SECRETION OF AMYLASE BY PLANT ROOTS' 



L. Knudson and R. S. Smith 



(with two figures) 



The fact that green plants are able to absorb certain organic 

 substances by means of the roots, and to utilize these substances, 

 suggests the question whether the roots of plants secrete enzymes 

 in a manner comparable to various fungi, digesting in the culture 

 medium, etc., the various organic substances that might be sup- 

 plied. Various investigators have incidentally touched the subject, 

 but the evidence obtained is conflicting and not at all conclusive. 



Laurent (3) reported the inversion of saccharose when this 

 sugar was present in the culture media, and he ascribed this to 

 the enzyme invertase secreted by the roots of corn or of peas. 

 Starch was Hkewise transformed, but Laurent ascribed this trans- 

 formation to diastase secreted by the seed. Maze (4) reported 

 inversion of saccharose, but in 191 1 (5) he stated that there was 

 no enzyme secretion by the roots, and that starch was absorbed 

 directly' Wohllebe (8), investigating the secretion of amylase 

 by roots, came to the conclusion that there was a very weak 

 secretion of amylase by the root hairs, and in some cases secretion 

 of amylase was effected by the disconnected root-cap cells. The 

 senior writer of this paper suggested in a previous publication (2) 

 that invertase is secreted by the roots. 



In view of the indefiniteness of information on the subject, it 

 seemed advisable to investigate the problem. The first experi- 

 ments were made on the secretion of amylase, and the results 

 obtained constitute the basis for this paper. 



Pfeffer's was the nutrient solution employed. It was made up 

 according to the following formula: Ca(N03)2 4 gm., KNO3 i gm., 

 K,HP04 I gm., MgS04 i gm., KCl 0.5 gm., FeClj 100 mg., 

 distilled water 6 1. Merck's soluble starch was used throughout 

 the experiments. 



' Contribution from the Laboratory of Plant Physiology, Cornell University. 

 Botanical Gazette, vol. 68] [460 



