ИСТИНА

Desiccation suppresses CO2-fixati CO2-fixation whereas photosynthetic electron transport from water to PS1 (ETC) is more resistant and possibly by this conditions oxygen may accept electrons in ETC. We investigated electron transport and Chl fluorescence induction in leaves of two wheat var. with different drought resistance. Under water stress the rate of fluorescence quenching decreased in drought-sensitive (DS) var. and increased in drought-resistant (DR) var. Simultaneously electron transport from PS2 to PS1 decreased only in DS var. Water stress increased oxygen reduction in PS1 of the DS var. whereas in the DR plants oxygen reduction increased in PS2. One can suggest that the electron flow to oxygen in PS2 prevents photoinhibition of DR var. Experiments with isolated PS2 membrane fragments supported it. It was showed that photoinhibition equally inhibited oxygen release and the oxygen reduction in PS2.