Browsing by Author "Neelwarne, Bhagyalakshmi"

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    Integrating classical and alternative respiratory pathway
    (John Wiley & Sons, 2015) Gupta, Kapuganti Jagadis; Neelwarne, Bhagyalakshmi; Mur, Luis A.J.
    Respiratory pathways are vital for plant carbon and energy metabolism, which is the main use of most assimilated carbohydrates. Most respiratory pathways are very well established, the prominent being glycolysis in cytosol and the tricarboxylic acid (TCA) cycle, which occurs in the matrix of mitochondria coupled with the electron transport chain (ETC) which functions along the inner mitochondrial membrane. This chapter integrates such alternative respiratory pathways with components of the classical oxidative-phosphorylative pathways. Mitochondrial electron transport generates ATP by using the reducing equivalents derived through the operation of the TCA-cycle. Currently most research on alternative electron transfer is focused on nonphosphorylating bypass mechanisms: a second oxidase – the alternative oxidase (AOX), an external NAD (P) H dehydrogenases in the first part of ETC, and also plant uncoupling mitochondrial proteins (PUCPs). Electron transfer flavoprotein (ETF) is an electron acceptor for at least nine mitochondrial matrix flavoprotein dehydrogenases.
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    Polyamine induction in postharvest banana fruits in response to NO donor SNP occurs via L-arginine mediated pathway and not via competitive diversion of S-adenosyl-L-methionine
    (MDPI AG, 2019) Lokesh, Veeresh; Manjunatha, Girigowda; Hegde, Namratha S.; Bulle, Mallesham; Puthusseri, Bijesh; Gupta, Kapuganti Jagadis; Neelwarne, Bhagyalakshmi
    Nitric oxide (NO) is known to antagonize ethylene by various mechanisms; one of such mechanisms is reducing ethylene levels by competitive action on S-adenosyl-L-methionine (SAM)—a common precursor for both ethylene and polyamines (PAs) biosynthesis. In order to investigate whether this mechanism of SAM pool diversion by NO occur towards PAs biosynthesis in banana, we studied the effect of NO on alterations in the levels of PAs, which in turn modulate ethylene levels during ripening. In response to NO donor sodium nitroprusside (SNP) treatment, all three major PAs viz. putrescine, spermidine and spermine were induced in control as well as ethylene pre-treated banana fruits. However, the gene expression studies in two popular banana varieties of diverse genomes, Nanjanagudu rasabale (NR; AAB genome) and Cavendish (CAV; AAA genome) revealed the downregulation of SAM decarboxylase, an intermediate gene involved in ethylene and PA pathway after the fifth day of NO donor SNP treatment, suggesting that ethylene and PA pathways do not compete for SAM. Interestingly, arginine decarboxylase belonging to arginine-mediated route of PA biosynthesis was upregulated several folds in response to the SNP treatment. These observations revealed that NO induces PAs via l-arginine-mediated route and not via diversion of SAM pool.