeCoNiS‐NT) on designed through‐hole porous nickel foam (PNF), defined as MoS2/FeCoNiS‐NT@PNF, to boost OER performance. The PNF facilitated bubble transport in OER by mimicking stomata structure of the leaf, and simultaneously, the MoS2/FeCoNiS‐NT increases light absorption and photothermal conversion by simulating the leaf epidermis. Benefiting from bionic structure and functional design, the MoS2/FeCoNiS‐NT@PNF electrode exhibits highly effective oxygen‐evolving ability and excellent photothermal conversion capacity (surface temperature: 25 °C → 52.3 °C, AM1.5G), which increases the intrinsic activity of electrocatalysts. With the assistance of optimized electrode structure and the photothermal effect, the MoS2/FeCoNiS‐NT@PNF electrode exhibits a low overpotential of 214 mV to achieve 50 mA cm−2. This research reveals that tuning the electrode structure can promote light absorption in the electrolyte in favor of OER performance, which can serve as an inspiration for the development of high‐performance catalytic electrodes.

Circadian Clock Contributes to Modulate Salinity Stress-Responsive Antioxidative Mechanisms and Chloroplast Proteome in Spinacia oleracea

Extreme abiotic stresses such as drought, salinity, and temperature reduce crop productivity significantly and pose a serious threat to the area of land used for agriculture. Therefore, there is a pressing need to create crops that can thrive in these circumstances. It has been noted that plants can maintain defense mechanisms during any environmental changes and anticipate diurnal patterns correct to a circadian-based clock. Therefore, the main aim of this study was to investigate the role of circadian core oscillators in response to salinity stress in an important vegetable crop, spinach, and obtain evidence to better understand salinity stress adaptation for crop productivity. Therefore, the current study was carried out to examine the circadian clock-based (morning–evening loop) salinity stress defense mechanism in spinach (Spinacia oleracea), a leafy vegetable crop with significant economic importance and health benefits. In the presence of dawn and dusk, the circadian clock-based defense mechanism was observed using the genotypes “Delhi Green” and “Malav Jyoti.” A photoperiodic rhythm consists of 4-h intervals for 12 h (morning–evening loop) in spinach was demonstrated under the salinity stress treatments (20 mM and 50 mM). The clock-controlled a large fraction of growth parameters such as plant height, biomass, and root-shoot ratio under salinity stress. Conversely, salinity stress resulted in upregulation of antioxidative parameters such as superoxide dismutase, ascorbate peroxidase, catalase, and other stress markers such as thiobarbituric acid reactive substances, proline content, and localizations of H2O2 and O2−1 but was altered and maintained at a certain photoperiodic time interval of the circadian clock. In distinction to results observed from antioxidative measurements performed with an early and late circadian duration of salt-treated plants, 10 am and 2 pm were revealed to be the rhythmic times for controlling salinity stress. Likewise, comprehensive measurements of the photosynthetic system under salinity stress at specific photoperiodic circadian time intervals, including net-photosynthetic rate, transpiration, stomatal conductance, PSII quantum yield, and stomata structure, were made at 10 am and 2 pm. The salinity stress response was down-streamed and the clock also regulated chloroplastic protein expression. Thus, according to our findings, photoperiodic circadian rhythms, particularly the morning–evening loop, enhanced plant survival rates by modulating cellular antioxidant mechanisms and chloroplastic proteins that further helped to reduce the effects of salinity stress.

