Reduced glutamine synthetase activity plays a role in control of photosynthetic responses to high light in barley leaves

Marian Brestic, Marek Zivcak, Katarina Olsovska, Hong Bo Shao, Hazem M. Kalaji, Suleyman I. Allakhverdiev

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

The chloroplastic glutamine synthetase (GS, EC 6.3.1.2) activity was previously shown to be the limiting step of photorespiratory pathway. In our experiment, we examined the photosynthetic high-light responses of the GS2-mutant of barley (Hordeum vulgare L.) with reduced GS activity, in comparison to wild type (WT). The biophysical methods based on slow and fast chlorophyll fluorescence induction, P700 absorbance, and gas exchange measurements were employed. Despite the GS2 plants had high basal fluorescence (F0) and low maximum quantum yield (Fv/Fm), the CO2 assimilation rate, the PSII and PSI actual quantum yields were normal. On the other hand, in high light conditions the GS2 had much higher non-photochemical quenching (NPQ), caused both by enhanced capacity of energy-dependent quenching and disconnection of PSII antennae from reaction centers (RC). GS2 leaves also maintained the PSII redox poise (QA-/QA total) at very low level; probably this was reason why the observed photoinhibitory damage was not significantly above WT. The analysis of fast chlorophyll fluorescence induction uncovered in GS2 leaves substantially lower RC to antenna ratio (RC/ABS), low PSII/PSI ratio (confirmed by P700 records) as well as low PSII excitonic connectivity.

Original languageEnglish
Pages (from-to)74-83
Number of pages10
JournalPlant Physiology and Biochemistry
Volume81
DOIs
Publication statusPublished - Aug 2014

Keywords

  • Barley
  • Chlorophyll fluorescence
  • Glutamine synthetase
  • Non-photochemical quenching
  • Photoinhibition
  • Photorespiration

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

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