Silicon (Si) is the most copious element of existence in the lithosphere but still it has not been added into the essential element list. The imperative role of Si in triggering growth and ...development of plants has been identified. It is of paramount importance in regulating overall physiological and metabolic characteristics of the plants. Being considered as a non-essential element, it has been known to occur at about 30%, majority of its presence is there in rocks as mineral salts. It has been regarded as multitalented or quasi-element on earth's crust that can be efficiently taken up by plants and translocated further towards aerial parts via transpiration phenomenon. It has also been known to mitigate different biotic and abiotic stressed conditions from plants as the need of the hour owing to its eco-friendly nature. However, the mechanisms associated with their stress attenuation are associated with Reactive Oxygen Species (ROS) scavenging, activation of antioxidative defense responses and phytohormonal signaling. Also, biotic stress factors can be ameliorated through accumulation of Si within epidermal tissues or pathogenesis-related host defense mechanisms. To explore further, omics-mediated studies have been further discussed to shed light on the stress mitigating processes. Further, to improve our understanding for Si-mediated benefits in plants we need to explore the molecular mechanisms of Si uptake, transport and gene expression studies revealing their mitigate properties. In the present review, we have evolved the Si-based studies in plants associated with its transport, uptake and accumulation. Apart from this, we have also discussed about their role in ameliorating stresses from plants by activating their defenses. Moreover, their roles in plant hormonal crosstalk have also been elucidated. Above all, we have also revealed the role of Si-Nanoparticles (SiNPs) in improving stress potential of plants along with stimulation of plant productivities via omics-based approaches.
Plants encounter various abiotic stresses due to their sessile nature which include heavy metals, salt, drought, nutrient deficiency, light intensity, pesticide contamination, as well as extreme ...temperatures. These stresses impose major constraints limiting crop production and food security worldwide. Abiotic stresses primarily reduce the photosynthetic efficiency of plants, due to their negative consequences on chlorophyll biosynthesis, performance of the photosystems, electron transport mechanisms, gas exchange parameters, and many others. A better understanding of the photochemistry of plants under these abiotic stresses can help in the development of pragmatic interventions for managing these stresses. Interestingly, in this review, we provide an overview of insight into different mechanisms affecting the photosynthetic ability of plants in relation to these abiotic factors. The present review describes how different abiotic stresses can pose deleterious impacts on plant photosynthetic machinery including cellular membranes, cell division and cell elongation, biosynthesis of photosynthetic pigments, as well as electron transport chain. It is important to understand the detrimental impacts of various abiotic stresses for better stress management because a comprehensive understanding of plant responses has pragmatic implication for remedies and management.
Plant growth promoting rhizobacteria (PGPRs) are very effective in immobilization of heavy metals and reducing their translocation in plants via precipitation, complex formation and adsorption. The ...present study was therefore designed to understand the role of Pseudomonas aeruginosa and Burkholderia gladioli in mitigation of Cd stress (0.4 mM) in 10-days old L. esculentum seedlings. The present work investigated growth characteristics, photosynthetic pigments, metal tolerance index, metal uptake and the contents of metal chelating compounds (protein bound and non-protein bound thiols, total thiols) in microbes inoculated Cd treated L. esculentum seedlings. The gene expression profiling of different metal transporters was conducted in order to investigate the quantitative analysis. Our results revealed Cd generated toxicity in seedlings in terms of reduced growth (root length, shoot length and fresh weight) and photosynthetic pigments (chlorophyll, carotenoid and xanthophyll) which enhanced upon inoculations of P. aeruginosa and B. gladioli. Further, the metal uptake along with levels of protein and non-protein bound thiols was also enhanced in Cd-treated seedlings. Gene expression studies suggested enhanced expression in the metal transporter genes which were further declined in the microbe supplemented seedlings. Therefore, micro-organisms possess growth promoting traits that enable them to reduce metal toxicity in plants.
Cadmium (Cd) is considered to be one of the most toxic pollutants persistent in soil for thousands of years and is ranked on seventh position among all environmental pollutants. The higher ...concentration of Cd in plants inhibits their growth and metabolism and further enters the food chain. Cd toxicity initiates redox actions in plants by inducing oxidative stress through the production of free radicals. It alters mineral uptake by disturbing water potential or affects the microbial population in soils, opening and closing of stomata, transpiration, photosynthesis, antioxidant levels, sugar metabolism and productivities. It also causes chlorosis, mineral deficiencies, inhibition of nitrate reductase activity and ammonia assimilation in several plant species. The plants have adopted a number of mechanisms to facilitate reduction in the amount of ROS. They possess series of antioxidative defence responses to scavenge reactive oxygen species (ROS) levels. Furthermore, specific mechanisms such as such as efflux, immobilization, stabilization, complexation, sequestration and detoxification are generally observed to combat the Cd stresses. Moreover, endogenous phytohormonal signalling during stressed conditions within plants has also been focussed. Cd stimulates various hormonal signalling pathways and regulates many physiological processes in plants that in turn ameliorate Cd stress. Strikingly, phytohormones play an imperative role during signal transduction pathway along with regulating overall growth and development of plants under toxic conditions. Moreover, plant hormones boost antioxidant activities and plummet oxidative damage from plants along with maintaining cellular homeostasis. This review encompasses the ecotoxicological aspects of Cd within plants and plant responses to tackle such adversities.
