Temperature sensitivity of photosystem II in isolated thylakoid membranes from furidone-treated pea leaves

Abstract

High temperature-induced changes in the photosystem II (PSII) activity of thylakoid membranes isolated from pea (Pisumsativum L. Ran ) plants treated with low (10 8 M) and high (10 7 M) concentrations of furidone were investigated. Pulse amplitudemodulated (PAM) chlorophyll fuorescence and photosynthetic oxygen evolution (measured by polarographic oxygen rate electrode)were used to estimate the efect of high temperature on the functional activity of PSII. Higher temperature treatments lead to strongerinhibition of the fash oxygen evolution than the primary photochemistry of PSII (F v/F m). Te inhibitory efect of higher temperature onthe PSIIα centers is stronger than on the PSIIβ centers. Te heat-induced damage in the PSIIα centers as well as in the donor side of allPSII centers (PSIIα and PSIIβ) is accentuated by furidone.