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The plastoquinone pool outside the thylakoid membrane serves in plant photoprotection as a reservoir of singlet oxygen scavengers
Author(s) -
Ksas Brigitte,
Légeret Bertrand,
Ferretti Ursula,
Chevalier Anne,
Pospíšil Pavel,
Alric Jean,
Havaux Michel
Publication year - 2018
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.13202
Subject(s) - thylakoid , plastoquinone , photoprotection , chloroplast , biology , singlet oxygen , biophysics , photosynthesis , photosystem ii , biochemistry , chemistry , botany , photochemistry , oxygen , organic chemistry , gene
The Arabidopsis vte1 mutant is devoid of tocopherol and plastochromanol (PC‐8). When exposed to excess light energy, vte1 produced more singlet oxygen ( 1 O 2 ) and suffered from extensive oxidative damage compared with the wild type. Here, we show that overexpressing the solanesyl diphosphate synthase 1 ( SPS1 ) gene in vte1 induced a marked accumulation of total plastoquinone (PQ‐9) and rendered the vte1 SPS1 oex plants tolerant to photooxidative stress, indicating that PQ‐9 can replace tocopherol and PC‐8 in photoprotection. High total PQ‐9 levels were associated with a noticeable decrease in 1 O 2 production and higher levels of Hydroxyplastoquinone (PQ‐C), a 1 O 2 ‐specific PQ‐9 oxidation product. The extra PQ‐9 molecules in the vte1 SPS1 oex plants were stored in the plastoglobules and the chloroplast envelopes, rather than in the thylakoid membranes, whereas PQ‐C was found almost exclusively in the thylakoid membranes. Upon exposure of wild‐type plants to high light, the thylakoid PQ‐9 pool decreased, whereas the extrathylakoid pool remained unchanged. In vte1 and vte1 SPS1 oex plants, the PQ‐9 losses in high light were strongly amplified, affecting also the extrathylakoid pool, and PQ‐C was found in high amounts in the thylakoids. We conclude that the thylakoid PQ‐9 pool acts as a 1 O 2 scavenger and is replenished from the extrathylakoid stock.