Struktur Stomata Pada Familia Poaceae Di Desa Kota Bumi Kecamatan Tanjung Lubuk Kabupaten OKI

Research on Stomata Structure in the Poaceae Family in Kota Bumi Village, Tanjung Lubuk District, Ogan Komering Ilir Regency, was carried out from April to May 2022. The purpose of the study was to examine the stomata structure on the adaxial (top) and abaxial (bottom) leaves of the Poaceae family. This study uses a descriptive survey method by going directly to the research location exploring the area of ​​Kota Bumi Village, Tanjung Lubuk District, Ogan Komering Ilir Regency. Sampling was done by direct observation observing the stomata structure of the adaxial (top) and abaxial (bottom) leaves of rice plants (Oryza sativa.), corn (Zea mays), reeds (Imperata cylindrica), sugarcane (Saccharum officinarum) and lemongrass ( Cymbopogon citratus). The results of the study found that 5 species had stomata located on the surface of the leaf Adaxia (top) and Abaxial (bottom) leaf. Amphistomatic type of stomatal spread. The shape of each guard cell is in the shape of a dumbbell. The number of neighboring cells is 2 neighboring cells. Both have the type of Stomata Graminae, the shape of the epidermal cells is elongated, grooved, rounded, parallel elongated, and grooved

Stomata in Close Contact: The Case of Pancratium maritimum L. (Amaryllidaceae).

A special feature found in Amaryllidaceae is that some guard cells of the neighboring stomata form a "connection strand" between their dorsal cell walls. In the present work, this strand was studied in terms of both its composition and its effect on the morphology and function of the stomata in Pancratium maritimum L. leaves. The structure of stomata and their connection strand were studied by light and transmission electron microscopy. FM 4-64 and aniline blue staining and application of tannic acid were performed to detect cell membranes, callose, and pectins, respectively. A plasmolysis experiment was also performed. The composition of the connection strand was analyzed by fluorescence microscopy after immunostaining with several cell-wall-related antibodies, while pectinase treatment was applied to confirm the presence of pectins in the connection strand. To examine the effect of this connection on stomatal function, several morphological characteristics (width, length, size, pore aperture, stomatal distance, and cell size of the intermediate pavement cell) were studied. It is suggested that the connecting strand consists of cell wall material laid through the middle of the intermediate pavement cell adjoining the two stomata. These cell wall strands are mainly comprised of pectins, and crystalline cellulose and extensins were also present. Connected stomata do not open like the single stomata do, indicating that the connection strand could also affect stomatal function. This trait is common to other Amaryllidaceae representatives.

Rapid In Vitro Propagation of Fig (Ficus carica L.) ‘Violette de Solliès’ Supported by Molecular and Microscopy Analyses

Ficus carica L. is a common fig that is an incredibly nutritional fruit, well-known for its medicinal and economic values. This study aims to establish an efficient protocol for the mass propagation of fig plantlets (Ficus carica L.) for the cultivar ‘Violette de Solliès’. Surface-sterilized shoot-tip explants were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations of cytokinins (6-benzylaminopurine, BAP; thidiazuron, TDZ; kinetin, Kn; and zeatin, Zea). Induced shoots were rooted on Woody Plant Medium (WPM) with different concentrations of auxins (naphthalene-acetic acid, NAA; indole-3-acetic acid, IAA; and indole-3-butyric acid, IBA). Rooted explants were acclimatized in eight different soil substrates prior to cultivation in a commercial plot. The propagated plantlets were analyzed for genetic stability and clonal fidelity using RAPD and SCoT molecular markers, whereas scanning electron microscopy (SEM) was performed to observe the stomata morphology of post-acclimatized plants. MS media supplemented with 5.0 mg/L BAP was the optimal treatment for multiple shoot induction (15.20 ± 1.03 shoots), whereas the highest percentage of rooting (93.33%) was achieved in WPM supplemented with 3.0 mg/L IBA. Plantlets were successfully acclimatized in biochar soil with a survival rate of 100%. RAPD and SCoT analysis showed no polymorphism occurrences across six subculture cycles, whereas observations via SEM indicated normal stomata structures on the leaves of acclimatized plantlets. This study documents an efficient micropropagation protocol for Ficus carica cv. ‘Violette de Solliès’ for the production of uniformed and true-to-type plant stocks suitable for commercial propagation.

