•Stomata control carbon and water fluxes in leaves and help plant adapt environment.•We measured stomatal density (SD) and size (SS) for 181 species in Loess Plateau.•Stomatal traits differ across ...grassland types and plant functional groups.•The responses of stomata to the environment result from tradeoff between SD and SS.•The adaptation of stomata in adaxial epidermis to environment is regulated by SS.
The stomata control carbon and water vapor exchange between the leaves and atmosphere and may reflect plant adaptation to climate change to some extent. However, the spatial variation of stomatal traits on different sides of the leaves’ epidermis and their response to environmental changes remain unclear. Here, we measured stomatal density (SD), stomatal size (SS), and stomatal relative area (SRA) on both leaf surfaces of 181 plant species across an environmental gradient on the Loess Plateau. We calculated the proportion of stomatal traits between different epidermis surfaces of the leaves (abaxial and adaxial) and measured the total SD (SDtot), total SS (SStot), and total SRA (SRAtot) of the leaves as a whole. The SDtot, SStot, and SRAtot showed a log-normal distribution, differing across grassland types and plant functional groups, with a range of 22.57–890.09 stomata mm−2, 84.61–2022.81 μm2, and 0.51–43.71%, respectively. The SDtot, SStot, and SRAtot differed significantly between different grassland types. Meadow plants had larger SDtot, desert plants had larger SStot, and typical grassland plants had relatively larger SRAtot. The abaxial SD and SRA of the woody plants were significantly higher than those of herbaceous plants, but no significant differences were observed at the adaxial surface or for the overall leaf. A higher SDtot was correlated with a larger stomatal density ratio (R.SD) and smaller stomatal size ratio (R.SS). The R.SD, abaxial SD, abaxial SS, and adaxial SS were significantly correlated with environmental factors, but no such correlations were observed for the adaxial SD. These findings highlight the strong associations of stomatal traits with plant functional group and climate at a regional scale, representing the climatic adaptation strategies of stomatal traits across natural grassland communities.
Long-term continuous monoculture cropping of tobacco leads to high incidence of tobacco bacterial wilt (TBW) caused by Ralstonia solanacearum, which threatening world tobacco production and causing ...great economy loss. In this study, a safe and effective way to control TBW by microbial degradation of phenolic allelochemicals (PAs) was explored. Eleven kinds of PAs were identified from continuous tobacco cropping soil. These PAs exhibited various effects on the growth, chemotaxis and biofilm formation of R. solanacearum. Then we isolated eight strains of Bacillus, one strain of Brucella, one strain of Enterobacter and one strain of Stenotrophomonas capable of degrading these PAs. The results of degradation assay showed that these isolated strains could degrade PAs both in culture solutions and soil. Besides, the incidence of TBW caused by R. solanacearum and deteriorated by PAs were significantly decreased by treating with these degrading strains. Furthermore, six out of eleven isolated strains were combined to degrade all the identified PAs and ultimately sharply reduced the incidence of TBW by 61.44% in pot experiment. In addition, the combined degrading bacteria could promote the plant growth and defense response. This study will provide a promising strategy for TBW control in tobacco production.
Hg2+ has a significant hazardous impact on the environment and ecosystem. There is a great demand for new methods with high selectivity and sensitivity to determine mercury in life systems and ...environments. In this paper, a novel turn-on Hg2+ fluorescent probe has been reported with a naphthalimide group. The Hg2+ fluorescent probe was designed by the inspiration of the well-known specific Hg2+-triggered thioacetal deprotection reaction. A 1,2-dithioalkyl group was chosen as the specific recognition site of Hg2+. The probe showed weak fluorescence without Hg2+, and the color of the solution was light yellow. In the presence of Hg2+, the probe reacted specifically with the mercury ion to produce an aldehyde and emitted strong fluorescence, and the color of the solution also turned light green, thus realizing the monitoring of the mercury ion. The Hg2+ fluorescent probe showed outstanding sensitivity and selectivity toward Hg2+. Furthermore, the Hg2+ fluorescent probe could work in a wide pH range. The linear relationship between the fluorescence intensity at 510 nm and the concentration of Hg2+ was obtained in a range of Hg2+ concentration from 2.5 × 10–7 to 1.0 × 10–5 M. The detection limit was found to be 4.0 × 10–8 M for Hg2+. Furthermore, with little cell toxicity, the probe was successfully applied to the confocal image of Hg2+ in PC-12 cells.
This paper proposes an automated inspection approach for printed circuit boards (PCBs) that can accurately locate defects to solve the issues of low precision, complex equipment, and high cost. ...Digital image processing techniques are utilized in this method, including filtering, image segmentation, feature extraction, alignment, and mathematical morphology processing. To overcome the Otsu thresholding segmentation algorithm's high computational cost and poor real-time performance, a particle swarm approach is optimized to increase image segmentation efficiency. Meanwhile, combining the benefits of the FLANN algorithm and the SURF method, matching image feature points is done based on the SURF algorithm. The performance of matching image feature points is improved. In addition, the alignment error of the images is reduced. According to experimental results, the improved PCB defect detection algorithm demonstrated 98.9% accuracy, with remarkable efficiency and accuracy, and can satisfy PCB defect detection requirements.
Tobacco, a crop of significant economic importance, was greatly influenced in leaf quality by protein content. However, current processing parameters fail to adequately meet the requirements for ...protein degradation. Microorganisms possess potential advantages for degrading proteins and enhancing the quality of tobacco leaves, and hold substantial potential in the process of curing. To effectively reduce the protein content in tobacco leaves, thereby improving the quality and safety of the tobacco leaves. In this study, tobacco leaf were used as experimental material. From these, the BSP1 strain capable of effectively degrading proteins was isolated and identified as Bacillus subtilis by 16S rDNA analysis. Furthermore, the mechanisms were analyzed by integrating microbiome, transcriptome, and metabolome. Before curing, BSP1 was applied to the surface of tobacco leaves. The results indicated that BSP1 effectively improves the activity of key enzymes and the content of related substances, thereby enhancing protein degradation. Additionally, protein degradation was achieved by regulating the diversity of the microbial community on the surface of the tobacco leaves and the ubiquitin-proteasome pathway. This study provided new strategies for extracting and utilizing functional strains from tobacco leaves, opening new avenues for enhancing the quality of tobacco leaves.
