Activities of principal photosynthetic and photorespiratory enzymes in leaf mesophyll and bundle sheath protoplasts from the C3-C4 intermediate flaveria ramosissima

Brandon D. Moore, Russell K. Monson, Maurice S.B. Ku, Gerald E. Edwards

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Mesophyll and bundle sheath protoplasts were differentially isolated for the first time from leaves of a C3-C4 intermediate, Flaveria ramosissima. Protoplasts were partially purified from leaf digests following differential centrifugation and flotation on dextran step-gradients. Two mesophyll and one bundle sheath fraction were obtained, with relative purities of the preparations determined visually as >95% for mesophyll and >80% for bundle sheath.Representative C3 and C4 photosynthetic enzymes had substantial activities, on a chlorophyll basis, in all three protoplast preparations. The activity of phosphoenolpyruvate carboxylase was highest in the lower density mesophyll fraction and lowest in the bundle sheath fraction. Conversely, the activity of NADP-malic enzyme was highest in the bundle sheath, and lowest in the lighter mesophyll preparation. Ribulose 1,5-bisphosphate carboxylase/oxygenase had similar activity in all three preparations, as did glycolate oxidase. However, glycine decarboxylase was about 3-fold enriched in the bundle sheath fraction. The data indicate that the partial compartmentation of photorespiratory metabolism may contribute along with limited C4 photosynthesis to reducing photorespiration in this intermediate species.

Original languageEnglish (US)
Pages (from-to)999-1006
Number of pages8
JournalPlant and Cell Physiology
Volume29
Issue number6
StatePublished - Sep 1 1988
Externally publishedYes

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Keywords

  • C3-C4
  • Flaveria ramosissima
  • Intermediate
  • Photorespiration
  • Protoplast

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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