Study on the Effect of Jujube Powder on the Quality of Bread

As a traditional Chinese medicine and food, jujube is rich in minerals, dietary fiber, polysaccharides, vitamins and other healthy nutrients, which are the supplemental nutrition to wheat flour. This paper studied the bread quality with jujube powder and determined the appropriate ratio of jujube powder to wheat flour. The related characteristics of bread with jujube powder were analyzed by Electronic nose (E-nose), solid phase micro-extraction gas chromatography-mass spectrometry (SPME-GC-MS), scanning electron microscope, texture analyzer, and Sensory Texture Evaluation Methodology, respectively. The total phenolic content and antioxidant activity of the finished bread were evaluated. The results showed that with the increase of the addition of jujube powder, the specific volume, moisture content and elasticity of bread decreased gradually, while the softness and chewiness were increased progressively. The total phenol content and antioxidant activity of bread increased gradually with the adding of jujube powder content. The bread quality was the best when the addition of 4g of jujube powder/100g of wheat flour. While new volatile substances of jujube bread included hexane, 2, 3-dihydro-3, 5-dihydroxy-6-methyl-4H-phyran-4-one, n-Hexadecane, and l- Caryophyllene, as well as alcohol. Microstructural analysis showed that the structure of stomata changed significantly with the adding of jujube powder. The size of stomata and density of bread are not significantly different from those of ordinary bread with less than 4% jujube powder.

Impact of foliar spray of zinc oxide nanoparticles on the photosynthesis of Pisum sativum L. under salt stress

This study investigates the impacts of zinc oxide nanoparticles: bare (ZnO NPs) and ZnO NPs coated with silicon shell (ZnO-Si NPs), on Pisum sativum L. under physiological and salt stress conditions. The experimental results revealed that the foliar spray with ZnO-Si NPs and 200 mg/L ZnO NPs did not influence the stomata structure, the membrane integrity, and the functions of both photosystems under physiological conditions, while 400 mg/L ZnO-Si NPs had beneficial effects on the effective quantum yield of photosystem II (PSII) and the photochemistry of photosystem I (PSI). On the contrary, small phytotoxic effects were registered after spraying with 400 mg/L ZnO NPs accompanied by stimulation of the cyclic electron flow around PSI and an increase of the non-photochemical quenching (NPQ). The results also showed that both types of NPs (with exception of 400 mg/L ZnO NPs) decrease the negative effects of 100 mM NaCl on the photochemistry of PSI (P700 photooxidation) and PSII (qp, Fv/Fm, Fv/Fo, ΦPSII, Φexc), as well as on the pigment content, stomata closure and membrane integrity. The protective effect was stronger after spraying with ZnO-Si NPs in comparison to ZnO NPs, which could be due to the presence of Si coating shell. The role of Si shell is discussed.

The Alkali Tolerance of Broomcorn Millet (Panicum miliaceum L.) at the Germination and Seedling Stage: The Case of 296 Broomcorn Millet Genotypes.

Broomcorn millet (BM), one of the earliest domesticated cereal crops originating in northern China, can tolerate extreme conditions, such as drought and high temperatures, which are prevalent in saline-alkali, arid, and barren landscapes. However, its adaptive mechanism to alkali stress is yet to be comprehensively understood. In this study, 80 and 40 mM standard alkali stress concentrations were used to, respectively, evaluate the alkali tolerance at the germination and seedling stages of 296 BM genotypes. Principal component analysis (PCA), Pearson's correlation analysis, and F-value comprehensive analysis were performed on the germination parameters (germination potential, germination index, germination rate, vigor index, root length/weight, sprout length/weight, and alkali damage rate). Based on their respective F-values, the BM genotypes were divided into five categories ranging from highly alkali resistant to alkali sensitive. To study the response of seedlings to alkaline stress, we investigated the phenotypic parameters (plant height, green leaf area, biomass, and root structure) of 111 genotypes from the above five categories. Combining the parameters of alkali tolerance at the germination and seedling stages, these 111 genotypes were further subdivided into three groups with different alkali tolerances. Variations in physiological responses of the different alkali-tolerant genotypes were further investigated for antioxidant enzyme activity, soluble substances, malondialdehyde (MDA) content, electrolyte leakage rate, and leaf structure. Compared with alkali-sensitive genotypes, alkali-tolerant genotypes had high antioxidant enzyme activity and soluble osmolyte content, low MDA content and electrolyte leakage rate, and a more complete stomata structure. Taken together, this study provides a comprehensive and reliable method for evaluating alkali tolerance and will contribute to the improvement and restoration of saline-alkaline soils by BM.

