Browsing by Author "Florez-Sarasa, Igor"

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Does the alternative respiratory pathway offer protection against the adverse effects resulting from climate change?
(Oxford University Press, 2020) Florez-Sarasa, Igor; Fernie, Alisdair R; Gupta, Kapuganti Jagadis
Elevated greenhouse gases (GHG) induce adverse conditions directly and indirectly causing decreases in plant productivity. To deal with climate change effects, plants have developed various mechanisms including the fine-tuning of metabolism. Plant respiratory metabolism is highly flexible due to presence of various alternative pathways. The mitochondrial alternative oxidase (AOX) respiratory pathway is responsive to these changes and several lines of evidence suggest it plays a role in reducing excesses of ROS and RNS while providing metabolic flexibility under stress. Here we discuss the importance of the AOX pathway in dealing with elevated carbon dioxide (CO2), nitrogen oxides (NOx), ozone (O3) and the main abiotic stresses induced by climate change. Recent advances in our understanding concerning the in vivo regulation of AOX and its structural properties suggest that novel AOXs with altered regulatory properties could be used in future gene editing strategies. We suggest that fine-tune modulation of the regulatory properties of AOX and targeting its expression in different plant tissues could improve plant growth and productivity under climate change conditions promoted by elevated GHG. Moreover, we also emphasise the need of extensive study on the interactive effects of major global change factors on AOX respiration and the importance of studies differentiating between the roles of AOX in sink versus source tissues under field conditions in order to improve plant productivity in response to elevated GHG.
Interaction of nitric oxide with the components of plant mitochondrial electron transport chain
(Oxford University Press, 2018) Gupta, Kapuganti Jagadis; Kumari, Aprajita; Florez-Sarasa, Igor; Fernie, Alisdair R; Igamberdiev, Abir U
Mitochondria are not only major sites for energy production but also participate in several alternative functions, among these generation of nitric oxide (NO) and its different impacts on this organelle is increasing attention. The inner mitochondrial membrane contains the chain of protein complexes, and electron transfer via oxidation of various organic acids and reducing equivalents leads to generation of proton gradient that results in energy production. Recent evidence suggests that these complexes are sources and targets for NO. Complex I and rotenone-insensitive NAD(P)H dehydrogenases regulate hypoxic NO production, while complex I also participates in the formation of supercomplex with complex III under hypoxia. Complex II is a target for NO which by inhibiting Fe-S centres regulates ROS generation, and complex III is one of the major sites for NO production and the produced NO participates in the phytoglobin-NO cycle that leads to the maintenance of redox level and limited energy production under hypoxia. Expression of the alternative oxidase (AOX) is induced by NO under various stress conditions, and evidence exists that AOX can regulate mitochondrial NO production. Complex IV is another major site for NO production which can also be linked to ATP generation via the phytoglobin-NO cycle. Inhibition of complex IV by NO can prevent oxygen depletion at the frontier of anoxia. The NO production and action on various complexes play a major role in NO signalling and energy metabolism.