Anti-sense RNA efficiently inhibits formation of the 10 kd polypeptide of photosystem II in transgenic potato plants: analysis of the role of the 10 kd protein.

A chimeric gene encoding an anti-sense RNA of the 10 kd protein of the water-splitting apparatus of photosystem II of higher plants under the control of the CaMV 35S promoter was introduced into potato using Agrobacterium based vectors. The expression of the anti-sense RNA led to a significant reduction of the amounts of the 10 kd protein and RNA in a number of transgenic plants. In three out of 36 plants tested, the level of the 10 kd protein was only up to 1-3% compared with the wild-type control. The drastic reduction of the 10 kd protein did not influence the accumulation of other photosystem II associated polypeptides at both the RNA and protein level. Furthermore no phenotypic differences were observed between potato plants expressing wild-type and drastically reduced levels of the 10 kd protein with respect to growth rate, habitus or ultrastructure of the chloroplasts. Measurements of the relaxation of the flash-induced enhancement in the fluorescence quantum yield as determined in intact leaves and the rates and characteristic oscillation pattern of O2 evolution as determined in isolated thylakoid samples however, show that the elimination of the 10 kd protein on the one hand retards reoxidation of QA- and on the other hand introduces a general disorder into the PSII complex.