lAA OXIDASE INHIBITOR AND MORPHOGENESIS 139 



This lAA oxidase inhibitor is water soluble, heat stable, and dialyza- 

 ble, and, on the basis of yet incomplete evidence, is considered to be 

 a phenol. 



From the heterogeneous nature of these effects, it is clear that any 

 attempt to generalize is at present ill-advised. Investigation of any one 

 of the effects could be expected to yield interesting information on the 

 biochemistry of photomorphogenesis. For several years, we have been 

 concerned with the relation between the photomorphogenic reaction 

 and auxin metabolism. It is for this reason that we have concentrated 

 on the last-described phenomenon. We have currently in progress in- 

 vestigations of the chemical nature of the inhibitor, its distribution in 

 the plant, and the effect of environmental and chemical treatments on 

 its level. In all these experiments, we assay for this substance by its 

 inhibition of indoleacetic acid destruction. However, we wish to make 

 it clear that we are in no sense committed to the thesis that the action 

 of this substance in vivo is, in fact, connected with auxin destruction. 

 So far as we are now concerned, the inhibitor has great intrinsic inter- 

 est because its production seems so directly connected with the red-far 

 red reaction, and the lAA-oxidase system is merely a handy tool for 

 the assay of this unknown substance. By the same token, we in no way 

 wish to rule out the possibility that the inhibitor does, in fact, affect 

 growth by sparing auxin from destruction. 



It is thus our belief that further knowledge of this substance whose 

 synthesis is controlled by the reversible photoreaction will help eluci- 

 date the details of photomorphogenesis. This paper will therefore pre- 

 sent previously unpublished information on its distribution in the green 

 pea plant, its rise and fall in response to physical and chemical stimuli, 

 and some details concerning its chemical nature. 



DISTRIBUTION OF INDOLEACETIC ACID OXIDASE AND ITS 

 INHIBITOR IN LIGHT-GROWN PEAS 



Materials and Methods 



The experimental organisms in these studies were seedlings of light- 

 grown Alaska and Laurel (dwarf) peas (Pisum sativum L.) purchased 

 from Associated Seed Growers, New Haven, Connecticut. The seeds 

 were soaked in tap water for 2 hr, and were then sown in coarse Zono- 



