Rohit Kumar Mishra

Reactive Oxygen Species (ROS): Beneficial Companions of Plants’ Developmental Processes

Reactive oxygen species (ROS) are generated inevitably in the redox reactions of plants, including respiration and photosynthesis. In earlier studies, ROS were considered as toxic by-products of aerobic pathways of the metabolism. But in recent years, concept about ROS has changed because they also participate in developmental processes of plants by acting as signaling molecules. In plants, ROS regulate many developmental processes such as cell proliferation and differentiation, programmed cell death, seed germination, gravitropism, root hair growth and pollen tube development, senescence, etc. Despite much progress, a comprehensive update of advances in the understanding of the mechanisms evoked by ROS that mediate in cell proliferation and development are fragmentry and the matter of ROS perception and the signaling cascade remains open. Therefore, keeping in view the above facts, an attempt has been made in this article to summarize the recent findings regarding updates made in the regulatory action of ROS at various plant developmental stages, which are still not well-known.

Reactive oxygen species signaling and stomatal movement: Current updates and future perspectives

Reactive oxygen species (ROS), a by-product of aerobic metabolism were initially studied in context to their damaging effect but recent decades witnessed significant advancements in understanding the role of ROS as signaling molecules. Contrary to earlier views, it is becoming evident that ROS production is not necessarily a symptom of cellular dysfunction but it might represent a necessary signal in adjusting the cellular machinery according to the altered conditions. Stomatal movement is controlled by multifaceted signaling network in response to endogenous and environmental signals. Furthermore, the stomatal aperture is regulated by a coordinated action of signaling proteins, ROS-generating enzymes, and downstream executors like transporters, ion pumps, plasma membrane channels, which control the turgor pressure of the guard cell. The earliest hallmarks of stomatal closure are ROS accumulation in the apoplast and chloroplasts and thereafter, there is a successive increase in cytoplasmic Ca2+ level which rules the multiple kinases activity that in turn regulates the activity of ROS-generating enzymes and various ion channels. In addition, ROS also regulate the action of multiple proteins directly by oxidative post translational modifications to adjust guard cell signaling. Notwithstanding, an active progress has been made with ROS signaling mechanism but the regulatory action for ROS signaling processes in stomatal movement is still fragmentary. Therefore, keeping in view the above facts, in this mini review the basic concepts and role of ROS signaling in the stomatal movement have been presented comprehensively along with recent highlights.

Management of Cosmetic Embarrassment Caused by Malassezia spp. with Fruticose Lichen Cladia Using Phylogenetic Approach

During anti-Malassezia screening of plants by CLSI broth microdilution method, Cladia aggregata (Swartz) Nyl. (family Cladoniaceae), a fruticose lichen from Sikkim (northeast Himalayan region), has been found effective at minimum inhibitory concentrations (mg/mL) of 2.72, 0.63, and 1.28 against yeast-like fungi namely, M. furfur, M. globosa and M. sympodialis, respectively. These test pathogens are responsible for pityriasis versicolor (PV) and seborrheic dermatitis (SD) in humans. We tried to establish the reason for variable MICs against various Malassezia spp. using bioinformatical tools, thereby reducing the cost of the experimentation. This is the first report on anti-Malassezia activity of C. aggregata and thus can serve as a potential source for the development of cosmaceuticals.

Studies on antidermatophytic activity of waste leaves of Curcuma longa L.

