Publications of NIPGR Scientists

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Author: search.filters.author.Gupta, Alok KumarSubject: search.filters.subject.Nitric oxide

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    Moving nitrogen to the centre of plant defence against pathogens
    (Oxford University Press, 2017) Mur, Luis A.J.; Simpson, Catherine; Kumari, Aprajita; Gupta, Alok Kumar; Gupta, Kapuganti Jagadis
    Background Plants require nitrogen (N) for growth, development and defence against abiotic and biotic stresses. The extensive use of artificial N fertilizers has played an important role in the Green Revolution. N assimilation can involve a reductase series (NO–3→ NO–2 → NH+4) followed by transamination to form amino acids. Given its widespread use, the agricultural impact of N nutrition on disease development has been extensively examined. Scope: When a pathogen first comes into contact with a host, it is usually nutrient starved such that rapid assimilation of host nutrients is essential for successful pathogenesis. Equally, the host may reallocate its nutrients to defence responses or away from the site of attempted infection. Exogenous application of N fertilizer can, therefore, shift the balance in favour of the host or pathogen. In line with this, increasing N has been reported either to increase or to decrease plant resistance to pathogens, which reflects differences in the infection strategies of discrete pathogens. Beyond considering only N content, the use of NO-3 or NH+4 fertilizers affects the outcome of plant–pathogen interactions. NO-3 feeding augments hypersensitive response- (HR) mediated resistance, while ammonium nutrition can compromise defence. Metabolically, NO–3 enhances production of polyamines such as spermine and spermidine, which are established defence signals, with NH+4 nutrition leading to increased γ-aminobutyric acid (GABA) levels which may be a nutrient source for the pathogen. Within the defensive N economy, the roles of nitric oxide must also be considered. This is mostly generated from NO–2 by nitrate reductase and is elicited by both pathogen-associated microbial patterns and gene-for-gene-mediated defences. Nitric oxide (NO) production and associated defences are therefore NO-3 dependent and are compromised by NH+4. Conclusion:This review demonstrates how N content and form plays an essential role in defensive primary and secondary metabolism and NO-mediated events.
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    Chemiluminescence detection of nitric oxide from roots, leaves, and root mitochondria
    (Springer, 2016) Wany, Aakanksha; Gupta, Alok Kumar; Kumari, Aprajita; Gupta, Shika; Mishra, Sonal; Jaintu, Ritika; Pathak, Pradeep K.; Gupta, Kapuganti Jagadis
    NO is a free radical with short half-life and high reactivity; due to its physiochemical properties it is very difficult to detect the concentrations precisely. Chemiluminescence is one of the robust methods to quantify NO. Detection of NO by this method is based on reaction of nitric oxide with ozone which leads to emission of light and amount of light is proportional to NO. By this method NO can be measured in the range of pico moles to nano moles range. Using direct chemiluminescence method, NO emitted into the gas stream can be detected whereas using indirect chemiluminescence oxidized forms of NO can also be detected. We detected NO using purified nitrate reductase, mitochondria, cell suspensions, and roots; detail measurement method is described here.
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    The functional role of nitric oxide in plant mitochondrial metabolism
    (Elsevier B.V., 2016) Gupta, Alok Kumar; Kumari, Aprajita; Mishra, Sonal; Wany, Aakanksha; Gupta, Kapuganti Jagadis
    In recent years, mitochondrial nitric oxide (NO) production has attracted increasing attention. Mitochondria generate NO using nitrite as a substrate. Cytochrome c oxidase and other components of the electron transport chain also contribute to NO generation. Accumulating evidence indicates that mitochondria are scavengers of NO. Furthermore, several genes encoding mitochondrial proteins, as well as mitochondrial proteins, are regulated by NO. In this chapter, we provided an overview of the mechanisms of NO generation and scavenging in mitochondria and of the NO-dependent regulation of proteins and genes encoding mitochondrial proteins. In addition, the functional roles of NO in mitochondrial metabolism, such as inhibition of aconitase, production of ATP and induction of alternative oxidase are presented.