Nonphotochemical Reduction of the Plastoquinone Pool in Sunflower Leaves Originates from Chlororespiration

Taylor S. Feild, Ladislav Nedbal, Donald R. Ort

Research output: Contribution to journalArticlepeer-review


We investigated the relationship between nonphotochemical plastoquinone reduction and chlororespiration in leaves of growth-chamber-grown sunflower (Helianthus annuus L.). Following a short induction period, leaves of previously illuminated sunflower showed a substantially increased level of minimal fluorescence following a light-to-dark transition. This increase in minimal fluorescence was reversed by far-red illumination, inhibited by rote-none or photooxidative methyl viologen treatment, and stimulated by fumigation with CO. Using flash-induced electrochromic absorption-change measurements, we observed that the capacity of sunflower to reduce plastoquinone in the dark influenced the activation state of the chloroplast ATP synthase, although chlororespiratory transmembrane electrochemical potential formation alone does not fully explain our observations. We have added several important new observations to the work of others, forming, to our knowledge, the first strong experimental evidence that chlororespiratory, nonphotochemical plastoquinone reduction and plastoquinol oxidation occur in the chloroplasts of higher plants. We have introduced procedures for monitoring and manipulating chlororespiratory activity in leaves that will be important in subsequent work aimed at defining the pathway and function of this dark electron flux in higher plant chloroplasts.

Original languageEnglish (US)
Pages (from-to)1209-1218
Number of pages10
JournalPlant physiology
Issue number4
StatePublished - 1998

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science


Dive into the research topics of 'Nonphotochemical Reduction of the Plastoquinone Pool in Sunflower Leaves Originates from Chlororespiration'. Together they form a unique fingerprint.

Cite this