The Cyanide-Resistant Oxidase: To Inhibit or Not to Inhibit, That Is the Question

Day, David A.; Krab, Klass; Lambers, Hans; Moore, Anthony L.; Siedow, James N.; Wagner, Anneke M.; Wiskich, Joseph T.

doi:10.1104/pp.110.1.1

Cited by 129 publications

(77 citation statements)

References 11 publications

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“…Assuming that the entire increase in the respiration rate occurred via the alternative pathway, application of the Stefan-Boltzmann equation (Nobel, 1983) indicates that the total heat that could potentially be produced is two orders of magnitude below that required to account for the 0.5 to 1°C temperature increase observed by Van Der Straeten et al (1995). Further, the reported increase in alternative oxidase activity was demonstrated by the addition of SHAM, which may not represent a true measure of Val, in vivo in the absence of inhibitors (Day et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

“…In recent years it has been demonstrated that the alternative oxidase can compete for electrons with an unsaturated Cyt pathway (Hoefnagel et al, 1995;Siedow and Umbach, 1995), and that the use of inhibitors to quantify the activity of the alternative oxidase is unsound Ribas-Carbo et al, 1995;Day et al, 1996). Currently, the only available method to measure the partitioning of electrons between the alternative and Cyt pathways in the absence of inhibitors is that of O,-isotope fractionation, which can be performed on intact tissue (Robinson et al, 1992 and on isolated mitochondria (Guy et al, 1989;Ribas-Carbo et al, 1995.…”

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confidence: 99%

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The Effects of Salicylic Acid and Tobacco Mosaic Virus Infection on the Alternative Oxidase of Tobacco

et al. 1997

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Salicylic acid (SA) is a signal in systemic acquired resistance and an inducer of the alternative oxidase protein in tobacco (Nicofiana tabacum cv Xanthi nc) cell suspensions and during thermogenesis i n aroid spadices. The effects of SA on the levels of alternative oxidase protein and the pathogenesis-related l a mRNA (a marker for systemic acquired resistance), and on the partitioning of electrons between the Cyt and alternative pathways were investigated in tobacco. Leaves were treated with 1.0 mM SA and mitochondria isolated at times between 1 h and 3 d after treatment. Alternative oxidase protein increased 2.5-fold within 5 h, reached a maximum (9-fold) after 12 h, and remained at twice the level of control plants after 3 d. Measurements of isotope fractionation of '*O by intact leaf tissue gave a value of 23% at all times, identical to that of control plants, indicating a constant 27 to 30% of electron-flow partitioning to the alternative oxidase independent of treatment with SA. Transgenic NahC tobacco p!ants that express bacterial salicylate hydroxylase and possess very low levels of SA gave a fractionation of 23% and showed control levels of alternative oxidase protein, suggesting that steady-state alternative oxidase accumulates i n an SA-independent manner. lnfection of plants with tobacco mosaic virus resulted in an increase in alternative oxidase protein in both infected and systemic leaves, but no increase was observed in comparably infected NahC plants. Total respiration rate and partitioning of electrons to the alternative pathway in virus-infected plants was comparable to that in uninfected controls.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

The Effects of Salicylic Acid and Tobacco Mosaic Virus Infection on the Alternative Oxidase of Tobacco

et al. 1997

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“…SHAM, an inhibitor of AOX, and KCN, an inhibitor of the cytochrome pathway). However, the use of inhibitors has now been discredited (Atkin et al, 1995 ;Day et al, 1996). Consequently, all previous work assessing the effect of temperature on AOX with the use of respiratory inhibitors must be treated with caution.…”

Section:   Q "!     mentioning

confidence: 99%

Response of root respiration to changes in temperature and its relevance to global warming

