Characterization of photosynthetic pigment composition, photosystem II photochemistry and thermal energy dissipation during leaf senescence of wheat plants grown in the field

Congming Lu*, Qingtao Lu, Jianhua ZHANG, Tingyun Kuang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

93 Citations (Scopus)

Abstract

Photosynthetic pigment composition and photosystem II (PSII) photochemistry were characterized during the flag leaf senescence of wheat plants grown in the field. During leaf senescence, neoxanthin and β-carotene decreased concomitantly with chlorophyll, whereas lutein and xanthophyll cycle pigments were less affected, leading to increases in lutein/chlorophyll and xanthophyll cycle pigments/chlorophyll ratios. The chlorophyll a/b ratio also increased. With the progression of senescence, the maximal efficiency of PSII photochemistry decreased only slightly in the early morning (low light conditions), but substantially at midday (high light conditions). Actual PSII efficiency, photochemical quenching and the efficiency of excitation capture by open PSII centres decreased significantly both early in the morning and at midday and such decreases were much greater at midday than in the early morning. At the same time, non-photochemical quenching, zeaxanthin and antheraxanthin contents at the expense of violaxanthin increased both early in the morning and at midday, with a greater increase at midday. The results in the present study suggest that a down-regulation of PSII occurred in senescent leaves and that the xanthophyll cycle plays a role in the protection of PSII from photoinhibitory damage in senescent leaves by dissipating excess excitation energy, particularly when exposed to high light.

Original languageEnglish
Pages (from-to)1805-1810
Number of pages6
JournalJournal of Experimental Botany
Volume52
Issue number362
DOIs
Publication statusPublished - 2001

Scopus Subject Areas

  • Physiology
  • Plant Science

User-Defined Keywords

  • Chlorophyll fluorescence
  • Photosystem II photochemistry
  • Pigment composition
  • Wheat (Triticum aestivum L.)
  • Xanthophyll cycle

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