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Author

Amit Kumar Mishra

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

Papers
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Journal ArticleDOI
Abstract: In past few years, atmospheric concentrations of carbon dioxide (CO2) and tropospheric ozone (O3) have increased due to anthropogenic activities. CO2 enhances the plant growth and surface level of O3 is a well-known phyto-toxic pollutant. Present study was conducted to assess the impact of elevated levels of CO2 and O3, singly and in combination on two wheat cultivars HUW-37 and K-9107 on their growth, yield attributes and grain quality in open top chambers (OTCs). Wheat plants under elevated CO2 (EC) showed increment in growth parameters while exposure to elevated O3 (EO) showed an opposite trend than EC. In elevated CO2 + O3 (ECO) exposure, elevated CO2 fully protected wheat cultivars against negative effects of O3. Yield parameters showed significant increase in EC followed by ECO and in EO, significant reductions in yield were noticed in both the cultivars. Protein and total free amino-acids decreased in grains of EC, ECO and EO in both the test cultivars. Total soluble sugars and starch contents in grains increased due to EC and ECO and decreased in EO, however reducing sugars showed an opposite trend in both the cultivars. The yield data obtained from the experiment showed cultivar specific response as cultivar HUW-37 proved to be sensitive as compared to K-9107 against ambient and elevated levels of O3. The study also concludes that elevated CO2 nullified the negative impact of elevated O3 in both the test cultivars of wheat.

57 citations

Journal ArticleDOI
TL;DR: Path analysis approach showed that leaf area, plant biomass, stomatal conductance, net assimilation rate, and absolute growth rate were the most important variables influencing yield under O3 stress.
Abstract: Tropospheric ozone (O3) is a well-known threat to global agricultural production. Wheat (Triticum aestivum L.) is the second most important staple crop in India, although little is known about intra-specific variability of Indian wheat cultivars in terms of their sensitivity against O3. In this study, 14 wheat cultivars widely grown in India were exposed to 30 ppb elevated O3 above ambient level using open top chambers to evaluate their response against O3 stress. Different growth and physiological parameters, foliar injury and grain yield were evaluated to assess the sensitivity of cultivars and classified them on the basis of their cumulative stress response index (CSRI). Due to elevated O3, growth parameters, plant biomass, and photosynthetic rates were negatively affected, whereas variable reductions in yield were observed among the test cultivars. Based on CSRI values, HD 2987, DBW 50, DBW 77, and PBW 550 were classified as O3 sensitive; HD 2967, NIAW 34, HD 3059, PBW 502, HUW 213, and HUW 251 as intermediately sensitive, while HUW12, KUNDAN, HUW 55, and KHARCHIYA 65 were found to be O3-tolerant cultivars. Cultivars released after year 2000 were found to be more sensitive compared to earlier released cultivars. Path analysis approach showed that leaf area, plant biomass, stomatal conductance, net assimilation rate, and absolute growth rate were the most important variables influencing yield under O3 stress. Findings of the current study highlight the importance of assessing differential sensitivity and tolerance of wheat cultivars and response of different traits in developing resistance against elevated O3.

44 citations

Journal Article
TL;DR: Under elevated CO2 + O3, elevated levels of CO2 modified the plant performance against O3 in both the cultivars and cultivar HUW-37 was more sensitive to elevated O3 than K-9107.
Abstract: The effects of elevated CO2 and O3, singly and in combination were investigated on various physiological, biochemical and yield parameters of two locally grown wheat (Triticum aestivum L.) cultivars (HUW-37 and K-9107) in open top chambers (OTCs). Elevated CO2 stimulated photosynthetic rate (Ps) and Fv/Fm ratio and reduced the stomatal conductance (gs). Reactive oxygen species, lipid peroxidation, anti-oxidative enzymes, ascorbic acid and total phenolics were higher, whereas Ps, gs, Fv/Fm, protein and photosynthetic pigments were reduced in elevated O3 exposure, as compared to their controls. Under elevated CO2 + O3, elevated levels of CO2 modified the plant performance against O3 in both the cultivars. Elevated CO2 caused significant increase in economic yield. Exposure to elevated O3 caused significant reduction in yield and the effect was cultivar-specific. The study concluded that elevated CO2 ameliorated the negative impact of elevated O3 and cultivar HUW-37 was more sensitive to elevated O3 than K-9107.

