Photosystem II energy use, non-photochemical quenching and the xanthophyll cycle in Sorghum bicolor grown under drought and free-air CO2 enrichment (FACE) conditions

A. B. Cousins; N. R. Adam; G. W. Wall; B. A. Kimball; P. J. Pinter; M. J. Ottman; S. W. Leavitt; A. N. Webber

doi:10.1046/j.1365-3040.2002.00935.x

Photosystem II energy use, non-photochemical quenching and the xanthophyll cycle in Sorghum bicolor grown under drought and free-air CO₂ enrichment (FACE) conditions

A. B. Cousins, N. R. Adam, G. W. Wall, B. A. Kimball, P. J. Pinter, M. J. Ottman, S. W. Leavitt, A. N. Webber

Life Sciences, School of (SOLS)

Research output: Contribution to journal › Article › peer-review

47 Scopus citations

Abstract

The present study was carried out to test the hypothesis that elevated atmospheric CO₂ (Ca) will alleviate over-excitation of the C₄ photosynthetic apparatus and decrease non-photochemical quenching (NPQ) during periods of limited water availability. Chlorophyll a fluorescence was monitored in Sorghum bicolor plants grown under a free-air carbon-dioxide enrichment (FACE) by water-stress (Dry) experiment. Under Dry conditions elevated Ca increased the quantum yield of photosystem II (øPSII) throughout the day through increases in both photochemical quenching coefficient (q_p) and the efficiency with which absorbed quanta are transferred to open PSII reaction centres (F_v′/F_m′). However, in the well-watered plants (Wets) FACE enhanced øPSII only at midday and was entirely attributed to changes in F_v′/F_m′. Under field conditions, decreases in øPSII under Dry treatments and ambient Ca corresponded to increases in NPQ but the de-epoxidation state of the xanthophyll pool (DPS) showed no effects. Water-stress did not lead to long-term damage to the photosynthetic apparatus as indicated by øPSII and carbon assimilation measured after removal of stress conditions. We conclude that elevated Ca enhances photochemical light energy usage in C₄ photosynthesis during drought and/or midday conditions. Additionally, NPQ protects against photo-inhibition and photodamage. However, NPQ and the xanthophyll cycle were affected differently by elevated Ca and water-stress.

Original language	English (US)
Pages (from-to)	1551-1559
Number of pages	9
Journal	Plant, Cell and Environment
Volume	25
Issue number	11
DOIs	https://doi.org/10.1046/j.1365-3040.2002.00935.x
State	Published - Nov 2002

Keywords

C photosynthesis
CO enrichment
Chlorophyll fluorescence
Water-stress
Xanthophyll cycle

ASJC Scopus subject areas

Physiology
Plant Science

Access to Document

10.1046/j.1365-3040.2002.00935.x

Cite this

Cousins, A. B., Adam, N. R., Wall, G. W., Kimball, B. A., Pinter, P. J., Ottman, M. J., Leavitt, S. W., & Webber, A. N. (2002). Photosystem II energy use, non-photochemical quenching and the xanthophyll cycle in Sorghum bicolor grown under drought and free-air CO₂ enrichment (FACE) conditions. Plant, Cell and Environment, 25(11), 1551-1559. https://doi.org/10.1046/j.1365-3040.2002.00935.x

Cousins, AB, Adam, NR, Wall, GW, Kimball, BA, Pinter, PJ, Ottman, MJ, Leavitt, SW & Webber, AN 2002, 'Photosystem II energy use, non-photochemical quenching and the xanthophyll cycle in Sorghum bicolor grown under drought and free-air CO₂ enrichment (FACE) conditions', Plant, Cell and Environment, vol. 25, no. 11, pp. 1551-1559. https://doi.org/10.1046/j.1365-3040.2002.00935.x

