H+ Transport by K+ EXCHANGE ANTIPORTER3 Promotes Photosynthesis and Growth in Chloroplast ATP Synthase Mutants. Issue 4 (10th February 2020)

• Record Type: Journal Article
• Authors: Correa Galvis, Viviana; Strand, Deserah D.; Messer, Michaela; Thiele, Wolfram; Bethmann, Stephanie; Hübner, Dennis; Uflewski, Michal; Kaiser, Elias; Siemiatkowska, Beata; Morris, Bethan A.; Tóth, Szilvia Z.; Watanabe, Mutsumi; Brückner, Franziska; Höfgen, Rainer; Jahns, Peter; Schöttler, Mark Aurel; Armbruster, Ute
• Is Part Of: Plant physiology. Volume 182:Issue 4(2020)
• Page Start: 2126
• Page End: 2142
• Publication Date: 2020-02-10
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.19.01561
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : Proton antiport across the thylakoid membrane up-regulates photosynthesis and growth in an Arabidopsis mutant with low chloroplast ATP synthase levels and high proton motive force. 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 (Ɗψ) component to allow for a higher fraction of pmf stored as a proton concentration gradient (ƊpH). K + /H + antiport across the thylakoid membrane via K+ EXCHANGE ANTIPORTER3 (KEA3) instead reduces the ƊpH fraction of the pmf. Thereby, KEA3 decreases nonphotochemical 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 ( 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 reduced 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 b 6 f complex. Overexpression of KEA3 in the cgl160 background reduces 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 ƊpH benefits photosynthesis and growth.