Role of Coumarins in Growth and Germination 745 



To elucidate the mode of its action, its effect on the metabolism 

 and enzymatic activity in germinating lettuce seeds has been investi- 

 gated. Various effects were observed, three of which seem to be prom- 

 ising in explaining the effect of coumarin: (a) The inhibition of 

 proteinase activity, which may disturb the normal enzymatic equili- 

 brium in the germinating seed; (b) the interference with phosphorus 

 metabolism which is liable to disturb the normal oxidative and en- 

 ergy transferring processes; and (c) there is much evidence to suggest 

 that coumarin has auxin-like activity and is closely concerned with 

 the metabolism of other growth regulating substances in the plant. 



It is likely that coumarin does not always act through all of these 

 mechanisms. In fact it seems probable that the difference in response 

 of different plants and plant tissues to coumarin is due to its affecting 

 different pathways, or affecting different rate-controlling steps in the 

 same pathway. In addition, the relative importance of the various 

 metabolic pathways probably differs between species, and, therefore, 

 a change in rate of the same step may be of varying significance in 

 different species or even organs. Moreover, the mode and extent of 

 coumarin metabolism probably differs in different plants. Much fur- 

 ther research is still needed to clarify the problem. 



LITERATURE CITED 



1. Aloni, R. The ATPase activity of lettuce mitochondria. M. Sc. Thesis, 20 pp., 

 Hebrew University, Jerusalem. (In Hebrew.) 1959. 



2. d'Amato, F., and d'Amato-Avanzi, M. G. The chromosome breaking effect of 

 coumarin derivatives in the Allium test. Caryologia. 6: 134-150. 1954. 



3. Andreae, W. A. Effect of scopoletin on indolacetic acid metabolism. Nature. 

 170: 83-84. 1952. 



4. Audus, L. J. Studies on the phytostatic action of 2:4-dichlorophenoxyacetic 

 acid and coumarin. The reversibility of root-growth inhibition. New Phytol. 

 47: 196-219. 1948. 



5. , and Quastel, J. H. Coumarin as a selective phytocidal agent. Nature. 



159: 320-324. 1947. 



6. Blumenthal-Goldschmidt, S. Growth substances metabolism in germinating let- 

 tuce seeds. Ph.D. Thesis, 100 pp., Hebrew University, Jerusalem. (In Hebrew.) 

 1959. 



7. Buis, R. Sur Taction de faibles concentrations de coumarine et d'hydrazide 

 maleique sur le tallage du Mais. Compt. Rend. Soc. Biol. 149: 2001-2003. 1955. 



8. Burr, G. O. Light, temperature and chemical factors affecting the flowering of 

 sugarcane. Proc. 8th Int. Bot. Congr. Section 11/12: 345-347. 1954. 



9. Burstrom, H. Studies on growth and metabolism of roots. XI. The influence of 

 auxin and coumarin derivatives on the cell wall. Physiol. Plant. 7: 548-559. 

 1954. 



10. Cook, A. H. (Address, 36th Ann. Gen. Meet, of Fellows.) Jour. Nat. Inst. 

 Agr. Bot. 8: 175-180. 1957. 



11. Cornman, I. Alteration of mitosis by coumarin and parasorbic acid. Amer. 

 Jour. Bot. 33: 217. (Abstr.) 1946. 



