PHOTOINHIBITION OF PHOTOSYNTHESIS WITHOUT NET LOSS OF PHOTOSYSTEM-II COMPONENTS IN POPULUS-DELTOIDES

The photoinhibition of photosynthesis was investigated on intact attac hed leaves and isolated thylakoid membranes of Populus deltoides, Our studies demonstrate that in intact leaves photoinhibition takes place under high irradiance which is more pronounced at higher temperatures, No net loss of D1 and other proteins associated sith photosystem II ( PSII) were observed even after 64% photoinhibition suggesting that the degradation of polypeptides associated, with PSII is not the only key step responsible for photoinhibition as observed by other workers, El ectron transport studies in isolated thylakoid membranes suggested wat er oxidation complex as one of the damaged site during high light expo sure, The possible mechanisms of photoinhibition without net loss of D 1 protein are discussed.