Disentangling the sites of non-photochemical quenching in vascular plants

Abstract

In nature, plants experience large fluctuations in light intensity and they need to balance the absorption and utilization of this energy accordingly. Non-photochemical quenching (NPQ) is a rapidly-switchable mechanism which protects plants from photodamage caused by high light exposure by dissipating the energy absorbed in excess as heat. It is triggered by the ΔpH across the thylakoid membrane and requires the presence of the protein PsbS and the xanthophyll zeaxanthin. However, the site and mechanism of the quencher(s) remain equivocal. Here, we constructed a mutant of Arabidopsis thaliana which lacks LHCII, the main antenna complexes of plants, to verify its contribution to NPQ. The mutant has normally stacked thylakoid membranes, displays no upregulation of other LHCs but shows a relative decrease in PSI which compensates for the decrease of the PSII antenna. The mutant exhibits a ~60% reduction in NPQ, while the remaining NPQ resembles that of the Chl bless mutant, which lacks all PSII peripheral antenna complexes. We thus report that PsbS-dependent NPQ mainly occurs within LHCII, but there is an additional quenching site within the PSII core. Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

A Chlorophyte Alga Utilizes Alternative Electron Transport for Primary Photoprotection

“…2). This agrees with the consensus that NPQ is predominantly located in the major antennae of chlorophytes and vascular plants (Goral et al, 2012;Nicol et al, 2019), and that D. armatus has a constitutively small antennae protein network.…”

“…This process becomes important for avoiding damage to the photosynthetic system when absorbed light energy cannot be fully utilized by the light-harvesting reactions. NPQ is triggered by a DpH gradient across the thylakoid membrane that leads to conformational changes in the light-harvesting antennae associated with PSII (Goral et al, 2012;Nicol et al, 2019).…”

Lipid Dependence of Xanthophyll Cycling in Higher Plants and Algae

“…Recently, it has been demonstrated that PsbS-dependent NPQ occurs mainly in the LHCII whereas another quenching site operates within the PSII core complex (Nicol et al, 2019). For plants containing the Lx cycle and green algae exhibiting the shortened Vx/Ax cycle it was demonstrated that L or Ax can play a similar role in NPQ induction and enhancement as it is normally observed for Zx (Goss et al, 1998;Garcia-Plazaola et al, 2003;Leonelli et al, 2017).…”

Ascorbate and Thiamin: Metabolic Modulators in Plant Acclimation Responses

“…Apart from the xanthophyll zeaxanthin, PsbS is known as another component of NPQ [51]. PsbS-dependent quenching site has been recently deciphered to be in Light-harvesting complex II (LHCII), and in the PSII core, most likely in the core antenna complexes CP43 and/or CP47 [52]. In the study of Giacomelli and coworkers, PsbS protein was up-regulated more than twofold upon transition to high light, however, it remained unchanged in the vtc2, which is in line with the observation that vtc2 mutants have reduced levels of non-photochemical quenching [47].…”