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abstract = "The present study was carried out to test the hypothesis that elevated atmospheric CO2 (Ca) will alleviate over-excitation of the C4 photosynthetic apparatus and decrease non-photochemical quenching (NPQ) during periods of limited water availability. Chlorophyll a fluorescence was monitored in Sorghum bicolor plants grown under a free-air carbon-dioxide enrichment (FACE) by water-stress (Dry) experiment. Under Dry conditions elevated Ca increased the quantum yield of photosystem II ({\o}PSII) throughout the day through increases in both photochemical quenching coefficient (qp) and the efficiency with which absorbed quanta are transferred to open PSII reaction centres (Fv′/Fm′). However, in the well-watered plants (Wets) FACE enhanced {\o}PSII only at midday and was entirely attributed to changes in Fv′/Fm′. Under field conditions, decreases in {\o}PSII under Dry treatments and ambient Ca corresponded to increases in NPQ but the de-epoxidation state of the xanthophyll pool (DPS) showed no effects. Water-stress did not lead to long-term damage to the photosynthetic apparatus as indicated by {\o}PSII and carbon assimilation measured after removal of stress conditions. We conclude that elevated Ca enhances photochemical light energy usage in C4 photosynthesis during drought and/or midday conditions. Additionally, NPQ protects against photo-inhibition and photodamage. However, NPQ and the xanthophyll cycle were affected differently by elevated Ca and water-stress.",

keywords = "C photosynthesis, CO enrichment, Chlorophyll fluorescence, Water-stress, Xanthophyll cycle",

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T1 - Photosystem II energy use, non-photochemical quenching and the xanthophyll cycle in Sorghum bicolor grown under drought and free-air CO2 enrichment (FACE) conditions

AU - Cousins, A. B.

AU - Adam, N. R.

AU - Wall, G. W.

AU - Kimball, B. A.

AU - Pinter, P. J.

AU - Ottman, M. J.

AU - Leavitt, S. W.

AU - Webber, A. N.

PY - 2002/11

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N2 - The present study was carried out to test the hypothesis that elevated atmospheric CO2 (Ca) will alleviate over-excitation of the C4 photosynthetic apparatus and decrease non-photochemical quenching (NPQ) during periods of limited water availability. Chlorophyll a fluorescence was monitored in Sorghum bicolor plants grown under a free-air carbon-dioxide enrichment (FACE) by water-stress (Dry) experiment. Under Dry conditions elevated Ca increased the quantum yield of photosystem II (øPSII) throughout the day through increases in both photochemical quenching coefficient (qp) and the efficiency with which absorbed quanta are transferred to open PSII reaction centres (Fv′/Fm′). However, in the well-watered plants (Wets) FACE enhanced øPSII only at midday and was entirely attributed to changes in Fv′/Fm′. Under field conditions, decreases in øPSII under Dry treatments and ambient Ca corresponded to increases in NPQ but the de-epoxidation state of the xanthophyll pool (DPS) showed no effects. Water-stress did not lead to long-term damage to the photosynthetic apparatus as indicated by øPSII and carbon assimilation measured after removal of stress conditions. We conclude that elevated Ca enhances photochemical light energy usage in C4 photosynthesis during drought and/or midday conditions. Additionally, NPQ protects against photo-inhibition and photodamage. However, NPQ and the xanthophyll cycle were affected differently by elevated Ca and water-stress.

AB - The present study was carried out to test the hypothesis that elevated atmospheric CO2 (Ca) will alleviate over-excitation of the C4 photosynthetic apparatus and decrease non-photochemical quenching (NPQ) during periods of limited water availability. Chlorophyll a fluorescence was monitored in Sorghum bicolor plants grown under a free-air carbon-dioxide enrichment (FACE) by water-stress (Dry) experiment. Under Dry conditions elevated Ca increased the quantum yield of photosystem II (øPSII) throughout the day through increases in both photochemical quenching coefficient (qp) and the efficiency with which absorbed quanta are transferred to open PSII reaction centres (Fv′/Fm′). However, in the well-watered plants (Wets) FACE enhanced øPSII only at midday and was entirely attributed to changes in Fv′/Fm′. Under field conditions, decreases in øPSII under Dry treatments and ambient Ca corresponded to increases in NPQ but the de-epoxidation state of the xanthophyll pool (DPS) showed no effects. Water-stress did not lead to long-term damage to the photosynthetic apparatus as indicated by øPSII and carbon assimilation measured after removal of stress conditions. We conclude that elevated Ca enhances photochemical light energy usage in C4 photosynthesis during drought and/or midday conditions. Additionally, NPQ protects against photo-inhibition and photodamage. However, NPQ and the xanthophyll cycle were affected differently by elevated Ca and water-stress.

KW - C photosynthesis

KW - CO enrichment

KW - Chlorophyll fluorescence

KW - Water-stress

KW - Xanthophyll cycle

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