Reversible photoinactivation of photosystem II during desiccation of barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L. cv. Albori) leaves in the light |
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Authors: | Hong?Jin?Hwang Eun?Mi?Kim Tae?Hyong?Rhew Email author" target="_blank">Choon-Hwan?LeeEmail author |
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Institution: | (1) Department of Molecular Biology, Pusan National University, 609-735 Busan, Korea;(2) Department of Biology, Pusan National University, 609-735 Busan, Korea |
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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. |
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Keywords: | barley chlorophyll fluorescence desiccation phosphatase inhibitor photosystem II |
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