carotenoids in plants 



Formation 



The possible relationship between chlorophyll and carotenoid 

 formation in the higher plants has been discussed in the previous 

 chapter. This possibility is ruled out in dealing with fungi which are 

 characterized by the absence of chlorophylls. 



In Rhodotorula rubra a typical pattern of pigmentation was noted 

 which could be divided into three distinct phases : {a) a period of 

 active synthesis leading to maximal carotenoid concentration ; (b) a 

 period of persistence when no changes take place and finally (c) a 

 period during which the pigmentation gradually disappears. Pigment 

 formation is stimulated and the onset of the third phase delayed 

 indefinitely when oleic acid is added to the medium ; on the other hand, 

 the addition of ammonium sulphoricinoleate inhibits carotenogenesis 

 and accelerates the appearance of the third phase. * «. * ' 



Garton et al. ^ *• ^ « have noted the same general pattern in Phyco- 

 myces blakesleeanus but found that the first phase, that of active 



I3C 



120 



90 



60 



30 



3 4 5 6 



Age of culcure (days) 



10 



Fig. 18. — The rate of carotene synthesis in Phycomyces blakesleeanus, compared 

 with growth (dry wt. production and nitrogen assimilation). {From 

 Goodwin, T. W., and Willmer, J. S. (1952) Biochen, J., in the press.) 



^. ---# p-Carotene. 



O O Dry wt. production. 



# • Nitrogen assimilation. 



109 



