Modulation by phytochrome of the blue light-induced extracellular acidification by leaf epidermal cells of pea (Pisum sativum L.): a kinetic analysis

JTM Elzenga*, M Staal, HBA Prins

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)

Abstract

Blue light induces extracellular acidification, a prerequisite of cell expansion, in epidermis cells of young pea leaves, by stimulation of the proton pumping-ATPase activity in the plasma membrane. A transient acidification, reaching a maximum 2.5-5 min after the start of the pulse, could be induced by pulses as short as 30 msec. A pulse of more than 3000 mu mol m(-2) saturated this response. Responsiveness to a second light pulse was recovered with a time constant of about 7 min. The fluence rate-dependent lag time and sigmoidal increase of the acidification suggested the involvement of several reactions between light perception and activation of the ATPase. In wild-type pea plants, the fluence response relation for short light pulses was biphasic, with a component that saturates at low fluence and one that saturates at high fluence. The phytochrome-deficient mutant pcd2 showed a selective loss of the high-fluence component, suggesting that the high-fluence component is phytochrome-dependent and the low-fluence component is phytochrome-independent. Treatment with the calmodulin inhibitor W7 also led to the elimination of the phytochrome-dependent high-fluence component. Simple models adapted from the one used to simulate blue light-induced guard cell opening failed to explain one or more elements of the experimental data. The hypothesis that phytochrome and a blue light receptor interact in a short-term photoresponse is endorsed by model calculations based upon a three-step signal transduction cascade, of which one component can be modulated by phytochrome.

Original languageEnglish
Pages (from-to)377-389
Number of pages13
JournalPlant Journal
Volume22
Issue number5
Publication statusPublished - Jun-2000

Keywords

  • SIGNAL-TRANSDUCTION
  • RECEPTOR CRYPTOCHROME-1
  • ARABIDOPSIS DEVELOPMENT
  • MAIZE COLEOPTILES
  • ARGENTEUM MUTANT
  • CIRCADIAN CLOCK
  • VICIA-FABA
  • PROTOPLASTS
  • PROTEIN
  • EXPRESSION

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