A comparative chlorophyll a fluorescence study on isolated cells and intact leaves of Bouteloua gracilis (blue grama grass)

Authors: JIMÉNEZ-FRANCISCO, B - Postgraduate College; STIRBET, A - Retired Non ARS Employee; AGUADO-SANTACRUZ, G - Technical Institute Of Mexico; CAMPOS, H - Postgraduate College; CONDE-MARTÍNEZ, F - Postgraduate College; PADILLA-CHACÓN, D - Postgraduate College; TREJO, J - Postgraduate College; Bernacchi, Carl; GOVINDJEE, G - University Of Illinois

Submitted to: Photosynthetica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2019
Publication Date: 5/28/2020
Citation: Jiménez-Francisco, B., Stirbet, A., Aguado-Santacruz, G.A., Campos, H., Conde-Martínez, F.V., Padilla-Chacón, D., Trejo, J., Bernacchi, C.J., Govindjee, G. 2020. A comparative chlorophyll a fluorescence study on isolated cells and intact leaves of Bouteloua gracilis (blue grama grass). Photosynthetica. 58(Special Issue):262-274. https://doi.org/10.32615/ps.2019.148.
DOI: https://doi.org/10.32615/ps.2019.148

Interpretive Summary: Blue gamma grass is a drought and grazing tolerant grass species. To understand the mechanisms behind their ability to withstand drought, both leaves and isolated cells were measured using a technique to measure how light, absorbed through photosynthesis, is used. To do this, different sucrose concentrations and different carbon dioxide concentrations were applied to leave and isolated cells to determine whether the isolated cells behave similar to leaves. If so, then the isolated cells will be easier to measure rather than having to wait for whole plants to be grown. The results show that similarity exists in the measurements of leaves and isolated cells, although they respond differently to the sucrose and carbon dioxide treatments.

Technical 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.