Tobacco, a vital economic crop, had its quality post-curing significantly influenced by starch content. Nonetheless, the existing process parameters during curing were inadequate to satisfy the ...starch degradation requirements. Microorganisms exhibit inherent advantages in starch degradation, offering significant potential in the tobacco curing process. Our study concentrated on the microbial populations on the surface of tobacco leaves and in the rhizosphere soil. A strain capable of starch degradation, designated as BS3, was successfully isolated and identified as
by phylogenetic tree analysis based on 16SrDNA sequence. The application of BS3 on tobacco significantly enhanced enzyme activity and accelerated starch degradation during the curing process. Furthermore, analyses of the metagenome, transcriptome, and metabolome indicated that the BS3 strain facilitated starch degradation by regulating surface microbiota composition and affecting genes related to starch hydrolyzed protein and key metabolites in tobacco leaves. This study offered new strategies for efficiently improving the quality of tobacco leaves.
The structures of short fiber reinforced composites become designable from macroscopic to microscopic due to the advancement in additive manufacturing technologies. The diffuse ultrasonic wave ...inspection benefits from information from multiple scattering processes, which is suitable for the quality assurance of complex structures. This study established a two-dimensional wave propagation model assuming the decoupling of the fiber volume into the fiber distribution matrix in the plane and the local fiber fraction along the thickness axis. The k-space pseudospectral method was applied to calculate the diffuse wave fields. The defect inspection process was studied numerically based on the Locadiff technique for additive-manufactured short-fiber reinforced composites. The stretching method provided the same average distance but a smaller relative deviation to the defect than the doublet method. The localization resolution improved significantly for the initial increment of the number of transmitters; limited improvement can be achieved further. Localization results fluctuated when the transmitter combination groups were distant from the defect. This method worked well with the isotropic and quasi-isotropic plates, while an oversimplification was found for the unidirectional fiber structure.
As a key reactive oxygen species (ROS), hypochlorous acid (HClO) plays an important role in many physiological and pathological processes. The mitochondria-targeting probes for the highly sensitive ...detection of HClO are desirable. In present work, we designed and synthesized an original mitochondria-localizing and turn-on fluorescent probe for detecting HClO. 4-Aminonaphthalimide was employed as the fluorescent section, the (2-aminoethyl)-thiourea unit was utilized as a typical sensing unit, and the quaternized pyridinium moiety was used as a mitochondria-targeted localization group. When HClO was absent, the probe showed weak fluorescence. In the existence of HClO, the probe revealed a blue fluorescence. Moreover, the turn-on fluorescent probe was able to function in a broad pH scope. There was an excellent linearity between the fluorescence emission intensity at 488 nm and the concentrations of HClO in the range of 5.0 × 10–7 to 2.5 × 10–6 mol·L–1. Additionally, the probe had almost no cell toxicity and possessed an excellent mitochondria-localizing capability. Furthermore, the probe was able to image HClO in mitochondria of living PC-12 cells. The above remarkable properties illustrated that the probe was able to determine HClO in mitochondria of living cells.
Nitroxyl (HNO) is a member of the reactive nitrogen species, and how to detect it quickly and accurately is a challenging task. In this work, we designed and prepared a fluorescent ratiometric probe ...based on the fluorescence resonance energy transfer (FRET) mechanism, which can detect HNO with high selectivity. The coumarin derivative was used as an energy donor, the rhodol derivative was applied as an energy receptor, and 2-(diphenylphosphine)benzoate was utilized as the recognition group to detect nitroxyl. In the absence of HNO, the rhodol derivative exists in a non-fluorescent spironolactone state, and the FRET process is inhibited. Upon adding HNO, the closed spironolactone form is transformed into a conjugated xanthene structure and the FRET process occurs. This probe could specifically recognize nitroxyl, showing high sensitivity and selectivity. When the HNO concentration was changed from 3.0 × 10–7 to 2.0 × 10–5 mol·L–1, I 543nm/I 470nm exhibited a satisfactory linear correlation with the concentration of HNO. A detection limit of 7.0 × 10–8 mol·L–1 was obtained. In addition, almost no cell toxicity had been verified for the probe. The probe had been successfully applied to the ratiometric fluorescence imaging of HNO in HepG2 cells.
Hypochlorous acid (HOCl) was crucial for maintaining the homeostasis in cells and plays vital roles in many physiological and pathological processes. In this work, a highly selective fluorescent ...probe for hypochlorous acid in living cells was constructed and prepared based on a naphthalene derivative. A naphthalene derivative was utilized as the fluorescent group, and N,N-dimethylthiocarbamate was applied as the selective recognition site for HOCl. Before adding HOCl, the fluorescent probe exhibited weak fluorescence. Upon adding HOCl, the fluorescent probe displayed remarkable fluorescence enhancement. The fluorescence intensity at 502 nm showed a linear response to the concentration of HOCl from 3.0 × 10−7 to 1.0 × 10−5 mol·L−1. The detection limit was estimated to be 1.5 × 10−7 mol·L−1 for HOCl. The fluorescent probe showed fast response and outstanding selectivity toward HOCl. It owned good biocompatibility and had also been successfully applied in the confocal imaging of exogenous and endogenous HOCl in living cells.
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