Grain evolution simulation of ceramic tool material in spark plasma sintering process based on an improved cellular automata model

In this paper, a mathematical model for simulating the grain evolution process of ceramic materials was constructed to investigate the effects of the sintering parameters on the microstructure in the spark plasma sintering process. Firstly, a new algorithm of removing the right angle of grain was improved and an improved cell state assignment method was proposed based on the cellular automata model. Then the sintering parameters were coupled into the model, and the simulation method of grain growth and pore evolution were proposed. Finally, a ceramic material grain evolution model with stomata structure for spark plasma sintering was constructed. The simulation results showed that the grain size increased exponentially with the increases of holding time and sintering temperature, while the pores gradually decreased with the increase of the two parameters and the density of the material. Besides, the uniformity of grain growth also decreased with the increase of holding time. These results conformed to the topological characteristics of grain growth and the law of grain boundary migration, and can provide support for the sintering parameters optimization of ceramic tool materials.

Determination of Stoma Density and Distribution of Hazelnut (Corylus avellana L.) Cultivars and Genotypes Grown in Different Ecologies

Bu çalışmada, iki farklı ekoloji olan Trabzon ve Hizan (Bitlis) ilçesinde yetiştirilen 11 fındık çeşidi ve tipinin yapraklarındaki stoma sayıları ve dağılımı incelenmiştir. Stomalar, hipostomatik olarak sadece yaprak alt yüzeyinde gözlenmiştir. Stoma sayısı birim alanda (mm2) 90.00 (Turşink) ile 111.60 (Himdi) adet arasında değişim göstermiştir. Çeşitlerin stoma uzunluğu ve genişliği 23.31 (Herişte) - 32.03 (Foşa) ve 19.20 (Cavreş) - 26.78 (Foşa) aralığında belirlenmiştir. Stoma uzunluğu ve genişliği açısından üst değerler Foşa fındık çeşidinde belirlenmiştir. Fındık çeşitleri ve türleri arasında Himdi en yüksek stoma indeksine (%19.43) sahipken Cavreş en düşük stoma indeksine (%13.26) sahiptir. Çeşit ve tiplerin yaprak epidermis hücrelerinin sayısı 462.82 ile 612.46 adet / mm2 arasında değişim göstermiştir. Stoma sayısı ile stoma uzunluğu (-0.684-0.358) ve stoma genişliği (-0.706-0.856) arasında negatif korelasyonlar bulunmuştur. Bu sonuçlar, fındık çeşitlerinin ve genotiplerin farklı stoma özelliklerine sahip olduğunu göstermiştir. Fındıklarda stoma yapılarının belirlenmesinde en iyi yöntemin saydamlaştırma yöntemi olduğu gözlemlenmiştir.

Deciphering the Novel Role of AtMIN7 in Cuticle Formation and Defense against the Bacterial Pathogen Infection.

The cuticle is the outermost layer of plant aerial tissue that interacts with the environment and protects plants against water loss and various biotic and abiotic stresses. ADP ribosylation factor guanine nucleotide exchange factor proteins (ARF-GEFs) are key components of the vesicle trafficking system. Our study discovers that AtMIN7, an Arabidopsis ARF-GEF, is critical for cuticle formation and related leaf surface defense against the bacterial pathogen Pseudomonas syringae pathovar tomato (Pto). Our transmission electron microscopy and scanning electron microscopy studies indicate that the atmin7 mutant leaves have a thinner cuticular layer, defective stomata structure, and impaired cuticle ledge of stomata compared to the leaves of wild type plants. GC–MS analysis further revealed that the amount of cutin monomers was significantly reduced in atmin7 mutant plants. Furthermore, the exogenous application of either of three plant hormones—salicylic acid, jasmonic acid, or abscisic acid—enhanced the cuticle formation in atmin7 mutant leaves and the related defense responses to the bacterial Pto infection. Thus, transport of cutin-related components by AtMIN7 may contribute to its impact on cuticle formation and related defense function.

