Analysis of <i>A. thaliana</i> resistence to high light stress and reactive oxygen species formation using biophysical methods
| Title in English | Analysis of A. thaliana resistence to high light stress and reactive oxygen species formation using biophysical methods |
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| Authors | |
| Year of publication | 2008 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Using several biophysical and biochemical techniques, we studied regulatory mechanisms that protect photosynthetic apparatus, chloroplast and thylakoid membrane components in particular, against negative effects of high light-induced reactive oxygen species (ROS). In control (wt) and mutant plants of A. thaliana, the effect of excess light on primary photosynthetic processes was investigated by several chlorophyll fluorescence techniques, chlorophyll fluorescence imaging in particular. The aim was to quantify the effects of (1) reduced number of light harvesting complexes (LHCs), (2) reduced ability to quench excess light in photosystem II (3) application of electron transport blocker in photosystem II (DCMU) on sensitivity of Arabidopsis thaliana to photoinhibition. In our experiments, we used plants with (a) reduced number of LHCs, LHC proteins, main subunit of LHC II and total chlorophyll. Experimental plants exhibited either 20 % (Lhcb2-1) or 40 % (Lhcb2-12) reduction of the above components, and (b) npq mutants. After controlled phototinhibitory treatment (30 min, 2000 micromol m-2 s-1), Fv/Fm, Yield PS II, NPQ and qE, qI were measured in 60 min interval. Effect of photoinhibition was studied also by fast chlorophyll fluorescence induction kinetics (OJIPs) recorded before and after photoinhibitory treatment. The results indicated that reduced number of LHCs altered functioning of PS II, especially in quenching of excess light energy. However, capacity of photoprotective mechanisms in A. thaliana was sufficient to cope with a short-term stress in PS II. |
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