81 



PIGMENTS AND PHOTOSYNTHESIS 



Rol e of Pigments in Photosynthesis 



Green plants, particularly yoiing barley leaves, have been ex- 

 )d to a great variety of conditions that are known to affect the 

 osynthetic process,, The pigments were then extracted and sepa- 

 i by chromatographic adsorption in sugar columns ' ' '■'o Some 

 9 conditions employed were low temperature (-0°), high tempera= 

 '30-55°), carbon dioxide-free air, carbon dioxide-rich (5 per 

 air, vacu\jm, oxygen, reducing agents such as hydroquinone, 

 s, sunlight, and infrared and ultraviolet lighto Under all 

 .J aifferent conditions, the same pigments were always isolated, 

 and these pigments were obtained in about the same proportionso 



CONCLUSIONS 



The isolation of the ohloroplast pigments by chromatographic ad- 

 sorption methods has revealed characteristic pigment distributions 

 that facilitate the comparison and definition of the principal plant 

 groupso The occurrence of chlorophyll a, xanthophylls, and carotenes 

 in all plants that produce o::^gen by photosynthesis indicates a com^ < 

 mon origin for the photosynthetic apparatuSo It suggests a f\jnda= 

 mental functional role for the pigments that was established long > 

 before evolution of the species that are known today » 



The occurrence of specific chlorophylls and xanthophylls in 

 species of major taxonomic divisions supports the phylogeny or race 

 history of the principal plant groups. The occurrence of chlorophylls 

 a and b, lutein plus zeaxanthin, violaxanthin, neoxanthin, and (S=carotene 



