| Popis: |
Plants exposed to intense illumination undergo an inhibition of photosynthesis in a process called photoinhibition. Early studies of photoinhibition, using chloroplasts and monochromatic light, identified two spectral ranges of photoinhibitory light, which gave rise to somewhat different effects (1–4). The action spectrum showed a UV light effect, mainly in the UV-B range, and a visible light effect. The quantum yield in the UV range was about a hundredfold greater than that in the visible range, which had the action spectrum of photosynthetic pigments. The UV-photoinhibition was specifically related to PS II. Some controversy exists as to whether the locus of UV-photoinhibition lies on the donor (1–9) or acceptor (10–12) side of PS II. It has also been suggested that in plants, the action spectrum of UV photoinhibition may reflect DNA damage (13). This work represents an attempt to further clarify the mechanism of UV-photoinhibiton of PS II in isolated PS II preparations, chloroplasts and intact plants. |
