Effect of Iron Deficiency on the Respiration of Sycamore (Acer pseudoplatanus L.) Cells

Abstract

The effects of iron deficiency on cell culture growth, cell respiration, mitochondrial oxidative properties, and the eledron transport chain were studied with suspension-cultured sycamore (Acer pseudoplatanus 1.) cells. lron deprivation considerably decreased the initial growth rates and limited the maximum density of the cells. Under these conditions, the cells remained swollen throughout their growth. The absence of iron led to a steady decline in the uncoupled rate of Oz consumption. When the uncoupled rate of 0 2 uptake closely approximated the respiratory rate, the cells began to collapse. At this stage, the leve1 of all the cytochromes and eledron paramagnetic resonance-detedable Fe-S clusters of the mitochondrial inner membrane were dramatically decreased. Nevertheless, it appeared from substrate oxidation measurements that this overall depletion in iron-containing components solely disturbed the fundioning of complex II, whereas neither complexes I, 111, or IV, nor the machinery involved in ATP synthesis, was apparently impaired in iron-deficient mitochondria. However, our results suggest that the impairment of complex II resulted in a strong reduction of the overall capacity of the mitochondrial electron transport chain, which was responsible for determining the rate of endogenous respiration in sycamore cells. Finally, this situation led to a depletion of various energy metabolites that could contribute to the premature cell death.The great need for iron in biological systems is a consequence of its irreplaceable role as a catalyst for many intracellular reactions. An important example is mitochondrial electron transfer via Cyts and iron-sulfur (Fe-S) proteins. Thus, Ohnishi et al. (1971) demonstrated that low iron content in the growth medium of yeast cultures significantly decreased the mitochondrial content of many EPR-detectable Fe-S clusters. In addition, severe iron deficiency results in a large decrease in the activity of mitochondrial respiratory chain dehydrogenases (succinate-and NADH-ubiquinone oxidoreductases) in skeletal muscle mitochondria (Maguire et al., 1982;Ackrell et al., 1984), leading to a decrease in mitochondrial respiratory activity. Likewise, Cartier et al. turbation of respiration in plants by iron deficiency. The concepts of iron function in cell respiration are being explored both in animal systems and in yeast, providing an important reference point. Nevertheless, crucial differences in the impact of iron deficiency on cell respiration between plants and animals may exist and thus we must not hastily embrace the findings using mammalian cells until key experiments on plant cells have been completed.In this context, we undertook the present study to analyze the effects of iron deficiency on plant cell culture growth and respiratory metabolism. Plant cell-suspension cultures rapidly generate large amounts of cell material that offer a useful tool for studying plant cell physiology. MATERIALS AND METHODS Biological MaterialSycamore (Acer pseudoplatanus L.) cells were grown at ...

Iron deficiency induces changes in riboflavin secretion and the mitochondrial electron transport chain in hairy roots of Hyoscyamus albus

“…Previously, rhizodermal transfer cell formation has been observed in swollen root tips under Fe deficiency, where an increase in the number of mitochondria has been found (Landsberg, 1986). Similar results have been obtained with sycamore cells (Pascal and Douce, 1993) and cucumber roots (Dell'Orto et al, 2002). This increase in the number of mitochondria is likely to affect the respiratory activity, including the mtETC.…”

Arrest of mitochondrial biogenesis in copper‐treated sycamore cells

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