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Functional absorption cross section (s'PSII) and 'apparent' optical cross section (a'PSII) of PSII sensed at a distance with LIFT/FRRF: detection and characterization of PSII reaction centers and antenna size in-situ

Conference Paper


Abstract


  • A light induced fluorescence transient instrument (LIFT) operated with the fast repetition rate

    fluorescence protocol (FRRF) was used to measure PSII functional and optical absorption cross

    sections (σPSII and aPSII). It became clear that small antenna mutants of barley and arabidopsis

    displayed smaller steady state values of σPSII and aPSII in the dark, and that spinach or arabidopsis

    grown in, or transferred to, low irradiance produced larger values of these parameters. Dynamic

    changes in σ’PSII and a’PSII in the light were followed during state transitions (ST) and NPQ in situ.

    Spot assays of ST+ and ST- genotypes of barley and arabidopsis measured with LIFT/FRRF and PAM

    were similar, but larger changes were observed in σ’PSII and a’PSII. With time resolution of 2-6 seconds

    the simultaneous, less intrusive LIFT/FRRF measurements of ϕ’PSII, σ’PSII (from which a’PSII= σ’PSII /

    ϕ’PSII), t½ for ETR QA-PQ and PQ-PSI, PQ redox-status and Ek (simulated PFD½ for ETR) offered

    holistic insights into ST and NPQ in-situ. For example, ETR responses to light 2 and light 2+1 in

    asLhcb2-12 (ST-) resembled six ST+ genotypes, whereas QA flash relaxation kinetics were symptomatic

    of persistent PQ over-reduction in stn7 and stn7/8. Ek always increased with NPQ and declined on

    inhibition of NPQ. Impaired NPQ (npq1, npq4 and pgr5) or DTT treated spinach showed large increases

    in σ’PSII and a’PSII. The ratio a’PSII /aPSII increased as qP decreased (R2 = 0.98), possibly because

    excitation from closed PSII centers was transferred to connected open centers, causing an “apparent”

    increase in a’PSII.

Authors


  •   Soon, Chow Wah. (external author)
  •   Osmond, Barry B. (external author)
  •   Wyber, Rhys (external author)
  •   Robinson, Sharon
  •   Pogson, Barry (external author)
  •   Kolber, Zbigniew S. (external author)

Publication Date


  • 2016

Citation


  • Soon, C. Wah., Osmond, B., Wyber, R., Robinson, S., Pogson, B. & Kolber, Z. (2016). Functional absorption cross section (s'PSII) and 'apparent' optical cross section (a'PSII) of PSII sensed at a distance with LIFT/FRRF: detection and characterization of PSII reaction centers and antenna size in-situ. The 17th International Congress on Photosynthesis Research Photosynthesis in a Changing World (pp. 115-116).

Start Page


  • 115

End Page


  • 116

Abstract


  • A light induced fluorescence transient instrument (LIFT) operated with the fast repetition rate

    fluorescence protocol (FRRF) was used to measure PSII functional and optical absorption cross

    sections (σPSII and aPSII). It became clear that small antenna mutants of barley and arabidopsis

    displayed smaller steady state values of σPSII and aPSII in the dark, and that spinach or arabidopsis

    grown in, or transferred to, low irradiance produced larger values of these parameters. Dynamic

    changes in σ’PSII and a’PSII in the light were followed during state transitions (ST) and NPQ in situ.

    Spot assays of ST+ and ST- genotypes of barley and arabidopsis measured with LIFT/FRRF and PAM

    were similar, but larger changes were observed in σ’PSII and a’PSII. With time resolution of 2-6 seconds

    the simultaneous, less intrusive LIFT/FRRF measurements of ϕ’PSII, σ’PSII (from which a’PSII= σ’PSII /

    ϕ’PSII), t½ for ETR QA-PQ and PQ-PSI, PQ redox-status and Ek (simulated PFD½ for ETR) offered

    holistic insights into ST and NPQ in-situ. For example, ETR responses to light 2 and light 2+1 in

    asLhcb2-12 (ST-) resembled six ST+ genotypes, whereas QA flash relaxation kinetics were symptomatic

    of persistent PQ over-reduction in stn7 and stn7/8. Ek always increased with NPQ and declined on

    inhibition of NPQ. Impaired NPQ (npq1, npq4 and pgr5) or DTT treated spinach showed large increases

    in σ’PSII and a’PSII. The ratio a’PSII /aPSII increased as qP decreased (R2 = 0.98), possibly because

    excitation from closed PSII centers was transferred to connected open centers, causing an “apparent”

    increase in a’PSII.

Authors


  •   Soon, Chow Wah. (external author)
  •   Osmond, Barry B. (external author)
  •   Wyber, Rhys (external author)
  •   Robinson, Sharon
  •   Pogson, Barry (external author)
  •   Kolber, Zbigniew S. (external author)

Publication Date


  • 2016

Citation


  • Soon, C. Wah., Osmond, B., Wyber, R., Robinson, S., Pogson, B. & Kolber, Z. (2016). Functional absorption cross section (s'PSII) and 'apparent' optical cross section (a'PSII) of PSII sensed at a distance with LIFT/FRRF: detection and characterization of PSII reaction centers and antenna size in-situ. The 17th International Congress on Photosynthesis Research Photosynthesis in a Changing World (pp. 115-116).

Start Page


  • 115

End Page


  • 116