Chlorina f2; Chlorophyll fluorescence; Hordeum vulgare; Light acclimation; Non-photochemical quenching; Photoprotection

Acclimation of the photosynthetic apparatus of chlorophyll b-less barley mutant chlorina f2 to low light (100 umol m-2 s-1; LL) and extremely high light level (1000 umol m-2 s-1; HL) was examined using techniques of pigment analysis and chlorophyll a fluorescence measurements at room temperature and at 77 K. The absence of chlorophyll b in LL-grown chlorina f2 resulted in the reduction of functional antenna size of both photosystem II (by 67%) and photosystem I (by 21%). Chlorophyll fluorescence characteristics of the LL-grown mutant indicated no impairment of the utilization of absorbed light energy in photosystem II photochemistry. Thermal dissipation of excitation energy estimated as nonphotochemical quenching of minimal fluorescence (SV0) was significantly higher as compared to the wild-type barley grown under LL. Despite impaired assembly of pigment-protein complexes, chlorina f2 was able to efficiently acclimate to HL.

Acclimation of the photosynthetic apparatus of chlorophyll b-less barley mutant chlorina f2 to low light (100 umol m-2 s-1; LL) and extremely high light level (1000 umol m-2 s-1; HL) was examined using techniques of pigment analysis and chlorophyll a fluorescence measurements at room temperature and at 77 K. The absence of chlorophyll b in LL-grown chlorina f2 resulted in the reduction of functional antenna size of both photosystem II (by 67%) and photosystem I (by 21%). Chlorophyll fluorescence characteristics of the LL-grown mutant indicated no impairment of the utilization of absorbed light energy in photosystem II photochemistry. Thermal dissipation of excitation energy estimated as nonphotochemical quenching of minimal fluorescence (SV0) was significantly higher as compared to the wild-type barley grown under LL. Despite impaired assembly of pigment-protein complexes, chlorina f2 was able to efficiently acclimate to HL.