The role of nitrite and nitric oxide under low oxygen conditions in plants

Abstract

Plant tissues, particularly roots, can be subjected to periods of hypoxia due to environmental circumstances. Plants have developed various adaptations in response to hypoxic stress and these have been extensively described. Less wellappreciated is the body of evidence demonstrating that scavenging of nitric oxide (NO) and the reduction of nitrate/nitrite regulate important mechanisms that contribute to tolerance to hypoxia. Whilst ethylene controls hyponasty and aerenchyma formation, NO production apparently regulates hypoxic ethylene biosynthesis. In the hypoxic mitochondrion, cytochrome c oxidase, which is a major source of NO, is also inhibited by NO, thereby reducing the respiratory rate and enhancing local oxygen concentrations. Nitrite can maintain ATP generation under hypoxia by coupling its reduction to the translocation of protons from the inner side of mitochondria and generating an electrochemical gradient. This reaction can be further coupled to a reaction whereby non-symbiotic haemoglobin oxidizes NO to nitrate. In addition to these functions, nitrite has been reported to influence mitochondrial structure and supercomplex formation, as well as playing a role in oxygen sensing via the N-end rule pathway. These studies establish that nitrite and NO perform multiple functions during plant hypoxia and suggest that further research into the underlying mechanisms is warranted.

Nitrous Oxide Emissions from Paddies: Understanding the Role of Rice Plants

“…Oxygen deprivation affects the plant mitochondria [67,68]. Nitrate and nitrite are shown to have a protective effect on mitochondria under oxygen deprivation [68].…”

“…Oxygen deprivation affects the plant mitochondria [67,68]. Nitrate and nitrite are shown to have a protective effect on mitochondria under oxygen deprivation [68]. Hypoxia strongly decreases the NO 2 reduction to NH 4 and the NH 4 assimilation to amino acids [35].…”

Rola etylenu i zmiany na poziomie transkryptomu w odpowiedzi na stres niedotlenienia u roślin

“…Oznacza to, że w warunkach beztlenowych, uwzględniając produkty glikolizy, końcowa ilość ATP zwiększa się do czterech cząsteczek. Dlatego można uznać ten szlak za równie istotny w odpowiedzi na hipoksję, co szlaki fermentacyjne [36,37].…”

“…nitrate reductase 2), produkcji NO a następnie syntezy fitoglobiny klasy 1 (PGB1, ang. phytoglobin1) [37]. Roślinne niesymbiotyczne hemoglobiny uznawane są za jeden ze znanych sensorów niedotlenienia i biorą udział w rozkładzie NO.…”

“…Cykl fitoglobina-tlenek azotu związany jest z utlenianiem NADH i utrzymaniem odpowiedniego poziomu ATP w warunkach niedotlenienia. Polega na usuwaniu NO przez oksyfitoglobinę (Pgb(Fe 2+ )O 2 ), a następnie na jej regeneracji przez białko reduktazy metfitoglobiny (MetPgb-R) [37]. Wytwarzanie NO w warunkach hipoksji prowadzi także do aktywacji genów kodujących syntazę ACC (ang.…”