title: Photoinhibition of Photosystem I in field-grown barley (Hordeum vulgare L.): Induction, recovery and acclimation.
abstract: The effects of exposure of a field-grown winter cultivar of barley (Hordeum vulgare L.) to Photosystem I (PS I) photoinhibitory conditions in the form of bright day-light combined with chilling conditions were investigated. PS I photoinhibition was manifested by damage to the Fe-S centers of PS I and to the PS I-A/B polypeptides. Up to 20% of the PS I complexes were photoinactivated. Upon transfer to room temperature, the plants partially recovered from PS I photoinhibition, although damage was still detectable after one week. These results demonstrate that PS I photoinhibition is a physiologically relevant phenomenon in chilling-tolerant plants grown under field conditions. In order to study the induction of cyclic electron transport around PS I by PS I photoinhibitory conditions, antibodies raised against the NDH-I subunit of the NDH complex (a component of cyclic electron transport) were used to measure NDH levels in the exposed plants. A marked increase in the amount of NDH complex and a corresponding increase in NADPH dehydrogenase activity in the thylakoids were observed. The data indicate that the response to PS I-photoinhibitory conditions may involve regulated changes in cyclic electron transport around PS I.
authors.affiliation: Center of Molecular Plant Physiology (PlaCe), Plant Biochemistry Laboratory, Department of Plant Biology, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Copenhagen, Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Bernhard Teicher
authors.forename: B
authors.initials: B
authors.lastname: Lindberg Møller
authors.forename: H
authors.initials: H
authors.lastname: Vibe Scheller