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- LEVERENZ, JW, et al.
(författare)
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PHOTOSYNTHESIS AND PHOTOINHIBITION IN LEAVES OF CHLOROPHYLL-B-LESS BARLEY IN RELATION TO ABSORBED LIGHT
- 1992
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 85:3, s. 495-502
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Tidskriftsartikel (refereegranskat)abstract
- The response of photosynthesis to absorbed light by intact leaves of wild-type (Hordeum vulgare L. cv. Gunilla) and chlorophyll b-less barley (H. vulgare L. cv. Dornaria, chlorina-f2(2800)) was measured in a light integrating sphere. Up to the section where the light response curve bends most sharply the responses of the b-less and wild-type barley were similar but not identical. Average quantum yield and convexity for the mutant light response curves were 0.89 and 0.90, respectively times those of the wild-type barley. The maximum quantum yield for PSII photochemistry was also 10% lower as indicated by fluorescence induction kinetics (F(v)/F(m)). Just above the region where the light curve bends most sharply, photosynthesis decreased with time in thc mutant but not in the wild-type barley. This decrease was associated with a decrease in F(v)/F(m) indicating photoinhibition of PSII. This photoinhibition occurred in the same region of the light response curve where zeaxanthin formation occurs. Zeaxanthin formation occurred in both the chlorophyll b-less and wild-type leaves. However, the epoxidation state was lower in the mutant than in the wild-type barley. The results indicate that chlorophyll b-less mutants will have reduced photosynthetic production as a result of an increased sensitivity to photoinhibition and possibly a lowered quantum yield and convexity in the absence of photoinhibition.
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| 2. |
- Wingsle, Gunnar, et al.
(författare)
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ISOLATION, PURIFICATION, AND SUBCELLULAR-LOCALIZATION OF ISOZYMES OF SUPEROXIDE-DISMUTASE FROM SCOTS PINE (PINUS-SYLVESTRIS L) NEEDLES
- 1991
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 95:1, s. 21-28
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Tidskriftsartikel (refereegranskat)abstract
- Two of four isozymes of superoxide dismutase (SOD) (EC 1.15.1.1) were purified from Scots pine (Pinus sylvestris L.) needles. One form was cytosolic (SOD-1) and the other was associated with chloroplasts (SOD-3). The holoenzyme molecular masses was estimated at approximately 35 kilodaltons by gel filtration. The subunit molecular weight of the dimeric enzymes was estimated to 16.5 kilodaltons (SOD-1) and 20.4 kilodaltons (SOD-3) on sodium dodecyl sulfatepolyacrylamide gels. The NH2-terminal sequence of the pine enzymes showed similarities to other purified superoxide dismutases located in the corresponding compartment. The cytosolic form revealed two additional amino acids at position 1 and 2 at the NH2-terminal. Both forms were cyanide- and hydrogenperoxide-sensitive and SOD-3 was found to contain approximately one copper atom per subunit, indicating that they belong to the cupro-zinc SODs. The isoelectric point was 4.9 and 4.5 for SOD-1 and SOD-3, respectively.
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