Photoinhibition of PS II and ELIP dynamics in Arabidopsis thaliana exposed to high light stress
| Authors | |
|---|---|
| Year of publication | 2007 |
| Type | Article in Proceedings |
| Conference | 4th Tri-National Arabidopsis Meeting, Book of Abstracts |
| MU Faculty or unit | |
| Citation | |
| Web | http://www.tnam.ac.at |
| Field | Botany |
| Keywords | light harvesting complexes; photosystem II; reactive oxygen species; early light inducible proteins; oxidative stress |
| Description | Plants were exposed to photoinhibitory treatment (30 min, PAR=2000 micromol m2 s1), see Fig. 1 B. Photoinhibition of primary photochemical processes of photosynthesis as well as consequent recovery were evaluated by severeal chlorophyll fluorescence parameters (fluorometer HFC 010, Photon Systems Instruments, CZ). We focused on dynamics of the capacity of photochemical processes in photosystem II (Fv/Fm), actual quantum yield of photosystem II (FII), and non-photochemical quenching (NPQ). Fast Chl fluorescence transient (OJIPs) were measureed by PEA fluorometer (Hansatech, UK). Using HPLC (Waters 690, USA), we determined photoinhibition-induced changes in redox state of one of antioxidative compounds: glutathione. EPR spin trapping (EPR spectrometer MiniScope MS200 (Magnettech, Germany) was used for detemination of generation of superoxidového anionic radical and hydroxyl radical (OH) in leaf segments. First, they were incubated using 60 ml of deionized water with diluted spin traps in dark at room temperature for 17 h. After photoinhibitory treatment, the complexes spin trap radical were liberated to the solution. Then, EPR spectra of the solution were measured. Before and after photoinhibitory treatment, leaf samples for analysis of ELIP1 and ELIP2 transcripts levels were taken. Using PCR, we estimated amount of transcripts. We observed a considerable increase in both gene transcripts after 2 h lasting HL exposure. During following recovery, amount of both transcripts decreased towards initial values. Photoinhibitory treatment led to a decrease in Fv/Fm and FII to 76 to 78, and 76 to 83 %, respectively, of initial values indicating less efficient transfer of absorbed energy through PS II. Fast (30 min) and slow phase (hours) of Fv/Fm recovary was distinguished. After 2 h Fv/Fm recovered to 88 % of initial values. Plants with full (wt) and slightly reduced amount of LHC II (minus 20 %, Lhcb2-1) showed similar decrease and recovery of FII , Lhcb2 12 mutants (minus 40 %) showed different time course of FIII . |
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