High light induced ROS and their effects on photoinhibition in <i>Arabidopsis thaliana</i> mutants with reduced amount of light harvesting complexes
| Authors | |
|---|---|
| Year of publication | 2007 |
| Type | Article in Proceedings |
| Conference | 12th Congress of European Society for Photobiology, Book of abstracts |
| MU Faculty or unit | |
| Citation | |
| Field | Biophysics |
| Keywords | photoinhibition; chlorophyll fluorescence; imaging; reactive oxygen species; antioxidants |
| Description | Plant photosynthetic apparatus has several regulatory mechanisms that protect plants against negative effects of high light-induced reactive oxygen species (ROS). In last decade, role of zeaxanthin, PsB protein, and light harvesting complexes (LHC) in npq mutants of Arabidopsis thaliana is studied. These mechanisms contribute to non-photochemical quenching (NPQ) of light energy absorbed in chloroplasts. Recently, the role of amount and arrangement of LHC of photosystem II (PS II) in NPQ is investigated. The aim of our work was to quantify the effect of reduced number of LHCs on sensitivity of Arabidopsis thaliana to photoinhibition. In our experiments, we used plants with limited number of LHCs, LHC proteins, main subunit of LHC II and total chlorophyl. Experimental plants exhibited either 20 % (Lhcb2-1) or 40 % (Lhcb2-12) reduction of the above components. The Lhcb2-1, Lhcb2-12 mutants and wild type (wt) control plants of Arabidopsis thaliana (Columbia) were grown under controlled conditions (16/8 h d/n photoperiod, teplota 21/19 oC d/n air temperature, relative air humidity of 55 %, photosynthetically active radiation 140 micromol m-2 s-1) for 42 d. Then, plants were exposed to a short-term high light stress (30 min, 2000 micromol m-2 s-1 of photosynthetically active radiation) that induced photoinhibition. Several methods were tested to quantify ROS production due to high-light treatment. The extent of photoinhibition and the rate of consequent was evaluated using chlorophyll fluorescence parameters (fluorometer HFC-010, PSI, CZ). Dynamics of capacity of photochemical processes in PS II (Fv/Fm) as well as actual quantum yield of PS II (Yield PS II) was measured and the fast and slow phase of Fv/FM and Yield PS II distinguished. Using the same approach, NPQ and its components qE, qI were evaluated. |
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