Xanthophyll cycle, light energy dissipation and photosystem II down-regulation in senescent leaves of wheat plants grown in the field

C. Lu*, Q. Lu, Jianhua ZHANG, Q. Zhang, T. Kuang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

Photosynthesis, the xanthophyll cycle, light energy dissipation and down-regulation of photosystem II (PSII) in senescent leaves of wheat plants grown in the field were investigated. With the progress of senescence, maximal efficiency of PSII photochemistry decreased only slightly early in the morning but substantially at midday. Actual PSII efficiency, photochemical quenching, efficiency of excitation capture by open PSII centres, and the I-P phase of fluorescence induction curves decreased significantly and such decreases were much more evident at midday than in the morning. At the same time, non-photochemical quenching, thermal dissipation and de-epoxidation status of the xanthophyll cycle increased, with much greater increases at midday than in the morning. These results suggest that the xanthophyll cycle played a role in photoprotection of PSII in senescent leaves by dissipating excess excitation energy. Taking into account the substantial decrease in photosynthetic capacity in senescent leaves, our data seem to support the view that the decrease in actual PSII efficiency in senescent leaves may represent a mechanism to down-regulate photosynthetic electron transport to match the decreased CO2 assimilation capacity and avoid photodamage of PSII from excess excitation energy.

Original languageEnglish
Pages (from-to)1023-1030
Number of pages8
JournalAustralian Journal of Plant Physiology
Volume28
Issue number10
DOIs
Publication statusPublished - 2001

Scopus Subject Areas

  • Agricultural and Biological Sciences(all)

User-Defined Keywords

  • Chlorophyll fluorescence
  • Leaf senescence
  • Photosynthesis
  • Photosystem II
  • Thermal energy dissipation
  • Xanthophyll cycle

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