During antidermatophytic screening of some essential oils, Curcuma longa L. exhibited the strongest antifungal activity, completely inhibiting the mycelial growth of ringworm, caused by the fungi- Microsporum gypseum and Trichophyton mentagrophytes. The essential oil from leaves of Curcuma longa was fungicidal at 2.5 μl/ml at which it tolerated heavy doses of inoculum. The fungicidal activity of the oil was thermostable up to 80 °C and self life up to 24 months in storage. The oil also showed a broad fungitoxic spectrum, inhibiting the mycelial growth of other fungi, viz., Epidermophyton floccosum, M. nanum, T. rubrum, T. violaceum. Moreover, up to 5 % concentration it did not exhibit any adverse effect on mammalian skins. The oil has been formulated in the form of an ointment, 1 % w/v and subjected to topical testing on patients of the Out Patient Department (OPD) at Moti Lal Nehru Medical College, Allahabad. Patients were selected on the basis of KOHpositive results and diagnosed tenia corporis. After the second week of treatment, all patients were KOH- negative. At the end of medication, 75 % of patients recovered completely while 15 % showed significant improvement from the disease. The ointment thus, can be exploited commercially after ongoing successful clinical trials. Relationship of the dermatophytes to the toxicity of the oil vis-a-vis phylogeny using molecular data of the pathogens have also been discussed.

Prediction and validation of gold nanoparticles (GNPs) on plant growth promoting rhizobacteria (PGPR): a step toward development of nano-biofertilizers

Abstract Several soil microbes are present in the rhizosphere zone, especially plant growth promoting rhizobacteria (PGPR), which are best known for their plant growth promoting activities. The present study reflects the effect of gold nanoparticles (GNPs) at various concentrations on the growth of PGPR. GNPs were synthesized chemically, by reduction of HAuCl4, and further characterized by UV-Vis spectroscopy, X-ray diffraction technique (XRD), and transmission electron microscopy (TEM), etc. The impact of GNPs on PGPR was investigated by Clinical Laboratory Standards Institute (CLSI) recommended Broth-Microdilution technique against four selected PGPR viz., Pseudomonas fluorescens, Bacillus subtilis, Paenibacillus elgii, and Pseudomonas putida. Neither accelerating nor reducing impact was observed in P. putida due to GNPs. On the contrary, significant increase was observed in the case of P. fluorescens, P. elgii, and B. subtilis, and hence, GNPs can be exploited as nano-biofertilizers.

Current Trends of Engineered Nanoparticles (ENPs) in Sustainable Agriculture: An Overview

Nanotechnology is an interesting area of multifaceted research in agricultural perspective. This technology incorporates the manufacturing of material at nano level. Nanoparticles (NPs) have now become an integral part of research because of their unique features like their size, shape and surface reactivity. In agriculture sector engineered nanoparticles (ENPs) i.e., metal NPs, metal oxide NPs and Carbon Nano Tubes (CNTs) etc has been used in the form of nanofertilizers and nanopesticide/ herbicides. Therefore, the appropriate use of nanoparticles could provide a proficient sustainable platform to achieve the food requirement of global massive population. As of the application of nanotechnology to agriculture and food industry is outturn in enhanced crop yield with better food quality as well as safety. Inspite of the significances of nano-material, negative outcomes should also be taken in consideration before applying it on a large scale.

Detoxification and Tolerance of Heavy Metals in Plants

Abstract Plant growth and metabolisms are regulated by some heavy metals found in Earths crust because they are active constituents of various enzymes. However, their increased concentration may lead to different toxic effects, inhibiting plant growth and development. There are some plants that are capable of surviving in the presence of heavy metals, apparently by adapting the mechanism that involved in common homeostasis as well as removal of metal ions. Plants have diverse mechanisms for metal detoxification, enabling them to tolerate heavy metal stress. The defense systems against heavy metal stress include mycorrhizae, cellular exudates, plasma membrane, heat shock proteins, phytochelatins (PCs), metallothioneins (MTs), organic acids, and amino acids. All the mechanism involved the tolerance of heavy metal concentration at cellular level to avoid the negative impacts. Extracellular plants include roles for mycorrhizae and extracellular exudates in the plasma membrane either by dropping by absorption of heavy metal or by inducing the efflux pumping of metal ions. On the other hand, intracellularly heat shock proteins, MTs, organic acids, amino acids, and PCs also play a vital role in tolerance of different heavy metals. Few metal transporters have been identified in the past few years that actively participate in tolerance of metal specificity. Enhanced application of molecular genetics has shown their eminent contribution in understanding the mechanism of heavy metal tolerance in plants.

