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Correlations between lignin content and structural robustness in plants revealed by X-ray ptychography
摘要： Lignin is a heterogeneous aromatic polymer responsible for cell wall stiffness and protection from pathogen attack. However, lignin represents a bottleneck to biomass degradation due to its recalcitrance related to the natural cell wall resistance to release sugars for fermentation or further processing. A biological approach involving genetics and molecular biology was used to disrupt lignin pathway synthesis and decrease lignin deposition. Here, we imaged three-dimensional fragments of the petioles of wild type and C4H lignin mutant Arabidopsis thaliana plants by synchrotron cryo-ptychography. the three-dimensional images revealed the heterogeneity of vessels, parenchyma, and fibre cell wall morphologies, highlighting the relation between disturbed lignin deposition and vessel implosion (cell collapsing and obstruction of water flow). We introduce a new parameter to accurately define cell implosion conditions in plants, and we demonstrate how cryo-ptychographic X-ray computed tomography (cryo-PXCT) provides new insights for plant imaging in three dimensions to understand physiological processes.
关键词： lignin,structural robustness,X-ray ptychography,cryo-PXCT,plants,Arabidopsis thaliana
更新于2025-09-23 15:19:57
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Terahertz Spectroscopy of Different Phenotypes of Arabidopsis Thaliana
摘要： The recent surge in ‘Precision agriculture’ is fueled by the acute need of food security felt worldwide to feed the global burgeoning population. To this effect, various optical techniques have recently been employed to characterize the biochemical processes in various parts of the plants [1]. Terahertz (THz) region (0.3 – 10 THz) has gathered momentum in this field as it is biologically safe, can penetrate food packaging and most importantly, has fingerprinting ability of various organic and inorganic molecules due to active rotational and vibrational modes [2]. Moreover, unlike other optical spectroscopic techniques, THz time domain spectroscopic (THz-TDS) technique records the information in form of THz electric field; which once converted to frequency domain provides both amplitude and phase information [3]. Additionally, THz waves are highly absorbed by water which in turn can be utilized for quantitative water status monitoring in plants [4]. In this work, we have used THz-TDS with a bandwidth over 5 THz for the detection of biochemicals present in two different T-DNA insertion mutants in two independent genes of Arabidopsis thaliana (Col-0 Columbia ecotype). The plants were grown from mutant seeds in controlled environment. For easier optical access to all parts of the plants, the seedlings were grown parallel to the surface in a petri dish of plant growth medium. Liu et al. has already reported successful discrimination of transgenic Soybean seeds using THz spectroscopy [5]. We have recorded spectroscopic data of several parts of all the mutant plants which were 5, 7, 12 and 13 days old kept under identical conditions. The time domain spectrum obtained from the experiment was converted to frequency domain. Figure 1 shows the frequency domain spectrum of one such set of spectroscopic data collected from the stem part of the two different mutants compared to wild type control Col-0 plants. As it is evident from the spectrum, there are many absorption peaks corresponding to water and other biochemical molecules. For example, the peaks at 1.7 THz and 2.6 THz corresponds to sucrose present in the plants and in the nutri-solution which has been taken as the reference [2]. Our ongoing study involves careful analysis of the variations of the molecular absorption peaks for different mutants which would not only enable a label-free genetic identification, but also would help in our understanding of the underlying shift in biochemical processes contributed by the specific gene.
关键词： Terahertz spectroscopy,Arabidopsis thaliana,THz-TDS,Precision agriculture,biochemical processes
更新于2025-09-16 10:30:52
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Cadmium sulfide quantum dots impact Arabidopsis thaliana physiology and morphology
摘要： The differential mechanisms of CdS QDs (Quantum Dots) and Cd ion toxicity to Arabidopsis thaliana (L.) Heynh were investigated. Plants were exposed to 40 and 60 mg L-1 for CdS QDs and 76.9 and 115.2 mg L-1 CdSO4·7H2O and toxicity was evaluated at 5, 20, 35 (T5, T20, T35) days after exposure. Oxidative stress upon exposure was evaluated by biochemical essays targeting non-enzymatic oxidative stress physiological parameters, including respiration efficiency, total chlorophylls, carotenoids, ABTS and DPPH radicals reduction, total phenolics, GSH redox state, lipid peroxidation. Total Cd in plants was measured with AAS. Root and leaf morphology and element content were assessed in vivo utilizing low-vacuum Environmental Scanning Electron Microscopy (ESEM) with X-ray microanalysis (EDX). This integrated approach allowed identification of unique nanoscale CdS QDs toxicity to the plants that was distinct from CdSO4 exposure. The analyses highlighted that CdS QDs and Cd ions effects are modulated by the developmental stage of the plant, starting from T20 till T35 the plant development was modulated by the treatments, in particular CdS QDs induced early flowering. Both treatments induced Fe accumulation in roots, but at different intensities, while CdS QDs was associated with Mn increase into plant leaf. CdSO4 elicited higher levels of oxidative stress compared with QDs, especially the former treatment caused more intense respiration damages and reduction in chlorophyll and carotenoids than the latter. The two types of treatments impact differently on root and leaf morphology.
