Is electron transport to oxygen an important mechanism in photoprotection? Contrasting responses from Antarctic vascular plants

摘要: Photoreduction of oxygen by the photosynthetic electron transport chain has been suggested to be an important process in protecting leaves from excess light under conditions stress; however, there is little evidence that this occurs significantly except when plants are exposed outside their normal tolerance range. We have examined dependency two vascular found growing Antarctica - Colobanthus quitensis and Deschampsia antarctica. Photosynthetic C. insensitive changes concentration non-photorespiratory conditions, indicating negligible; it a substantial capacity for non-photochemical quenching (NPQ) chlorophyll fluorescence. In contrast, D. antarctica up 30% its being linked oxygen, but substantially lower NPQ. Thus, these rely on contrasting photoprotective mechanisms cope with Antarctic environment. Both seem use cyclic flow associated PSI, activated at irradiance than