2000

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Global warming over the next century is likely to be associated with a change in the extent to which atmospheric and soil temperatures fluctuate, on both a daily and a seasonal basis. The average annual temperature of the Earth's surface is expected to increase, as is the frequency of hot days. In this review, we explore what effects short-term and long-term changes in temperature are likely to have on root respiratory metabolism, and what impacts such changes will have on daily, seasonal and annual CO # release by roots under field conditions. We demonstrate that Q "! values, and the degree of acclimation, differ between and within plant species. Changes in the temperature sensitivity of respiration with measuring temperature are highlighted. Temperature-dependent changes in adenylate control and substrate supply are likely to control the Q "! and degree of acclimation of root respiration. Limitations in respiration capacity are unlikely to control respiratory flux at most temperatures. The potential role of nonphosphorylating pathways such as the alternative oxidase in controlling Q "! values is highlighted. The possibility that potentially rapid changes in adenylate control might underlie the acclimation response (rather than slow changes in enzyme capacity) has implications for the total amount of CO # respired by roots daily and annually. Our modelling suggests that rapid acclimation will result in near-perfect homeostasis of respiration rates and minimize annual CO # release. However, annual CO # release increases substantially if the speed of full acclimation is lower. Our modelling exercise also shows that high Q "! values have the potential to increase daily and annual CO # release substantially, particularly if the frequency of hot days increases after global warming.

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“…Thus, in 7-to 8-d-old cluster roots, the increased expression of AOX presumably reflects an increased in vivo activity that facilitates carboxylate synthesis and/or restricted cyt pathway activity, recycling NADH. However, further studies using the O 2 -fractionation technique (Guy et al, 1992;Day et al, 1996) are required to determine the AOX activity of intact cluster-roots.…”

Section: The Role Of Aoxmentioning

confidence: 99%

Developmental Physiology of Cluster-Root Carboxylate Synthesis and Exudation in Harsh Hakea. Expression of Phosphoenolpyruvate Carboxylase and the Alternative Oxidase

Shane¹,

Cramer²,

et al. 2004

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Harsh hakea (Hakea prostrata R.Br.) is a member of the Proteaceae family, which is highly represented on the extremely nutrientimpoverished soils in southwest Australia. When phosphorus is limiting, harsh hakea develops proteoid or cluster roots that release carboxylates that mobilize sparingly soluble phosphate in the rhizosphere. To investigate the physiology underlying the synthesis and exudation of carboxylates from cluster roots in Proteaceae, we measured O 2 consumption, CO 2 release, internal carboxylate concentrations and carboxylate exudation, and the abundance of the enzymes phosphoenolpyruvate carboxylase and alternative oxidase (AOX) over a 3-week time course of cluster-root development. Peak rates of citrate and malate exudation were observed from 12-to 13-d-old cluster roots, preceded by a reduction in cluster-root total protein levels and a reduced rate of O 2 consumption. In harsh hakea, phosphoenolpyruvate carboxylase expression was relatively constant in cluster roots, regardless of developmental stage. During cluster-root maturation, however, the expression of AOX protein increased prior to the time when citrate and malate exudation peaked. This increase in AOX protein levels is presumably needed to allow a greater flow of electrons through the mitochondrial electron transport chain in the absence of rapid ATP turnover. Citrate and isocitrate synthesis and accumulation contributed in a major way to the subsequent burst of citrate and malate exudation. Phosphorus accumulated by harsh hakea cluster roots was remobilized during senescence as part of their efficient P cycling strategy for growth on nutrient impoverished soils.In some plant species, a shortage of phosphorus induces the development of dense clusters of determinate branch roots (rootlets) that arise, en masse, from a localized region of the parent root axis. These short-lived structures have been termed proteoid roots because they were first described for Proteaceae (Purnell, 1960) but have since been found in a wide range of other species and families and are now often referred to as cluster roots . Most of our advances in cluster-root biology have been derived from studies of the crop species Lupinus albus (Fabaceae family) (Gardner et al

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The Cyanide-Resistant Oxidase: To Inhibit or Not to Inhibit, That Is the Question

Cited by 129 publications

References 11 publications

The Effects of Salicylic Acid and Tobacco Mosaic Virus Infection on the Alternative Oxidase of Tobacco

The Effects of Salicylic Acid and Tobacco Mosaic Virus Infection on the Alternative Oxidase of Tobacco

Response of root respiration to changes in temperature and its relevance to global warming

Developmental Physiology of Cluster-Root Carboxylate Synthesis and Exudation in Harsh Hakea. Expression of Phosphoenolpyruvate Carboxylase and the Alternative Oxidase

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