Two patterns of leaf photosynthetic response to irradiance transition from saturating to limiting one in some plant species
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- • Plants often regulate the amount and size of light-harvesting antenna (LHCII) to maximize photosynthesis at low light and avoid photodamage at high light.
- • Gas exchange, 77 K chlorophyll fluorescence, photosystem II (PSII) electron transport as well as LHCII protein were measured in leaves irradiated at different light intensities.
- • After irradiance transition from saturating to limiting one leaf photosynthetic rate in some species such as soybean and rice declined first to a low level, then increased slowly to a stable value (V pattern), while in other species such as wheat and pumpkin it dropped immediately to a stable value (L pattern). Saturating pre-irradiation led to significant declines of both 77 K fluorescence parameter F685/F735 and light-limited PSII electron transport rate in soybean but not in wheat leaves, indicating that some LHCIIs dissociate from PSII in soybean but not in wheat leaves.
- • The L pattern of LHCII-decreased rice mutant and the V pattern of its wild type demonstrate that the V pattern is linked to dissociation/reassociation of some LHCIIs from/to PSII.