关键词： oxidative stress,morphology,Arabidopsis thaliana,Iron,ESEM/EDX,CdS QDs
更新于2025-09-12 10:27:22
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Controlled Growth of CH <sub/>3</sub> NH <sub/>3</sub> PbBr <sub/>3</sub> Perovskite Nanocrystals via a Water-Oil Interfacial Synthesis Method
摘要： Perturbation of the cellular redox state by stress conditions is sensed by redox-sensitive proteins so that the cell can physiologically respond to stressors. However, the mechanisms linking sensing to response remain poorly understood in plants. Here we report that the transcription factor bZIP68 underwent in vivo oxidation in Arabidopsis cells under oxidative stress which is dependent on its redox-sensitive Cys320 residue. bZIP68 is primarily localized to the nucleus under normal growth conditions in Arabidopsis seedlings. Oxidative stress reduces its accumulation in the nucleus and increases its cytosolic localization. Chromatin immunoprecipitation followed by sequencing (ChIP-seq) revealed that bZIP68 primarily binds to promoter regions containing the core G-box (CACGTG) or G-box-like motif of the genes involved in abiotic and biotic stress responses, photosynthesis, biosynthetic processes, and transcriptional regulation. The bzip68 mutant displayed slower growth under normal conditions but enhanced tolerance to oxidative stress. The results from the ChIP-seq and phenotypic and transcriptome comparison between the bzip68 mutant and wildtype indicate that bZIP68 normally suppresses expression of stress tolerance genes and promotes expression of growth-related genes, whereas its inactivation enhances stress tolerance but suppresses growth. bZIP68 might balance stress tolerance with growth through the extent of its oxidative inactivation according to the environment.
关键词： Arabidopsis thaliana,bZIP68,seedling growth,oxidative stress,transcriptional regulation
更新于2025-09-11 14:15:04
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A FRET sensor for live-cell imaging of MAP kinase activity in Arabidopsis
摘要： The catalytic activity of mitogen activated protein kinases (MAPKs) is dynamically modified in plants. Since MAPKs have been shown to play important roles in a wide range of signaling pathways, the ability to monitor MAPK activity in living plant cells would be valuable. Here we report the development of a genetically encoded MAPK activity sensor for use in Arabidopsis thaliana. The sensor is composed of yellow and blue fluorescent proteins, a phosphopeptide binding domain, a MAPK substrate domain, and a flexible linker. Using in vitro testing, we demonstrated that phosphorylation causes an increase in the F?rster resonance energy transfer (FRET) efficiency of the sensor. FRET efficiency can therefore serve as a readout of kinase activity. We also produced transgenic Arabidopsis lines expressing this sensor of MAPK activity (SOMA) and performed live-cell imaging experiments using detached cotyledons. Treatment with NaCl, the synthetic flagellin peptide flg22, and chitin all led to rapid gains in FRET efficiency. Control lines expressing a version of SOMA in which the phosphosite was mutated to an alanine did not show any substantial FRET changes. We also expressed the sensor in a conditional loss-of function double-mutant line for the Arabidopsis MAPK genes MPK3 and MPK6. These experiments demonstrated that MPK3/6 are necessary for the sensor’s NaCl-induced FRET gain, while other MAPKs are likely contributing to the chitin and flg22-induced FRET increases. Taken together, our results suggest that SOMA is able to dynamically report MAPK activity in living plant cells.
关键词： Arabidopsis thaliana,FRET sensor,live-cell imaging,MAP kinase
更新于2025-09-09 09:28:46
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Tracking Gene Expression via Light Sheet Microscopy and Computer Vision in Living Organisms
摘要： Automated tracking of spatiotemporal gene expression using in vivo microscopy images have given great insight into understanding developmental processes in multicellular organisms. Many existing analysis tools rely on the fluorescent tagging of cell wall or cell nuclei localized proteins to assess position, orientation, and overall shape of an organism; information necessary for determining locations of gene expression activity. Particularly in plants, organism lines that have fluorescent tags can take months to develop, which can be time consuming and costly. We propose an automated solution for analyzing spatial characteristics of gene expression without the necessity of fluorescent tagged cell walls or cell nuclei. Our solution indicates, segments, and tracks gene expression using a fluorescent imaging channel of a light sheet microscope while determining gene expression location within an organism from a Brightfield (non-fluorescent) imaging channel. We use the images obtained from the Arabidopsis thaliana root as a proof of concept for our solution by studying the effects of heat shock stress on CYCLIN B1 protein production.
关键词： computer vision,CYCLIN B1,light sheet microscopy,gene expression,Arabidopsis thaliana
更新于2025-09-09 09:28:46
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Identification and characterization of a core set of <scp>ROS</scp> wave‐associated transcripts involved in the systemic acquired acclimation response of Arabidopsis to excess light
摘要： Systemic acquired acclimation (SAA) plays a key role in optimizing growth and preventing damages associated with fluctuating or abrupt changes in the plant environment. To be effective, SAA has to occur at a rapid rate and depend on rapid signaling pathways that transmit signals from affected tissues to all parts of the plant. Although recent studies identified several different rapid systemic signaling pathways that could mediate SAA, very little is known about the extent of their involvement in mediating transcriptomic responses. Here we reveal that the systemic transcriptomic response of plants to excess light stress is extensive in its context and involves an early (2 minute) and transient stage of transcript expression that includes thousands of genes. This early response is dependent on the respiratory burst oxidase homolog D protein, and the function of the reactive oxygen species (ROS) wave. We further identify a core set of transcripts associated with the ROS wave and suggest that some of these transcripts are involved in linking ROS with calcium signaling. Priming of a systemic leaf to become acclimated to a particular stress during SAA involves thousands of transcripts that display a rapid and transient expression pattern driven by the ROS wave.
关键词： Arabidopsis thaliana,H2O2 signaling,systemic signaling,Reactive oxygen species (ROS) wave,Transcriptomics,light stress,MYB30,systemic acquired acclimation (SAA),WRKY
更新于2025-09-09 09:28:46