FUNCTION OF CAROTENOIDS IN PHANEROGAMS 



important differences in the glucosides present in the pollens. R° pollen 

 contains quercitrin, whilst R+ pollen contains rutin. 



.OH 





 Quercitrin 



Moewus 2 ^ ^ has developed the biological aspect of this problem 

 and reports that rutin and quercitrin are pollination inhibitors. Cross- 

 fertilization is effective because pollen from long-styled flowers con- 

 tains a quercitrin splitting enzyme and the short-styled pollen a 

 rutin-splitting enzyme ; cross-pollination allows fertilization by 

 hydrolyzing the pollination inhibitors. The inhibition caused by 

 rutin and quercitrin can be destroyed by H3BO4, when the two types 

 of Forsythia become self-fertile. Confirmation of this novel report is 

 eagerly awaited. 



Recently, Schwartzenbach ^ ^ ^^ has described a technique for measur- 

 ing the effect of various carotenoids on the pollination of Cyclamen 

 persicum. The carotenoids examined fell into three groups : those 

 which stimulated, those which retarded and those which had no effect 

 on pollination. A consideration of these results reveals that each group 

 contains a heterogeneous collection of carotenoids and that no structural 

 criterion of activity emerges from this study. 



DESTRUCTION OF CAROTENOIDS IN PLANTS 



The well known fact that a preliminary blanching of harvested plant 

 materials prevents oxidation of carotenoids indicates that the process is 

 enzymic in nature. Similar oxidations have been achieved photo- 

 chemically, and it is difficult to say finally whether in vivo two separate 

 processes occur or whether light plays a part in a fundamental enzymic 

 process. Bernstein and Thompson 2\* consider that two separate 

 processes occur. 



(A) The Photochemical Process. In 1933 Meyer 21' found that 

 chlorophyll was an activating agent in the photochemical destruction 

 of (inter alia) lycopene. There the matter rested for 10 years until in 

 1943 Pepkowitz^is made an important contribution to this aspect of 



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