Metabolism and mode of action 



than the aerial portions of the plant, have a tenfold higher oxidase activity 

 than stems. Secondly, in both roots and stems, it is true that young, actively 

 growing regions are very low in oxidase activity, while progressively older 

 and older regions have successively higher and higher oxidase activity 

 {Figure 7) . This suggested that destruction of auxin by the oxidase system is 

 actually a growth-regulatory mechanism. 



Specific activities 

 (ylAA desfpoyec//m.q profe/nH/yir) 



230 



en- 



1V-10- 



1518- 



21-eo- 



301 S- 



*t 



285 



-17 fO 



t 2375 



Figure 7. The distribution of lAA oxidase 

 activity in various portions of the etiolated pea 

 epicotyl. Bud data are on the right, stem data on 

 the left. Root values (not shown) range from 

 2000 at the apex to 4000 about 2 cm back. 



f5 



1-0 



35 





-^25 

 ^ZO 

 ^15 



10 



Per ZOO inq F.W. 

 Per 0-1 Tag protein N 







_L 



O't 



% 



V 



0-3 



\ 



0-2 



E 

 ^0-1 



■-- Per ZOO TTig /:W 



• Per 0-1 Tug protein N 



3 e s iz 



Distance from the tip 



15 18 



TTUTl 



3 e S IZ 15 18 

 Distance from tfie tip hitti 



Figures 8. 9. The distribution of lA.A-oxidase activity {Figure 8) and peroxide generating capacity 

 {Figure 9) in successive 3 mm sections of the primary root o/Lens culinaris. 



226 