A comparative analysis of in vitro growth inhibition of waterborne bacteria with bioactive plant Lippia nodiflora L. and camphor

AbstractIn the current scenario, due to global deterioration of the environment and climate change, among them water pollution possesses serious threat to most of the populace. Waterborne pathogenic bacteria like Escherichia coli, Vibrio cholerae, Salmonella typhimurium, Klebsiella pneumoniae, etc. are responsible for several diseases such as diarrhoea, cholera, salmonellosis, etc. In order to overcome these waterborne bacterial diseases and for purification of water, plants have been of great use for their potential role from very ancient times. The present study deals with the Clinical & Laboratory Standards Institute (CLSI)-recommended broth microdilution antibacterial susceptibility assay of waterborne bacterial pathogens against Lippia nodiflora L. petroleum ether (LNPE) and ethanolic extracts (LNEE) prepared from the leaves and flowers together of Lippia nodiflora (Verbenaceae), in comparison to camphor. Growth inhibition of tested bacterial pathogens was recorded in from of IC50 and MIC values were...

PSII photochemistry, oxidative damage and anti-oxidative enzymes in arsenate-stressed Oryza sativa L. seedlings

ABSTRACT The aim of the present study was to quantify the arsenic-induced damage in rice seedlings in terms of certain physiological and biochemical parameters. For this, hydroponically grown Oryza sativa L. seedlings were exposed to certain doses of AsV as Na2HAsO4 (10, 25, 50 and 100 µM). All the tested doses manifested in a significant loss in the pigments content and photosynthesis, which culminated in retarded growth of the seedlings. The AsV-mediated decline in PSII photochemistry could be correlated with the decline in ϕP0, ψ0, ϕE0 and PIABS. In vitro and in vivo detection of and H2O2 and the consequent rise in malondialdehyde equivalents after AsV treatments stimulated the anti-oxidant enzymes, that is, superoxide dismutase (SOD) (except at 50 and 100 µM AsV), peroxidase and catalase, activity which was further confirmed by the native polyacrylamide gel electrophoresis (PAGE) that also revealed the least expression of SOD isoforms against 50 and 100 µM AsV treatment. The present investigation is a categorical demonstration of the inhibitory behaviour of AsV in O. sativa L. seedlings. At lower doses of arsenate, reactive oxygen species and anti-oxidants cooperatively acted in such a way that the impacts of the stress were far lesser on various growth and physiological parameters.

Environmental impact of leaching of trace elements from fly ash dumps on aquatic ecosystems

ABSTRACT Ten sampling points were selected in Kanhan River, situated near the ash dump sites of Koradi Thermal Power Plant, Nagpur. The leaching of trace elements from fly ash dumps was experimentally determined by acid digestion, batch leaching and toxicity characteristic leaching procedure tests. Elemental concentrations in river water, sediment, plankton and five commonly prevailing fish species (Catla catla, Labeo bata, Cyprinus carpio, Cirrhinus reba, Puntius ticto) were determined using a Flame Atomic Absorption Spectrophotometer during the pre-monsoon and post-monsoon seasons. Metal concentrations (Cr, Mn, Zn, Cu, Fe, Ni, Cu and Pb) in river water were higher during the pre-monsoon season compared to the post-monsoon season. Zn (30.65 mg/kg) was observed to be the most predominant metal in plankton during the pre-monsoon season while, during the post-monsoon season, Fe (21.19 mg/kg) showed the maximum concentration. Muscles of C. catla had metal concentrations (Cr, Mn, Zn, Fe, Cu and Pb) above the permissible limits of Food and Agricultural Organization (FAO 1983) during the pre-monsoon season. Bioaccumulation factor (BAF) was found highest for Cr (37.5) in muscles of C. catla during the pre-monsoon season, while BAF was observed to be maximum in L. bata for Cu (28.09), which may be detrimental for human consumption.