Regular Paper

Photosynthesis Research

, Volume 117, Issue 1, pp 529-546

First online:

Photosynthetic electron transport and specific photoprotective responses in wheat leaves under drought stress

  • Marek ZivcakAffiliated withDepartment of Plant Physiology, Slovak Agricultural University
  • , Marian BresticAffiliated withDepartment of Plant Physiology, Slovak Agricultural University Email author 
  • , Zuzana BalatovaAffiliated withDepartment of Plant Physiology, Slovak Agricultural University
  • , Petra DrevenakovaAffiliated withDepartment of Plant Physiology, Slovak Agricultural University
  • , Katarina OlsovskaAffiliated withDepartment of Plant Physiology, Slovak Agricultural University
  • , Hazem M. KalajiAffiliated withDepartment of Plant Physiology, Faculty of Agriculture and Biology, Warsaw Agricultural University SGGW
  • , Xinghong YangAffiliated withState Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University
  • , Suleyman I. AllakhverdievAffiliated withInstitute of Plant Physiology, Russian Academy of SciencesInstitute of Basic Biological Problems, Russian Academy of Sciences

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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.


Drought stress Wheat Photosynthetic electron transport Cyclic electron transport around PSI Photosystem stoichiometry Chlorophyll fluorescence Alternative electron sinks