, Volume 208, Issue 4, pp 472–479

Ultrastructure of chloroplast protuberances in rice leaves preserved by high-pressure freezing


  • Timothy M. Bourett
    • DuPont Agricultural Products, P.O. Box 80402, Wilmington, DE 19880-0402, USA
  • Kirk J. Czymmek
    • University of Delaware, Department of Biological Sciences, Newark, DE 19713, USA
  • Richard J. Howard
    • DuPont Agricultural Products, P.O. Box 80402, Wilmington, DE 19880-0402, USA

DOI: 10.1007/s004250050584

Cite this article as:
Bourett, T., Czymmek, K. & Howard, R. Planta (1999) 208: 472. doi:10.1007/s004250050584


High-pressure freezing and freeze substitution were used to prepare leaves of rice (Oryza sativa L.) for ultrastructural analysis. Under these preparative conditions, plastid-derived stroma-containing protuberances were preserved and described with the electron microscope for the first time. Similar protuberances were observed previously only in living cells examined with the light microscope. Infoldings of the chloroplast inner envelope were a prominent ultrastructural feature of protuberances. Infoldings were also observed in the main body of the chloroplasts and sometimes appeared contiguous with thylakoid membranes. Protuberances also contained infoldings in the form of bifurcated tubules. Apparent interconnection between protuberances of adjacent plastids was observed only in one instance. A distinct gradient in the staining density of thylakoid lumina appeared to be a function of grana position and orientation relative to the cell wall. Immunocytochemistry was used to determine that the stroma within protuberances contained 1,5-bisphosphate carboxylase/oxygenase enzyme.

Key words: Chloroplast developmentChloroplast protuberancesFreeze substitutionOryza (chloroplast structure)Stromule
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© Springer-Verlag Berlin Heidelberg 1999