The Gram-positive bacterium
can divide via two modes. During vegetative growth, the division septum is formed at the midcell to produce two equal daughter cells. However, during sporulation, the ...division septum is formed closer to one pole to yield a smaller forespore and a larger mother cell. Using cryo-electron tomography, genetics and fluorescence microscopy, we found that the organization of the division machinery is different in the two septa. While FtsAZ filaments, the major orchestrators of bacterial cell division, are present uniformly around the leading edge of the invaginating vegetative septa, they are only present on the mother cell side of the invaginating sporulation septa. We provide evidence suggesting that the different distribution and number of FtsAZ filaments impact septal thickness, causing vegetative septa to be thicker than sporulation septa already during constriction. Finally, we show that a sporulation-specific protein, SpoIIE, regulates asymmetric divisome localization and septal thickness during sporulation.
Nanotechnology is an avant-garde field of scientific research that revolutionizes technological advancements in the present world. It is a cutting-edge scientific approach that has undoubtedly a ...plethora of functions in controlling environmental pollutants for the welfare of the ecosystem. However, their unprecedented utilization and hysterical release led to a huge threat to the soil microbiome. Nanoparticles(NPs) hamper physicochemical properties of soil along with microbial metabolic activities within rhizospheric soils.Here in this review shed light on concentric aspects of NP-biosynthesis, types, toxicity mechanisms, accumulation within the ecosystem. However, the accrual of tiny NPs into the soil system has dramatically influenced rhizospheric activities in terms of soil properties and biogeochemical cycles. We have focussed on mechanistic pathways engrossed by microbes to deal with NPs.Also, we have elaborated the fate and behavior of NPs within soils. Besides, a piece of very scarce information on NPs-toxicity towards environment and rhizosphere communities is available. Therefore, the present review highlights ecological perspectives of nanotechnology and solutions to such implications. We have comprehend certain strategies such as avant-garde engineering methods, sustainable procedures for NP synthesis along with vatious regulatory actions to manage NP within environment. Moreover, we have devised risk management sustainable and novel strategies to utilize it in a rationalized and integrated manner. With this background, we can develop a comprehensive plan about NPs with novel insights to understand the resistance and toxicity mechanisms of NPs towards microbes. Henceforth, the orientation towards these issues would enhance the understanding of researchers for proper recommendation and promotion of nanotechnology in an optimized and sustainable manner.
•Nanotechnology is a vital field in present era with huge impact in various sectors.•Excessive utilization of nanoparticles are dilapidating towards environment.•Nanoparticles in soil ecosystem disrupts soil architecture and rhizospheric activities.•Nanoparticle interaction and microbial behavior is of paramount importance in ecosystem.•Ecological concerns are crucial for rationalized use of nanotechnology.
Brassinosteroids (BRs) are group of plant steroidal hormones that modulate developmental processes and also have pivotal role in stress management. Biosynthesis of BRs takes place through established ...early C-6 and late C-6 oxidation pathways and the C-22 hydroxylation pathway triggered by activation of the DWF4 gene that acts on multiple intermediates. BRs are recognized at the cell surface by the receptor kinases, BRI1 and BAK1, which relay signals to the nucleus through a phosphorylation cascade involving phosphorylation of BSU1 protein and proteasomal degradation of BIN2 proteins. Inactivation of BIN2 allows BES1/BZR1 to enter the nucleus and regulate the expression of target genes. In the whole cascade of signal recognition, transduction and regulation of target genes, BRs crosstalk with other phytohormones that play significant roles. In the current era, plants are continuously exposed to abiotic stresses and heavy metal stress is one of the major stresses. The present study reveals the mechanism of these events from biosynthesis, transport and crosstalk through receptor kinases and transcriptional networks under heavy metal stress.
We observed the assembly of a nucleus-like structure in bacteria during viral infection. Using fluorescence microscopy and cryo-electron tomography, we showed that Pseudomonas chlororaphis phage ...201φ2-1 assembled a compartment that separated viral DNA from the cytoplasm. The phage compartment was centered by a bipolar tubulin-based spindle, and it segregated phage and bacterial proteins according to function. Proteins involved in DNA replication and transcription localized inside the compartment, whereas proteins involved in translation and nucleotide synthesis localized outside. Later during infection, viral capsids assembled on the cytoplasmic membrane and moved to the surface of the compartment for DNA packaging. Ultimately, viral particles were released from the compartment and the cell lysed. These results demonstrate that phages have evolved a specialized structure to compartmentalize viral replication.
The study of bacterial cell biology is limited by difficulties in visualizing cellular structures at high spatial resolution within their native milieu. Here, we visualize
sporulation using ...cryo-electron tomography coupled with cryo-focused ion beam milling, allowing the reconstruction of native-state cellular sections at molecular resolution. During sporulation, an asymmetrically-positioned septum generates a larger mother cell and a smaller forespore. Subsequently, the mother cell engulfs the forespore. We show that the septal peptidoglycan is not completely degraded at the onset of engulfment. Instead, the septum is uniformly and only slightly thinned as it curves towards the mother cell. Then, the mother cell membrane migrates around the forespore in tiny finger-like projections, whose formation requires the mother cell SpoIIDMP protein complex. We propose that a limited number of SpoIIDMP complexes tether to and degrade the peptidoglycan ahead of the engulfing membrane, generating an irregular membrane front.
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