The biogenesis of natural auxins 



the possibiUty of a pyruvate dehydrogenase mechanism has interesting 

 imphcations. 



In conchision, I hope I have left the impression that pathways of auxin 

 biosynthesis and interconversion are by no means clearly understood. 

 In a very real sense the work is just beginning, because we have only now 

 reached the stage of being able to define the problem. The field of auxin 

 anabolism merits a concerted attack — not only as a provocative problem in 

 biochemistry, but also as a physiological sequence functioning as a morpho- 

 genetic determinant. 



REFERENCES 



Gordon, S. A. (1954). Occurrence, formation, and inactivation of auxins. Anriu. 



Rev. PL Physiol. 5, 341. 

 Gordon, S. A. (1955). Studies on the mechanism of phytohormone damage by 



ionizing radiation. Proc. int. Conf. Atomic Energy, A/8/P/97, Geneva, Switzerland. 

 GuNSALUS, I. C. (1954). Oxidative and transfer reaction of lipoic acid. Fed. Proc. 13, 



715. 

 GuNSALUS, I. C., HoRECKER, B. L., and Wood, W. A. (1955). Pathways of carbo- 

 hydrate metabolism in microorganisms. Bact. Rev. 19, 79. 

 Jones, E. R. H., Henbest, H. B., Smith, G. F., and Bentley, J. A. (1952). 3-indolyl- 



acetonitrile: a naturally occurring plant growth hormone. Nature, 169, 485. 

 Krebs, H. a. (1936). Metabolism of amino acids and related substances. Annu. Rev. 



Biochem. 5, 247. 

 Leopold, A. C., and Guernsey, F. S. (1953). A theory of auxin action involving 



coenzyme A. Proc. Nat. Acad. Sci., Wash. 39, 1 105. 

 Reinert, J. (1954). Wachstum. Fortschr. Bot. 16, 330. 

 SiEGEL, S. M., and Galston, A. W. (1953). Experimental coupling of indoleacetic 



acid to pea root protein in vivo and in vitro. Proc. Nat. Acad. Sci., Wash. 39, 1111. 

 Skoog, F. (1937). A deseeded Avena test method for small amounts of auxin and 



auxin precursors. J. gen. Physiol. 20, 311. 

 Stowe, B., and Thimann, K. V. (1954). The paper chromatography of indole 



compounds and some indole-containing auxins of plant tissues. Arch. Biochem. 



Biophys. 51, 499. 

 Thimann, K. V. (1935). On the plant growth hormone produced by Rhizopus 



suinus. J. biol. Chem. 109, 279. 

 WiLDMAN, S. G., Ferri, M. G., and Bonner, J. (1947). The enzymatic conversion of 



tryptophan to auxin by spinach leaves. Arch. Biochem. 13, 131. 



75 



