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Plant Physiol. 2020 Feb 10. pii: pp.01561.2019. doi: 10.1104/pp.19.01561. [Epub ahead of print]

H+ transport by K+ EXCHANGE ANTIPORTER3 promotes photosynthesis and growth in chloroplast ATP synthase mutants.

Author information

1
Max Planck Institute of Molecular Plant Physiology CITY: Golm (Potsdam) Germany [DE].
2
Max Planck Institute for Molecular Plant Physiology CITY: Potsdam Germany [DE].
3
MPI of Molecular Plant Physiology, Golm CITY: D-14476 Potsdam-Golm STATE: Brandenburg Germany [DE].
4
Heinrich-Heine-Universitaet CITY: Duesseldorf Germany [DE].
5
Wageningen University CITY: Wageningen Netherlands [NL].
6
Biological Research Center, Szeged CITY: Szeged POSTAL_CODE: H-6726 Hungary [HU].
7
NAIST CITY: Nara Japan [JP].
8
Max Planck Institute of Molecular Plant Physiology CITY: Potsdam-Golm STATE: Brandenburg POSTAL_CODE: 14476 Germany [DE].
9
Heinrich-Heine-Universitaet CITY: Duesseldorf POSTAL_CODE: D-40225 Germany [DE].
10
MPI of Molecular Plant Physiology, Golm CITY: Potsdam-Golm STATE: Brandenburg POSTAL_CODE: 14476 Germany [DE].
11
Max Planck Institute of Molecular Plant Physiology CITY: Golm (Potsdam) POSTAL_CODE: 14476 Germany [DE] Armbruster@mpimp-golm.mpg.de.

Abstract

The composition of the thylakoid proton motive force (pmf) is regulated by thylakoid ion transport. Passive ion channels in the thylakoid membrane dissipate the membrane potential (Δψ) component to allow for a higher fraction of pmf stored as a proton concentration gradient (ΔpH). K+/H+ antiport across the thylakoid membrane via K+ EXCHANGE ANTIPORTER3 (KEA3) instead reduces the ΔpH fraction of the pmf. Thereby, KEA3 decreases non-photochemical quenching (NPQ), thus allowing for higher light use efficiency, which is particularly important during transitions from high to low light. Here, we show that in the background of the Arabidopsis thaliana chloroplast (cp)ATP synthase assembly mutant cgl160, with decreased cpATP synthase activity and increased pmf amplitude, KEA3 plays an important role for photosynthesis and plant growth under steady state conditions. By comparing cgl160 single with cgl160 kea3 double mutants, we demonstrate that in the cgl160 background loss of KEA3 causes a strong growth penalty. This is due to a decreased photosynthetic capacity of cgl160 kea3 mutants, as these plants have a lower lumenal pH than cgl160 mutants, and thus show substantially increased pH-dependent NPQ and decreased electron transport through the cytochrome b6f complex. Overexpression of KEA3 in the cgl160 background decreases pH-dependent NPQ and increases photosystem II efficiency. Taken together, our data provide evidence that under conditions where cpATP synthase activity is low, a KEA3-dependent reduction of ΔpH benefits photosynthesis and growth.

PMID:
32041909
DOI:
10.1104/pp.19.01561
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