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Reversible photoinactivation of photosystem II during desiccation of barley (Hordeum vulgare L. cv. Albori) leaves in the light

한국식물학회지 2004년 47권 2호 p.142 ~ 148
 ( Hwang Hong-Jin ) - Pusan National University Department of Molecular Biology

 ( Kim Eun-Mi ) - Pusan National University Department of Biology
 ( Rhew Tae-Hyong ) - Pusan National University Department of Biology
이춘환 ( Lee Choon-Hwan ) - Pusan National University Department of Molecular Biology

Abstract


We investigated the inherent protective mechanisms against stress and damage to photosystem II (PSII) in barley (Hordeum vulgare L. cv. Albori). Leaves were desiccated at 30% relative humidity, under either low or high light (photon flux densities of 100 or 300 μmol m-2 s-1, respectively). During the treatment period, relative water content dropped to 35 to 45%, depending on light intensity. However, the photochemical efficiency of PSII (Fv/Fm) decreased only about 10%. This relatively stable response was due to the rapid, reversible increase in Fm (maximum fluorescence) during 20 min of dark-adaptation. During desiccation in the light, however, PSII was photo-inactivated by non-photochemical quenching (NPQ), with the excess excitation energy absorbed by the chlorophyll being dissipated as heat energy. This decline in NPQ in the first 2 min of treatment was caused by a relaxation in the energy-dependent quenching during dark-adaptation, but could be delayed significantly by a phosphatase inhibitor, NaF. In addition, the relaxation of other NPQ components related to state transition and phosphorylation of thylakoid phosphoproteins were blocked by NaF.

키워드

barley; chlorophyll fluorescence; desiccation; phosphatase inhibitor; photosystem II
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