HPLC determination of photosynthetic pigments during greening of etiolated barley leaves. Evidence for the biosynthesis of chlorophyll a'.

The temporal evolution of pigment composition during greening of etiolated barley leaves was investigated by reversed-phase HPLC with particular attention to chlorophyll (Chl) a' (C13(2) epimer of Chl a), which had been detected by ourselves in photosystem (PS) I particles. At early stages of greening, the Chl a'/Chl a molar ratio rapidly increased to a level more than twice that in mature leaves, then gradually leveled off, accompanied by a growth of the Chl b/Chl a ratio, to the mature level. After 3 h of illumination, the temporal evolution of the Chl a'/Chl a molar ratio nearly paralleled that of the P700/Chl a ratio with a stoichiometry Chl a'/P700 approximately equal to 2: this strongly suggests that Chl a' is biosynthesized as a constituent of the PS I reaction center complex.