Photosynthetica

, 44:439

Photoinhibition and xanthophyll cycle activity in bayberry (Myrica rubra) leaves induced by high irradiance

  • Y. -P. Guo
  • D. -P. Guo
  • H. -F. Zhou
  • M. -J. Hu
  • Y. -G. Shen
Original Papers

DOI: 10.1007/s11099-006-0048-z

Cite this article as:
Guo, Y.P., Guo, D.P., Zhou, H.F. et al. Photosynthetica (2006) 44: 439. doi:10.1007/s11099-006-0048-z

Abstract

The effect of high irradiance (HI, photosynthetically active photon flux density of 1 300 µmol m−2 s−1) on net photosynthetic rate (PN), chlorophyll fluorescence parameters, and xanthophyll cycle components were studied in fruit tree bayberry leaves. HI induced the photoinhibition and inactivation of photosystem 2 (PS2) reaction centres (RCs), which was characterized by decreased PN, maximum yield of fluorescence after dark adaptation (Fm), photochemical efficiency of PS2 (Fv/Fm) and quantum yield of PS2 (ΦPS2), and increased reduction state of QA (1-qP) and non-photochemical quenching (NPQ). Initial fluorescence (F0) showed a decrease after the first 2 h, and subsequently increased from the third hour exposure to HI. Furthermore, a greater increase in the ratio (Fi-F0)/(Fp-F0) which is an expression of the proportion of the QB non-reducing PS2 centres, whereas a remarked decrease in the slope of Fi to Fp which represents the rate of QA reduction was observed in leaves after HI exposure. Additionally, HI caused an increase in the pool size of the xanthophyll cycle pigments and sustained elevated contents of zeaxanthin (Z), antheraxanthin (A), and de-epoxidation state (DES) at the end of the irradiation period. During HI, decreased Fm, Fv/Fm, ΦPS2, NPQ, slope of Fi to Fp, V+A+Z, and DES, and increased F0, 1-qP, ratio (Fi-F0)/(Fp-F0), and V were observed in dithiothreitol (DTT)-fed leaves compared to control ones under the same conditions. Hence photoinhibition caused by HI in bayberry was probably attributed to inactivation of PS2 RCs, and photoprotection from photodamage were mainly related to the xanthophyll cycle-dependent heat dissipation in excess photons.

Additional key words

chlorophyll fluorescencedithiothreitolintercellular CO2 concentrationnet photosynthetic ratephotosystem 2 reaction centres

Abbreviations

A

antheraxanthin

Ca

ambient CO2 concentration

Ci

intercellular CO2 concentration

Chl

chlorophyll

DES

deepoxidation state of the xanthophyll cycle pigments

DTT

dithiothreitol

Fm

maximum yield of fluorescence after dark adaptation

F0

initial fluorescence

Fv/Fm

maximum photochemical efficiency of PS2 with all reaction centres open

NPQ

non-photochemical quenching

PFD

photon flux density

PN

net photosynthetic rate

PS2

photosystem 2

RC

reaction centre

V

violaxanthin

Z

zeaxanthin

1-qP

reduction state of QA

ΦPS2

quantum yield of PS2

Copyright information

© Institute of Experimental Botany, ASCR 2006

Authors and Affiliations

  • Y. -P. Guo
    • 1
    • 2
  • D. -P. Guo
    • 1
    • 2
  • H. -F. Zhou
    • 1
  • M. -J. Hu
    • 1
  • Y. -G. Shen
    • 3
  1. 1.Department of Horticulture, College of Agriculture and BiotechnologyZhejiang UniversityHangzhouP.R. China
  2. 2.Key Laboratory of Horticultural Plant Development and BiotechnologyMinistry of AgricultureHangzhouP.R. China
  3. 3.Institute of Plant Physiology and EcologyThe Chinese Academy of SciencesShanghaiP.R. China