Stomatal Response of Maize (Zea mays L.) to Crude Oil Contamination in Soils

In this study, maize plant was cultured in soil contaminated with different levels of crude oil. The purpose was to investigate the change of soil properties, leaf physiological and chemical parameters, and phenanthrene content in the leaf. Results showed that soil water content significantly increased when the levels of total petroleum hydrocarbons were 3700–17,800 mg/kg in soil, and soil electrical conductivity significantly increased compared with the control. In maize leaf, stomatal length and density, as well as K and Na contents decreased in contaminated treatments compared with the control. Stomatal length has a significant positive correlation with K content in leaf (r = 0.92, p < 0.01), while stomatal density was negatively correlated to the crude oil level in soil (r = −0.91, p < 0.05). Accumulation of phenanthrene in maize leaf was mainly through the foliar uptake pathway. Phenanthrene concentrations of maize leaf in oil-treated soil were less than that of the control, which exhibited a significant positive relationship with stomatal length (r = 0.98, p < 0.01). This study demonstrated that the stomata structure of maize could be influenced by crude oil and thus possibly controlling the accumulation of polycyclic aromatic hydrocarbons in aerial tissues. Based on these results, controlling stomata movement will be beneficial to phytoremediation of contaminated soil.

KARAKTERISTIK STOMATA PADA POHON DI RUANG TERBUKA HIJAU UNIVERSITAS TANJUNGPURA KOTA PONTIANAK

The purpose of this study was to describe the stomata found in pulai, mahang, saga, white meranti and ketapang plants in the green space area. This study uses a descriptive method to describe stomatal characteristics such as stomatal type, stomata size and number of stomata in perennials, mahang, saga, ketapang and white meranti. The study was conducted in two green open areas, namely the Untara Sylva Arboretum and in the public green open area. Length of stomata observation for 2 weeks. Overall the results of the observations obtained 4 (four) types of stomata that are the same in the two regions. The types of stomata are anisocytic in Pulai (Alstonia scholaris), anomosytic in mahang (Macaranga pruinosa), parasitic in saga (Adenanthera pavonina), pickled on white meranti (Shorea bracteolata), anisocytic on ketapang (Terminalia cattapa). In the Sylva Arboretum area, Untan, plant origin has a stomata number of 15 with stomata size of 14.1 μm, stomatal hole 8.03 μm and neighboring cells 14.7 μm. In the green open space area of the plant, there were ketapang plants had 35 stomata with a stomata size of 16.03 μm, a stomata hole of 8.03 and a neighboring cell of 6.57. the stomata structure shows that the leaves found in the arboretum region have large stomata while the outside of the general green open space has a small stomata. Different conditions of light and temperature greatly influence the variation in numbers on the size of the stomata, stomatal holes and neighboring cells. The farther the distance between plants and crowded places the more the size of the stomata decreases.Keywords: green open space, number of stomata, stomatal types, trees

STRUKTUR STOMATA DAUN BEBERAPA TUMBUHAN KANTONG SEMAR (Nepenthes spp.)

The exploitation of pitcher plants (Nepenthes spp.) for economics interest and forest degradation make a higher extinction risk for Nepenthes globally. This research was aimed to examine anatomical structure of stomata of Nepenthes gracilis, N. reinwardtiana, N. ampullaria. The result showed that the type of stomata of N. gracilis and N. reinwardtiana has the actinocitic type while, N. ampullaria has anomocitic stomata type.

