The Cyanide-Resistant Pathway of Plant Mitochondria

Lance, C.; Chauveau, Michèle; Dizengremel, Pierre

doi:10.1007/978-3-642-70101-6_9

Cited by 98 publications

(78 citation statements)

References 139 publications

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“…Knowledge about respiratory metabolism during saline stress conditions is still lacking. In this context, the role of the nonphosphorylating cyanide-resistant pathway, which is a common feature of higher plant respiration (18,28), is not fully elucidated. Some reports show that the activity ofthis alternative pathway could be modified in stress situations (17,25 …”

Section: Plant Materialsmentioning

confidence: 99%

Changes in Properties of Barley Leaf Mitochondria Isolated from NaCl-Treated Plants

Jolivet¹,

Pireaux²,

Dizengremel³

1990

Plant Physiol.

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Treatment of barley (Hordeum vulgare) seedlings with 400 millimolar NaCI for 3 days resulted in a reduction in plant growth and an increase in the leaf content in ions (K+ + Na ) and proline. Purified mitochondria were successfully isolated from barley leaves. Good oxidative and phosphorylative properties were observed with malate as substrate. Malate-dependent electron transport was found to be only partly inhibited by cyanide, the remaining oxygen uptake being SHAM sensitive. The properties of mitochondria from NaCI-treated barley were modified. The efficiency of phosphorylation was diminished with only a slight decrease in the oxidation rates. In both isolated mitochondria and whole leaf tissue of treated plants, the lower respiration rate was due to a lower cytochrome pathway activity. In mitochondria, the activity of the alternative pathway was not modified by salt treatment, whereas this activity was increased in whole leaf tissue. The possible participation of the altemative pathway in response to salt stress will be discussed.Among crop plants, barley seems to be rather resistant to deleterious effects of NaCI salinity. However, under conditions of high saline environment barley plants do show growth reduction. In this context, changes in ion uptake (2), proline levels (33), gene expression (24), or more recently, changes in metabolic rates in roots (8) have been investigated. However, no work has been done on the role of mitochondria in leaves of barley plants submitted to high NaCl stress.The isolation and purification of green leaf mitochondria from barley was performed, and the oxidative and phosphorylative properties of these mitochondria were compared between control plant and the treated with 400 mM NaCl. The effects of salt on cyanide resistance were also investigated in both isolated mitochondria and whole leaf tissue to look for a role of the alternative pathway in salt-treated barley leaves. Uptake and compartmentation of ions in whole plant organs require energy mainly in the form of ATP generated from respiration (32). The production of compatible solutes is linked not only to the supply of reducing power and carbon skeletons, but also to energy production which depends on the efficiency of the phosphorylation process. Knowledge about respiratory metabolism during saline stress conditions is still lacking. In this context, the role of the nonphosphorylating cyanide-resistant pathway, which is a common feature of higher plant respiration (18, 28), is not fully elucidated. Some reports show that the activity ofthis alternative pathway could be modified in stress situations (17,25 MATERIALS AND METHODS Plant

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Section: Plant Materialsmentioning

confidence: 99%

Changes in Properties of Barley Leaf Mitochondria Isolated from NaCl-Treated Plants

Jolivet¹,

Pireaux²,

Dizengremel³

1990

Plant Physiol.

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“…in . Nonetheless, the function(s) of this nonphosphorylating pathway in respiratory metabolism is not well defined (Day et al, 1980;Lambers, 1985;Lance et al, 1985;Purvis and Shewfelt, 1993).…”

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confidence: 99%

Alternative Oxidase Activity in Tobacco Leaf Mitochondria (Dependence on Tricarboxylic Acid Cycle-Mediated Redox Regulation and Pyruvate Activation)

et al. 1995

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Transgenic Nicofiana tabacum (cv Petit Havana SR1) containing high levels of mitochondrial alternative oxidase (AOX) protein due t o the introduction of a sense transgene(s) of Aoxl, the nuclear gene encoding AOX, were used t o investigate mechanisms regulating AOX activity. After purification of leaf mitochondria, a large proportion of the AOX protein was present as the oxidized (covalently associated and less active) dimer. High AOX activity in these mitochondria was dependent on both reduction of the protein by DTT (to the noncovalently associated and more active dimer) and its subsequent activation by certain a-keto acids, particularly pyruvate. Reduction of AOX t o its more active form could also be mediated by intramitochondrial reducing power generated by the oxidation of certain tricarboxylic acid cycle substrates, most notably isocitrate and malate. Our evidence suggests that NADPH may be specifically required for AOX reduction. All of the above regulatory mechanisms applied to AOX in wild-type mitochondria as well. Transgenic leaves lacking AOX due t o the introduction of an Aoxl antisense transgene or multiple sense transgenes were used to investigate the potential physiological significance of the AOXregulatory mechanisms. Under conditions in which respiratory carbon metabolism is restricted by the capacity of mitochondrial electron transport, feed-forward activation of AOX by mitochondrial reducing power and pyruvate may act t o prevent redirection of carbon metabolism, such as to fermentative pathways.

