Appearance of a State 1 – State 2 transition during chloroplast development in the wheat leaf: Energetic and structural considerations

Andrew Webber, Neil R. Baker, Kathryn Platt‐Aloia, William W. Thomson

Research output: Contribution to journalArticle

20 Scopus citations


The ability of developing chloroplasts to dynamically regulate the distribution of excitation energy between photosystem 1 and photosystem 2, and thus perform a State 1 – State 2 transition, was examined from analyses of chlorophyll fluorescence kinetics in 4‐ and 8‐day‐old Triticum aestivum L. cv. Maris Dove leaves grown under a diurnal light regime. Chloroplasts at all stages of development in the two leaf systems could undergo a State 1 – State 2 transition, except those found in the basal 0.5 cm of the 4‐day‐old leaf. The ability to physiologically modify the excitation energy distribution between the chlorophyll matrices of the two photosystems developed after the development of mature, fully photochemically competent photosystem 2 units and the appearance of excitation energy transfer between photosystem 2 and photosystem 1. Also, changes in the degree of energetic interaction between the two photosystems, in vivo rates of electron transport and the chlorophyll a/b ratio could not be correlated with the appearance of a State 1 – State 2 transition. Ultrastructural studies demonstrated a 32% increase in the degree of thylakoid appression in chloroplasts at the base of the 8‐day‐old leaf compared to the situation in the basal 0.5 cm of the 4‐day‐old leaf. This difference in thylakoid stacking can account for the differing abilities of these two tissues to perform a State 1 – State 2 transition when considered in the context of the distribution of the two photosystems within appressed and non‐appressed regions of thylakoid membranes.

Original languageEnglish (US)
Pages (from-to)171-179
Number of pages9
JournalPhysiologia Plantarum
Issue number2
StatePublished - 1984
Externally publishedYes



  • Chlorophyll fluorescence
  • excitation energy transfer
  • photosystems 1 and 2
  • thylakoid
  • Triticum aestivum

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science
  • Cell Biology

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