Wah Soon Chow

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We propose a simplified alternative method for quantifying the partitioning of excitation energy between photochemistry, fluorescence and thermal dissipation. This alternative technique uses existing well-defined quantum efficiencies such as ΦPS II, leaving no 'excess' efficiency unaccounted for, effectively separates regulated and constitutive thermal(More)
Dynamic acclimation of the photosynthetic apparatus in response to environmental cues, particularly light quantity and quality, is a widely-observed and important phenomenon which contributes to the tolerance of plants against stress and helps to maintain, as far as possible, optimal photosynthetic efficiency and resource utilization. This mini-review(More)
The literature and our present examinations indicate that the intra-leaf light absorption profile is in most cases steeper than the photosynthetic capacity profile. In strong white light, therefore, the quantum yield of photosynthesis would be lower in the upper chloroplasts, located near the illuminated surface, than that in the lower chloroplasts. Because(More)
When light absorption by a plant exceeds its capacity for light utilization, photosynthetic light harvesting is rapidly downregulated by photoprotective thermal dissipation, which is measured as nonphotochemical quenching of chlorophyll fluorescence (NPQ). To address the involvement of specific xanthophyll pigments in NPQ, we have analyzed mutants affecting(More)
Leaf discs of the shade plant Tradescantia albiflora Kunth grown at 50 μmol · m−2 · s−1, and the facultative sun/shade plant Pisum sativum L. grown at 50 or 300 μmol · m−2, s−1, were photoinhibited for 4 h in 1700 μmol photons m−2 · s−1 at 22° C. The effects of photoinhibition on the following parameters were studied: i) photosystem II (PSII) function; ii)(More)
The obligate shade plant, Tradescantia albiflora Kunth grown at 50 μmol photons · m−2 s−1 and Pisum sativum L. acclimated to two photon fluence rates, 50 and 300 μmol · m−2 · s−1, were exposed to photoinhibitory light conditions of 1700 μmol · m−2 · s−1 for 4 h at 22° C. Photosynthesis was assayed by measurement of CO2-saturated O2 evolution, and(More)
The formation of grana in chloroplasts of higher plants is examined in terms of the subtle interplay of physicochemical forces of attraction and repulsion. The attractive forces between two adjacent membranes comprise (1) van der Waals attraction that depends on the abundance and type of atoms in each membrane, on the distance between the membranes and on(More)
The multiple roles of light-harvesting chlorophyll a/b-protein complexes in the structure and function of Arabidopsis chloroplasts were investigated using two chlorophyll b-less mutants grown under metal halide lamps with a significant far-red component. In ch1-3, all six light-harvesting proteins of photosystem (PS) II were greatly decreased; in(More)
The efficiency of photosynthetic electron transport depends on the coordinated interaction of photosystem II (PSII) and photosystem I (PSI) in the electron-transport chain. Each photosystem contains distinct pigment-protein complexes that harvest light from different regions of the visible spectrum. The light energy is utilized in an endergonic(More)
Leaf segments from Capsicum annuum plants grown at 100 μmol photons  m−2 s−1 (low light) or 500 μmol photons  m−2 s−1 (high light) were illuminated at three irradiances and three temperatures for several hours. At various times, the remaining fraction (f) of functional photosystem II (PS II) complexes was measured by a chlorophyll fluorescence parameter(More)