Amit Kumar Mishra

Bio: Amit Kumar Mishra is an academic researcher from Texas A&M University. The author has contributed to research in topics: Cultivar & Stomatal conductance. The author has an hindex of 8, co-authored 18 publications receiving 295 citations. Previous affiliations of Amit Kumar Mishra include Banaras Hindu University & Ben-Gurion University of the Negev.

Selection of nitrogen responsive root architectural traits in spinach using machine learning and genetic correlations

Abstract: The efficient acquisition and transport of nutrients by plants largely depend on the root architecture. Due to the absence of complex microbial network interactions and soil heterogeneity in a restricted soilless medium, the architecture of roots is a function of genetics defined by the soilless matrix and exogenously supplied nutrients such as nitrogen (N). The knowledge of root trait combinations that offer the optimal nitrogen use efficiency (NUE) is far from being conclusive. The objective of this study was to define the root trait(s) that best predicts and correlates with vegetative biomass under differed N treatments. We used eight image-derived root architectural traits of 202 diverse spinach lines grown in two N concentrations (high N, HN, and low N, LN) in randomized complete blocks design. Supervised random forest (RF) machine learning augmented by ranger hyperparameter grid search was used to predict the variable importance of the root traits. We also determined the broad-sense heritability (H) and genetic (rg) and phenotypic (rp) correlations between root traits and the vegetative biomass (shoot weight, SWt). Each root trait was assigned a predicted importance rank based on the trait’s contribution to the cumulative reduction in the mean square error (MSE) in the RF tree regression models for SWt. The root traits were further prioritized for potential selection based on the rg and SWt correlated response (CR). The predicted importance of the eight root traits showed that the number of root tips (Tips) and root length (RLength) under HN and crossings (Xsings) and root average diameter (RAvdiam) under LN were the most relevant. SWt had a highly antagonistic rg (− 0.83) to RAvdiam, but a high predicted indirect selection efficiency (− 112.8%) with RAvdiam under LN; RAvdiam showed no significant rg or rp to SWt under HN. In limited N availability, we suggest that selecting against larger RAvdiam as a secondary trait might improve biomass and, hence, NUE with no apparent yield penalty under HN.

Effect of climate change on plant secondary metabolism: An ecological perspective

Abstract: Climate change includes the instantaneous and rapid alteration of numerous important environmental parameters that regulates the dynamics of the ecosystem. This rapid change may cause direct and secondary physiological effects on plants including alteration in plant secondary metabolism. Plant secondary metabolites are generally referred to as compounds that are essential for the plant to interact with its environment and also used for therapeutic purposes. These also play an important role in defense mechanisms, act as important signaling molecules under different environmental stresses, and thus play an important role in the adaptation of plants to extreme environments. Various environmental factors such as temperature, light, ultra-violet B radiation, tropospheric O3, salinity, and soil water content can affect the biosynthesis and accumulation of secondary metabolites in plants. This chapter will summarize the effect of various environmental factors on secondary metabolism and pave a way to acquire important bioactive compounds from plants.

Comparative analyses of genotoxicity, oxidative stress and antioxidative defence system under exposure of methyl parathion and hexaconazole in barley (Hordeum vulgare L.)

Abstract: The present study aims to evaluate the comparative effects of methyl parathion and hexaconazole on genotoxicity, oxidative stress, antioxidative defence system and photosynthetic pigments in barley (Hordeum vulgare L. variety karan-16). The seeds were exposed with three different concentrations, i.e. 0.05, 0.1 and 0.5 % for 6 h after three pre-soaking durations 7, 17 and 27 h which represents G1, S and G2 phases of the cell cycle, respectively. Ethyl methane sulphonate, a well-known mutagenic agent and double distilled water, was used as positive and negative controls, respectively. The results indicate significant decrease in mitotic index with increasing concentrations of pesticides, and the extent was higher in methyl parathion. Chromosomal aberrations were found more frequent in methyl parathion than hexaconazole as compared to their respective controls. Treatment with the pesticides induced oxidative stress which was evident with higher contents of H2O2 and lipid peroxidation, and the increase was more prominent in methyl parathion. Contents of total phenolics were increased; however, soluble protein content showed a reverse trend. Among the enzymatic antioxidants, activities of superoxide dismutase and peroxidase were significantly up-regulated, and more increase was noticed in hexaconazole. Increments in total chlorophyll and carotenoid contents were observed up to 0.1 % but decreased at higher concentration (0.5 %), and the reductions were more prominent in methyl parathion than hexaconazole as compared to their respective controls. Methyl parathion treatment caused more damage in the plant cells of barley as compared to hexaconazole, which may be closely related to higher genotoxicity and oxidative stress.

