90 



Fundamentals of Auxin Action 



struction of the indole ring also occurred. A different type of prod- 

 uct of auxin destruction has been proposed by Siegel and Weintraub 

 (1952), who found that auxins combine with peroxides to form some 

 complex which can then be restored to indoleacetic acid upon removal 

 of the peroxides by catalase or other reagents. Some evidence has been 

 advanced to indicate that peroxides may be formed as a product of 



_l 



UJ 



or 



< 

 < 



> The Indole Ring 



°^^ — ^ The Acid Group 



10 



TIME IN LIGHT 



15 



20 MIN. 



Fig. 45. Relative rates of disappearance of the indole ring (as determined by the 

 Hopkins-Cole Test) and the acid group (as determined by pH) of indoleacetic acid 

 during photo-destruction with riboflavin (Brauner, 1953). 



the enzymatic destruction of auxin (Andreae and Andreae, 1953). Thus 

 it appears that indolealdehyde is one product of auxin destruction, 

 though it may be further degraded, and perhaps even different path- 

 ways of destruction may be followed. 



Several materials can alter the enzymatic destruction of auxin. 

 For example, scopoletin, a naturally occurring lactone, is a competitive 

 inhibitor of the reaction (Andreae, 1952). Many compounds which can 