44 citations

Journal ArticleDOI
TL;DR: AtPUB46 and AtPUB48 encode plant U-Box E3s and are involved in the response to water stress, and the data suggest that despite encoding highly homologous proteins, AtPUBs biological activity does not fully overlap.
Abstract: Plants respond to abiotic stress on physiological, biochemical and molecular levels. This includes a global change in their cellular proteome achieved by changes in the pattern of their protein synthesis and degradation. The ubiquitin-proteasome system (UPS) is a key player in protein degradation in eukaryotes. Proteins are marked for degradation by the proteasome by coupling short chains of ubiquitin polypeptides in a three-step pathway. The last and regulatory stage is catalyzed by a member of a large family of substrate-specific ubiquitin ligases. We have identified AtPUB46 and AtPUB48—two paralogous genes that encode ubiquitin ligases (E3s)—to have a role in the plant environmental response. The AtPUB46, −47, and −48 appear as tandem gene copies on chromosome 5, and we present a phylogenetic analysis that traces their evolution from an ancestral PUB-ARM gene. Single homozygous T-DNA insertion mutants of AtPUB46 and AtPUB48 displayed hypersensitivity to water stress; this was not observed for similar mutants of AtPUB47. Although the three genes show a similar spatial expression pattern, the steady state levels of their transcripts are differentially affected by abiotic stresses and plant hormones. AtPUB46 and AtPUB48 encode plant U-Box E3s and are involved in the response to water stress. Our data suggest that despite encoding highly homologous proteins, AtPUB46 and AtPUB48 biological activity does not fully overlap.

30 citations

Journal ArticleDOI
TL;DR: Results suggested that higher accumulation of ROS and limited induction of antioxidant defense system led to more leaf injury and impairment of photosynthesis in HUM-2 than HUM-6 depicting its higher sensitivity towards elevated O3.
Abstract: Surface-level ozone (O3) has been regarded as one of the most significant phytotoxic pollutants worldwide. Investigations addressing adverse impacts of elevated O3 on mung bean (Vigna radiata L.), an important leguminous crop of the Indian subcontinent, are still limited. The present study analyzed the differences on the foliar injury, reactive oxygen species (ROS) generation, antioxidative defense system, physiology, and foliar protein profile of two tropical mung bean cultivars (HUM-2 and HUM-6) exposed to elevated O3 under near-natural conditions. Both cultivars were negatively affected by the pollutant, but the response was cultivar-specific. Results revealed that elevated O3 induced higher levels of ROS (O2 ·− and H2O2) and lipid peroxidation leading to greater foliar injury in HUM-2 compared to HUM-6. Photosynthetic pigments, photosynthetic rate, stomatal conductance, and photochemical efficiency reduced under elevated O3 exposure and the extent of reduction was higher in HUM-2. Principal component analysis revealed that photosynthetic performance and quantum yield were drastically affected in HUM-2 as compared to HUM-6. Activities of antioxidative enzymes were also stimulated, suggesting generation of oxidative stress under elevated O3. HUM-6 showed higher induction of antioxidative enzymes than HUM-2. One-dimensional gel electrophoresis analysis showed drastic reductions in the abundantly present ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) large and small subunits and the decrease was higher in HUM-2. Altogether, results suggested that higher accumulation of ROS and limited induction of antioxidant defense system led to more leaf injury and impairment of photosynthesis in HUM-2 than HUM-6 depicting its higher sensitivity towards elevated O3.

27 citations


Cited by
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01 Feb 2009
TL;DR: 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校医学知识库。
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。

1,459 citations

Journal ArticleDOI
TL;DR: A brief summary of antioxidant defense and hydrogen peroxide (H2O2) signaling in wheat plants is offered to alleviate oxidative damage and is an important factor contributing to stress tolerance in cereals.
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.

189 citations

Book ChapterDOI
01 Apr 1972
TL;DR: 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.
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.

184 citations

Journal ArticleDOI
TL;DR: A comprehensive review 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 is presented.
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.

134 citations

Journal ArticleDOI
TL;DR: Variations in soil moisture and nutrient availability, ambient temperature, and atmospheric composition were all shown to affect starch functionality and Genotypic variation appears to be a primary contributor for the response of cereal starches to environmental stress.
Abstract: Stressful environments can alter starch biosynthesis in cereal endosperm. The aim of this review is to carefully examine how starch functional properties are altered when plants encounter environmental parameters outside of the normal range. This is important because while growers and processors require grain yield stability and product uniformity this will be challenging in an era of variable weather patterns. Being able to predict the general physico-chemical nature of the starch as a result of growth status is a step towards the precise agriculture required for the 21st century. Variations in soil moisture and nutrient availability, ambient temperature, and atmospheric composition were all shown to affect starch functionality. Elevated temperature led to the most significant changes in both tropical and temperate cereals and amylose content was the most sensitive parameter under various environmental conditions. Genotypic variation appears to be a primary contributor for the response of cereal starches to environmental stress. Nonetheless, while a large amount of data from single controlled environmental stress experiment is currently available, comparably little is known about whether similar results would be achieved in multifactorial and large-scale settings. The challenges in terms of the need for more detailed experimental descriptions to lessen the study-to-study discrepancies of data and to enhance their interpretability were also discussed. © 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.

100 citations