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“…Mitochondrial electron transport in plants may proceed through either the CP2 or the AP (6,12,14). Transfer of electrons from NADH through the CP is coupled at three sites to the translocation of protons from the matrix to the intermembrane space.…”

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confidence: 99%

“…Although many studies indicate that plants are capable of altering the capacity of the AP (6,14), little is known about the mechanisms by which this occurs. Some studies show that inhibition of the CP with respiratory inhibitors increases AP respiration.…”

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confidence: 99%

Coordinate Regulation of Cytochrome and Alternative Pathway Respiration in Tobacco

Vanlerberghe

McIntosh²

1992

Plant Physiol.

103

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In suspension cells of NT1 tobacco (Nicotiana tabacum L. cv bright yellow), inhibition of the cytochrome pathway of respiration with antimycin A induced a large increase in the capacity of the alternative pathway over a period of approximately 12 h, as confirmed in both whole cells and isolated mitochondria. The increase in alternative pathway capacity required de novo RNA Mitochondrial electron transport in plants may proceed through either the CP2 or the AP (6,12,14). Transfer of electrons from NADH through the CP is coupled at three sites to the translocation of protons from the matrix to the intermembrane space. Reentry of protons to the matrix through complex V (mitochondrial ATP synthetase) results in the production of ATP. In this case, carbon oxidation in respiration is coupled to the production of ATP, and in many instances respiration rate is tightly regulated by the availability of ADP (i.e. adenylate control) (8, 12). Transfer of electrons through the AP bypasses two of the three sites of proton translocation. Under these conditions, carbon oxidation is not as tightly coupled to the production of ATP, and it is expected that respiration rate would not be as strictly regulated by the availability of ADP (8,12 It seems imperative that plants be able to regulate in a coordinate fashion the partitioning of electrons between the CP and the AP to meet changing metabolic requirements. Two important factors to be regulated will be, first, the capacity of each pathway to transfer electrons, and second, the degree to which that capacity is used (i.e. the degree of engagement of the pathway). The degree of engagement of the AP is dependent upon the redox poise of the ubiquinone pool (9) and, to some extent, upon the substrates being oxidized by the mitochondria (7).Although many studies indicate that plants are capable of altering the capacity of the AP (6, 14), little is known about the mechanisms by which this occurs. Some studies show that inhibition of the CP with respiratory inhibitors increases AP respiration. For example, treatment of rice roots with low concentrations of KCN or NaN3 for 6 h resulted in increased CN-resistant respiration, although it was not shown whether this CN-resistant respiration was sensitive to SHAM (11). In pea roots, a CN-resistant and SHAM-sensitive component of respiration was induced after several hours of KCN treatment (28). From the above reports, it is not clear whether the KCN treatment increased the capacity or simply the engagement of the AP. Also, interpretation of the data is hampered because KCN is known to inhibit many enzymes of metabolism (29). Nevertheless, inhibition of the CP by a specific respiratory inhibitor may be a useful tool to study mechanisms of induction of AP capacity in plants.AA is a specific inhibitor that blocks electron transfer between Cyt b and cl in the CP (20,23). In Euglena gracilis, addition of AA induced CN-resistant respiration within 5 h (2-4). A similar induction was seen in the yeast Hansenula anomala (17) and led to the ide...

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The Cyanide-Resistant Pathway of Plant Mitochondria

Cited by 98 publications

References 139 publications

Changes in Properties of Barley Leaf Mitochondria Isolated from NaCl-Treated Plants

Changes in Properties of Barley Leaf Mitochondria Isolated from NaCl-Treated Plants

Alternative Oxidase Activity in Tobacco Leaf Mitochondria (Dependence on Tricarboxylic Acid Cycle-Mediated Redox Regulation and Pyruvate Activation)

Coordinate Regulation of Cytochrome and Alternative Pathway Respiration in Tobacco

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