[Photochemical activity of pea mutants with damaged photosystems].

The interrelationship between biochemical photosynthetic reactions and mutations was investigated, using five nuclear recessive lethal pea mutants with damaged photosystems II (1, 19) and I (5, 21, 22). Based on the data from photoreduction of NADP+, light-induced redox conversions of exogenous and endogenous plastocyanines in isolated chloroplasts, light-induced redox conversions of cytochrome f and absorbance changes at 520 nm in chloroplasts and leaves, the possible existence of alternative pathways of electron transfer and the pleiotropic effects of mutations, are discussed. A correlation between the structural damages of chloroplasts and the photochemical activity of mutants was found. The existence of cyclic electron transport around photosystem I involving cytochrome f and plastocyanine in mutants 1 and 19 and of an electron transfer pathway from H2O to NADP+ without plastocyanine in mutant 22 is postulated.