EXCITATION PRESSURE DEPENDENT DEVELOPMENT OF ALTERNATIVE NON-RADIATIVE CHARGE RECOMBINATION PATHWAYS IN WILD TYPE AND F2 MUTANT OF BARLEY

摘要

It has been demonstrated that the acclimation of higher plants, green algae and cyanobacteria to environmental conditions where the imbalance between energy supply and energy utilization occurs (low temperature or high light), is accompanied by development of higher reduction state of Q_A and higher resistance to photoinhibi-tion (Huner et al 1998). Although, this is a fundamental feature of all photoautotrophs (Huner et al 1998) and the acquisition of increased tolerance to photoinhibition has beenascribed to growth and development under high PSII excitation pressure, i.e., the ability to maintain higher reduction state of QA during steady state growth (Gray et al 1996, Huner et al 1998), the precise mechanism controlling the redox state of QA andits physiological significance in developing higher resistance to photoinhibition has not been fully elucidated. In this report we present evidence that the increased resistance to high light in plants acclimated to high excitation pressure conditions could be accounted for development of higher probability for alternative non-radiative energy dissipation pathway within the reaction center of PSII (Sane et al 2003, Ivanov et al 2003).