Rising Atmospheric Carbon Dioxide and Plant Responses: Current and Future Consequences

Abstract: The industrial revolution, population explosion, urbanization, and the use of advanced technological instruments have accelerated the consumption of fossil fuels leading to changes in the gaseous composition of the Earth’s atmosphere. The combustion of fossil fuel acts as a principal source of carbon dioxide (CO2) and is still contributing to its continuous rise in the atmosphere. The levels of CO2 in the atmosphere have significantly increased since the preindustrial era and future projections predict that its concentration will be doubled in the next 50 years, which will cause a significant impact on global weather patterns, including temperature increases by an average of 0.5°C per decade. As per future projections regarding greenhouse gases made by the Intergovernmental Panel on Climate Change, the projected levels of CO2 will range from 500 to 1000 ppm by the end of the 21st century. Currently, crop plants are exposed to CO2 levels that have not been experienced from the time of the preindustrial era, and agriculture is facing a future of uncertain consequences of global climate change. An understanding of the influence of climate change on future crop production requires an appreciation of the general responses of a range of crop types to elevated CO2 contents and the ways in which those affects interact with other factors. Rising CO2 is considered an important aspect of global climate change as it has the potential to enhance crop productivity, which will be required to feed the increasing population across the globe. The objective of this chapter is to present an overview of the responses of plants to high CO2 and the fundamental mechanisms behind those responses.

eMedicine

Abstract: eMedicine创建于1996年，由近万名临床医师作为作者或编辑参与此临床医学知识库的建设，其中编辑均是来自美国哈佛、耶鲁、斯坦福、芝加哥、德克萨斯、加州大学等各分校医学院的教授或副教授。

Antioxidant responses of wheat plants under stress

Abstract: Currently, food security depends on the increased production of cereals such as wheat (Triticum aestivum L.), which is an important source of calories and protein for humans. However, cells of the crop have suffered from the accumulation of reactive oxygen species (ROS), which can cause severe oxidative damage to the plants, due to environmental stresses. ROS are toxic molecules found in various subcellular compartments. The equilibrium between the production and detoxification of ROS is sustained by enzymatic and nonenzymatic antioxidants. In the present review, we offer a brief summary of antioxidant defense and hydrogen peroxide (H2O2) signaling in wheat plants. Wheat plants increase antioxidant defense mechanisms under abiotic stresses, such as drought, cold, heat, salinity and UV-B radiation, to alleviate oxidative damage. Moreover, H2O2 signaling is an important factor contributing to stress tolerance in cereals.

Design and construction

Abstract: This chapter discusses a current comparator. The design of the various components of a comparator may be affected by these factors. To detect short circuit and insulation faults arising during construction and to confirm the effectiveness of the shielding as it is installed, the probe test should be carried out at frequent intervals during the construction.

Response and adaptation of photosynthesis, respiration, and antioxidant systems to elevated CO2 with environmental stress in plants.

Abstract: It is well known that plant photosynthesis and respiration are two fundamental and crucial physiological processes, while the critical role of the antioxidant system in response to abiotic factors is still a focus point for investigating physiological stress. Although one key metabolic process and its response to climatic change have already been reported and reviewed, an integrative review, including several biological processes at multiple scales, has not been well reported. The current review will present a synthesis focusing on the underlying mechanisms in the responses to elevated CO2 at multiple scales, including molecular, cellular, biochemical, physiological, and individual aspects, particularly, for these biological processes under elevated CO2 with other key abiotic stresses, such as heat, drought, and ozone pollution, as well as nitrogen limitation. The present comprehensive review may add timely and substantial information about the topic in recent studies, while it presents what has been well established in previous reviews. First, an outline of the critical biological processes, and an overview of their roles in environmental regulation, is presented. Second, the research advances with regard to the individual subtopics are reviewed, including the response and adaptation of the photosynthetic capacity, respiration, and antioxidant system to CO2 enrichment alone, and its combination with other climatic change factors. Finally, the potential applications for plant responses at various levels to climate change are discussed. The above issue is currently of crucial concern worldwide, and this review may help in a better understanding of how plants deal with elevated CO2 using other mainstream abiotic factors, including molecular, cellular, biochemical, physiological, and whole individual processes, and the better management of the ecological environment, climate change, and sustainable development.

Trends in Seaweed Extract Based Biostimulants: Manufacturing Process and Beneficial Effect on Soil-Plant Systems

Abstract: The time when plant biostimulants were considered as "snake oil" is erstwhile and the skepticism regarding their agricultural benefits has significantly faded, as solid scientific evidences of their positive effects are continuously provided. Currently plant biostimulants are considered as a full-fledged class of agri-inputs and highly attractive business opportunity for major actors of the agroindustry. As the dominant category of the biostimulant segment, seaweed extracts were key in this growing renown. They are widely known as substances with the function of mitigating abiotic stress and enhancing plant productivity. Seaweed extracts are derived from the extraction of several macroalgae species, which depending on the extraction methodology lead to the production of complex mixtures of biologically active compounds. Consequently, plant responses are often inconsistent, and precisely deciphering the involved mechanism of action remains highly intricate. Recently, scientists all over the world have been interested to exploring hidden mechanism of action of these resources through the employment of multidisciplinary and high-throughput approaches, combining plant physiology, molecular biology, agronomy, and multi-omics techniques. The aim of this review is to provide fresh insights into the concept of seaweed extract (SE), through addressing the subject in newfangled standpoints based on current scientific knowledge, and taking into consideration both academic and industrial claims in concomitance with market's requirements. The crucial extraction process as well as the effect of such products on nutrient uptake and their role in abiotic and biotic stress tolerance are scrutinized with emphasizing the involved mechanisms at the metabolic and genetic level. Additionally, some often overlooked and indirect effects of seaweed extracts, such as their influence on plant microbiome are discussed. Finally, the plausible impact of the recently approved plant biostimulant regulation on seaweed extract industry is addressed.