Quantifying ATP turnover in anoxic coleoptiles of rice (Oryza sativa) demonstrates preferential allocation of energy to protein synthesis

Joshua M. Edwards, Thomas H. Roberts, Brian J. Atwell*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    54 Citations (Scopus)
    45 Downloads (Pure)

    Abstract

    Oxygen deprivation limits the energy available for cellular processes and yet no comprehensive ATP budget has been reported for any plant species under O2 deprivation, including Oryza sativa. Using 3-d-old coleoptiles of a cultivar of O. sativa tolerant to flooding at germination, (i) rates of ATP regeneration in coleoptiles grown under normoxia (aerated solution), hypoxia (3% O2), and anoxia (N2) and (ii) rates of synthesis of proteins, lipids, nucleic acids, and cell walls, as well as K+ transport, were determined. Based on published bioenergetics data, the cost of synthesizing each class of polymer and the proportion of available ATP allocated to each process were then compared. Protein synthesis consumed the largest proportion of ATP synthesized under all three oxygen regimes, with the proportion of ATP allocated to protein synthesis in anoxia (52%) more than double that in normoxic coleoptiles (19%). Energy allocation to cell wall synthesis was undiminished in hypoxia, consistent with preferential elongation typical of submerged coleoptiles. Lipid synthesis was also conserved strongly in O2 deficits, suggesting that membrane integrity was maintained under anoxia, thus allowing K+ to be retained within coleoptile cells. Rates of protein synthesis in coleoptiles from rice cultivars with contrasting tolerance to oxygen deficits (including mutants deficient in fermentative enzymes) confirmed that synthesis and turnover of proteins always accounted for most of the ATP consumed under anoxia. It is concluded that successful establishment of rice seedlings under water is largely due to the capacity of coleoptiles to allocate energy to vital processes, particularly protein synthesis.

    Original languageEnglish
    Pages (from-to)4389-4402
    Number of pages14
    JournalJournal of Experimental Botany
    Volume63
    Issue number12
    DOIs
    Publication statusPublished - Jul 2012

    Bibliographical note

    Copyright The Author 2012. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: [email protected]

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