TY - JOUR
T1 - Photosynthetic electron transport and specific photoprotective responses in wheat leaves under drought stress
AU - Zivcak, Marek
AU - Brestic, Marian
AU - Balatova, Zuzana
AU - Drevenakova, Petra
AU - Olsovska, Katarina
AU - Kalaji, Hazem M.
AU - Yang, Xinghong
AU - Allakhverdiev, Suleyman I.
N1 - Funding Information:
Alagoas, Prac¸a Afrânio Jorge, s/n, Prado, Maceió, AL, Brazil) for reviewing and improving the English of the manuscript. The research described here has been supported by grant APVV-0197-10 and APVV-0661-10. This study was also supported by grants from the Russian Foundation for Basic Research and Molecular and Cell Biology Programs of the Russian Academy of Sciences to SIA.
Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/11
Y1 - 2013/11
N2 - The photosynthetic responses of wheat (Triticum aestivum L.) leaves to different levels of drought stress were analyzed in potted plants cultivated in growth chamber under moderate light. Low-to-medium drought stress was induced by limiting irrigation, maintaining 20 % of soil water holding capacity for 14 days followed by 3 days without water supply to induce severe stress. Measurements of CO2 exchange and photosystem II (PSII) yield (by chlorophyll fluorescence) were followed by simultaneous measurements of yield of PSI (by P700 absorbance changes) and that of PSII. Drought stress gradually decreased PSII electron transport, but the capacity for nonphotochemical quenching increased more slowly until there was a large decrease in leaf relative water content (where the photosynthetic rate had decreased by half or more). We identified a substantial part of PSII electron transport, which was not used by carbon assimilation or by photorespiration, which clearly indicates activities of alternative electron sinks. Decreasing the fraction of light absorbed by PSII and increasing the fraction absorbed by PSI with increasing drought stress (rather than assuming equal absorption by the two photosystems) support a proposed function of PSI cyclic electron flow to generate a proton-motive force to activate nonphotochemical dissipation of energy, and it is consistent with the observed accumulation of oxidized P700 which causes a decrease in PSI electron acceptors. Our results support the roles of alternative electron sinks (either from PSII or PSI) and cyclic electron flow in photoprotection of PSII and PSI in drought stress conditions. In future studies on plant stress, analyses of the partitioning of absorbed energy between photosystems are needed for interpreting flux through linear electron flow, PSI cyclic electron flow, along with alternative electron sinks.
AB - The photosynthetic responses of wheat (Triticum aestivum L.) leaves to different levels of drought stress were analyzed in potted plants cultivated in growth chamber under moderate light. Low-to-medium drought stress was induced by limiting irrigation, maintaining 20 % of soil water holding capacity for 14 days followed by 3 days without water supply to induce severe stress. Measurements of CO2 exchange and photosystem II (PSII) yield (by chlorophyll fluorescence) were followed by simultaneous measurements of yield of PSI (by P700 absorbance changes) and that of PSII. Drought stress gradually decreased PSII electron transport, but the capacity for nonphotochemical quenching increased more slowly until there was a large decrease in leaf relative water content (where the photosynthetic rate had decreased by half or more). We identified a substantial part of PSII electron transport, which was not used by carbon assimilation or by photorespiration, which clearly indicates activities of alternative electron sinks. Decreasing the fraction of light absorbed by PSII and increasing the fraction absorbed by PSI with increasing drought stress (rather than assuming equal absorption by the two photosystems) support a proposed function of PSI cyclic electron flow to generate a proton-motive force to activate nonphotochemical dissipation of energy, and it is consistent with the observed accumulation of oxidized P700 which causes a decrease in PSI electron acceptors. Our results support the roles of alternative electron sinks (either from PSII or PSI) and cyclic electron flow in photoprotection of PSII and PSI in drought stress conditions. In future studies on plant stress, analyses of the partitioning of absorbed energy between photosystems are needed for interpreting flux through linear electron flow, PSI cyclic electron flow, along with alternative electron sinks.
KW - Alternative electron sinks
KW - Chlorophyll fluorescence
KW - Cyclic electron transport around PSI
KW - Drought stress
KW - Photosynthetic electron transport
KW - Photosystem stoichiometry
KW - Wheat
UR - http://www.scopus.com/inward/record.url?scp=84888883260&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84888883260&partnerID=8YFLogxK
U2 - 10.1007/s11120-013-9885-3
DO - 10.1007/s11120-013-9885-3
M3 - Article
C2 - 23860828
AN - SCOPUS:84888883260
VL - 117
SP - 529
EP - 546
JO - Photosynthesis Research
JF - Photosynthesis Research
SN - 0166-8595
IS - 1-3
ER -