Vascular plants have evolved a long-term light acclimation strategy primarily relying on the regulation of the relative amounts of light-harvesting complex II (LHCII) and of the two photosystems, photosystem I (PSI) and photosystem II (PSII). We investigated whether such a model is also valid in Selaginella martensii, a species belonging to the early diverging group of lycophytes. Selaginella martensii plants were acclimated to three natural light regimes (extremely low light (L), medium light (M) and full sunlight (H)) and thylakoid organization was characterized combining ultrastructural, biochemical and functional methods. From L to H plants, thylakoid architecture was rearranged from (pseudo)lamellar to predominantly granal, the PSII : PSI ratio changed in favour of PSI, and the photochemical capacity increased. However, regulation of light harvesting did not occur through variations in the amount of free LHCII, but rather resulted from the flexibility of the association of free LHCII with PSII and PSI. In lycophytes, the free interspersed LHCII serves a fixed proportion of reaction centres, either PSII or PSI, and the regulation of PSI–LHCII(–PSII) megacomplexes is an integral part of long-term acclimation. Free LHCII ensures photoprotection of PSII, allows regulated use of PSI as an energy quencher, and can also quench endangered PSI.

Light acclimation in the lycophyte Selaginella martensii depends on changes in the amount of photosystems and on the flexibility of the light-harvesting complex II antenna association with both photosystems

FERRONI, Lorenzo
Primo
;
BALDISSEROTTO, Costanza
Penultimo
;
PANCALDI, Simonetta
Ultimo
2016

Abstract

Vascular plants have evolved a long-term light acclimation strategy primarily relying on the regulation of the relative amounts of light-harvesting complex II (LHCII) and of the two photosystems, photosystem I (PSI) and photosystem II (PSII). We investigated whether such a model is also valid in Selaginella martensii, a species belonging to the early diverging group of lycophytes. Selaginella martensii plants were acclimated to three natural light regimes (extremely low light (L), medium light (M) and full sunlight (H)) and thylakoid organization was characterized combining ultrastructural, biochemical and functional methods. From L to H plants, thylakoid architecture was rearranged from (pseudo)lamellar to predominantly granal, the PSII : PSI ratio changed in favour of PSI, and the photochemical capacity increased. However, regulation of light harvesting did not occur through variations in the amount of free LHCII, but rather resulted from the flexibility of the association of free LHCII with PSII and PSI. In lycophytes, the free interspersed LHCII serves a fixed proportion of reaction centres, either PSII or PSI, and the regulation of PSI–LHCII(–PSII) megacomplexes is an integral part of long-term acclimation. Free LHCII ensures photoprotection of PSII, allows regulated use of PSI as an energy quencher, and can also quench endangered PSI.
2016
Ferroni, Lorenzo; Suorsa, Marjaana; Aro, Eva Mari; Baldisserotto, Costanza; Pancaldi, Simonetta
File in questo prodotto:
File Dimensione Formato  
2016 New Phytologist.pdf

accesso aperto

Descrizione: versione editoriale
Tipologia: Full text (versione editoriale)
Licenza: Creative commons
Dimensione 1.76 MB
Formato Adobe PDF
1.76 MB Adobe PDF Visualizza/Apri
nph13939-sup-0001-SupInfo.pdf

solo gestori archivio

Descrizione: Materiali supplementari
Tipologia: Altro materiale allegato
Licenza: Creative commons
Dimensione 1.53 MB
Formato Adobe PDF
1.53 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2351421
Citazioni
  • ???jsp.display-item.citation.pmc??? 13
  • Scopus 37
  • ???jsp.display-item.citation.isi??? 37
social impact