In this thesis, the effect of stress, trough drought and high light intensity, on the expression of D1 subunit of photosystem II, the PsbO subunit of the oxygen-evolving complex (OEC), and the large subunit (LSU) of the Rubisco enzyme in barley (Hordeum vulgare L.) cultivar Panonac was investigated. e. Barley seedlings were exposed to 14 days of drought stress and to high light intensity stress in the climate chamber in duration of 4 and 11 hours. To determine the amount of examined photosynthetic proteins, denaturing polyacrylamide gel electrophoresis (SDS-PAGE) was used for their separation followed by the transfer to a nitrocellulose membrane (Western blot) and detection with specific antibodies. Exposure to drought induced stress did not result in significant degradation of any of three examined photosynthetic proteins. Exposure to stress caused by high light intensity showed stronger degradation compared to drought exposure in all three proteins. Shorter exposure to high light intensity (4h) caused more degradation of the D1 and LSU subunits when compared to a longer exposure (11h) to this type of stress. The results obtained indicate that the selected cultivar of barley showed a lower sensitivity to drought compared to the high light intensity stress.