Special issue in honour of Prof. Reto J. Strasser - A comparative chlorophyll a fluorescence study on isolated cells and intact leaves of Bouteloua gracilis (blue grama grass)

Abstract

Bouteloua gracilis (blue grama grass) is one of the most drought and grazing tolerant plants in the short-grass ecosystem. To obtain information on their photosystem activities, we measured the fast (< 1 s) chlorophyll a fluorescence transient (the OJIP curve) from their leaves, and isolated cells grown photoautotrophically in suspension in a culture medium, or with added sucrose. One of our goals was to study the effect of different sucrose concentrations (0, 0.15, 0.3, and 3%) on PSII activity in isolated cells. Our results on cells suspended in culture medium, using the JIP-test, showed a decrease in PSII activity at increasing sucrose concentrations, while the photoautotrophic cells showed an optimal PSII activity, close to that of the leaves. Further, our data on cells grown in 0, 0.15, and 0.3% sucrose, but with added CO2, and measured while the cells were deposited on filter paper, indicate that supplementary CO2 can increase the PSII activity in the presence of sucrose, although further research is necessary to understand these results. Additional key words: kinetic parameters of the O-J, J-I, and I-P phases; osmotic stress; performance index. (G. Govindjee), catre@colpos.mx (C. Trejo) Abbreviations: Area (as related to chlorophyll a fluorescence induction curve) -area between the OJIP transient and the horizontal line at maximum fluorescence, FM; Chl -chlorophyll; ChlFI -chlorophyll a fluorescence induction; DCMU (diuron) -3-(3,4-dichlorophenyl)-1,1-dimethylurea; FK, FJ (fluorescence at the J level), FI (fluorescence at the I level), and FP (fluorescence at the P level) -chlorophyll a fluorescence at 0.3, 2, 30 ms, and at the peak P of chlorophyll a fluorescence induction, respectively; FM -maximum Chl a fluorescence; FO -minimum Chl a fluorescence (fluorescence at the O level); FV -the (maximum) variable fluorescence, which is FM -FO; OEC -oxygen-evolving complex; OJIP transient -the Chl a fluorescence transient from FO to FP; PQ -plastoquinone; PSI -photosystem I; PSII -photosystem II; QA and QB -primary and secondary plastoquinone electron acceptors of the photosystem II.Acknowledgements: Govindjee thanks the staff of Information Technology in Life Sciences at the University of Illinois at Urbana-Champaign (UIUC) for their help with the use of computers; he is also grateful to the staff of the

Overexpression of cytoplasmic C4Flaveria bidentis carbonic anhydrase in C3Arabidopsis thaliana increases amino acids, photosynthetic potential, and biomass

“…In the Chl a fluorescence induction (OJIP) curve, normalized at the ‘O’ level ( F o ), we observe, in the transgenics, a faster JI rise as well as a faster IP rise; this may be due to higher efficiency of electron transport in the transgenics (Figure 4c ; cf. Kandoi et al ., 2016 ; Jiménez‐Francisco et al ., 2020 ). The faster IP rise in the transgenics suggests higher photosynthesis efficiency (cf.…”