Pengaruh Polutan Terhadap Struktur Morfologi Stomata Daun Trembesi (Samanea saman (Jacg) Merr)

Trembesi (Samanea saman) is one of the plants that is currently developed as one of the green line plants. Stomata as part of the leaf that has the ability to bind air, especially oxygen and carbon dioxide, is one part of the plant that can be used as an indicator to see the effect of pollutants contained in the air. The result was obtained by using an electron microscope to analyze the morphological structure of stomata leaves Trembesi (Samanea saman). Location was determined by two groups, the control group was at the UKI campus environment which was away from air pollution and the treatment group was in the Cawang police station where many vehicles passed through. Within a 90 days after treatment of pollutant exposure to plants, the structure of Trembesi leaf stomata was observed using an electron microscope. Based on the observation, the leaf position in the middle of the tree and the position of the leaf at the bottom of the tree, it was found that the leaves placed in the control position had a finer stomata mouth structure, more leaf hairs, and a wider diameter. While on the leaves that are placed on the location exposed to pollutants, has an irregular leaf mouth structure, fewer leaf feathers, and smaller diameter. This study can be concluded that there was an effect of exposure of pollutant that could change morphology of stomata leaves of Trembesi (Samanea saman).

Effects of dust on forest tree health in Zagros oak forests.

Dust is one of the most devastating factors for the environment threatening all animal and plant species. In many regions, the ecological and economic impact of microdust on scarce species is critical. In the western region of Iran, the Zagros forests have been exposed to dust storms for many years. In this study, the effect of dust on oak trees, the most important trees of Zagros forests, is investigated. For this purpose, 3-year-old seedlings of three species of oak trees under natural conditions were exposed to dust during spring and summer months. Seedlings were divided into two groups; one group was assigned as dust treatment and the other as control that the control group washed regularly to remove dust. Anatomical characteristics of leaves and dust deposits on leaves during the study period were examined by scanning electron microscope (SEM). The rate of photosynthesis and gas exchange in control and treated plants was examined by IRGA, LCI. SEM images showed that stomata structure, trichome density, and epicuticular waxes of leaves are different in all three species. This difference in micromorphology of species influences the effects of dust deposited on the leaves. A comparison of leaf species images in control and dust treatment showed that in dust treatment the percentage of stomata blocked by dust in three species (per unit area) of Quercus infectoria, Q. libni, and Q. brantii were 61/6, 48/4, and 38/1%, respectively. The results of leaf gas exchange investigation indicated that stomatal occlusion by dust had a negative impact on the examined parameters of three oak species (P≤0.01). Thus, gas exchange and photosynthetic rates of the treated species were significantly reduced. The results of both parts of the study showed the vulnerability of the three species to dust as Q. infectoria>Q. libni>Q. brantii. Therefore, based on these findings, dust can disrupt the physiological activities of the studied species and the continuation of the exposure to dust will accelerate the process of destruction of these forests.

The desert plant Phoenix dactylifera closes stomata via nitrate‐regulated SLAC1 anion channel

Date palm Phoenix dactylifera is a desert crop well adapted to survive and produce fruits under extreme drought and heat. How are palms under such harsh environmental conditions able to limit transpirational water loss? Here, we analysed the cuticular waxes, stomata structure and function, and molecular biology of guard cells from P.dactylifera. To understand the stomatal response to the water stress phytohormone of the desert plant, we cloned the major elements necessary for guard cell fast abscisic acid (ABA) signalling and reconstituted this ABA signalosome in Xenopus oocytes. The PhoenixSLAC1-type anion channel is regulated by ABA kinase PdOST1. Energy-dispersive X-ray analysis (EDXA) demonstrated that date palm guard cells release chloride during stomatal closure. However, in Cl- medium, PdOST1 did not activate the desert plant anion channel PdSLAC1 perse. Only when nitrate was present at the extracellular face of the anion channel did the OST1-gated PdSLAC1 open, thus enabling chloride release. In the presence of nitrate, ABA enhanced and accelerated stomatal closure. Our findings indicate that, in date palm, the guard cell osmotic motor driving stomatal closure uses nitrate as the signal to open the major anion channel SLAC1. This initiates guard cell depolarization and the release of anions together with potassium.