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KMID : 0368420040470020142
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Journal of Plant Biology
2004 Volume.47 No. 2 p.142 ~ p.148
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Reversible photoinactivation of photosystem II during desiccation of barley (Hordeum vulgare L. cv. Albori) leaves in the light
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Hwang Hong-Jin
Kim Eun-Mi
Rhew Tae-Hyong
Lee Choon-Hwan
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Abstract
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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.
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KEYWORD
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barley, chlorophyll fluorescence, desiccation, phosphatase inhibitor, photosystem II
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