THE DISTRIBUTION OF NATURAL HORMONES IN 

 GERMINATING SEEDS AND SEEDLING PLANTSj 



Phyllis M. Cartwright:]:, J. T. Sykes, and R. L, Wain 



Wye College, University of London 



Many investigators have reported on the occurrence of auxins and inhibitors 

 in seeds. Germination inhibitors or 'blastocholines' are of widespread 

 occurrence in fruits and seeds, and seem to be important in those which 

 require special environmental conditions for germination. 



The purpose of the present investigation was to identify the natural 

 auxins and inhibitors in maize and pea seeds and to follow their changes in 

 concentration and distribution during germination and subsequent seedUng 

 growth. It was hoped that by using paper chromatography all the active 

 components could be isolated and their concentrations estimated by bio- 

 logical and perhaps by chemical methods. Ether extracts were made from 

 seeds at different stages of germination and these extracts were separated into 

 acid and non-acid fractions by a method developed from that of Boysen- 

 Jensen (1941). The components of the acid fraction were isolated by paper 

 chromatography and identified by biological assay and chemical colour 

 reactions. The non-acid fractions, prepared by a variety of methods, always 

 contained large amounts of oily substances which interfered with the chroma- 

 tography. Those examined gave unsatisfactory results and little biological 

 activity was found, though in each case all regions of the paper were assayed. 



The importance of obtaining a comprehensive picture of hormone and 

 inhibitor status in plant tissues is, of course, recognized, and has been stressed 

 by a number of workers. However, the quantitative estimation of such 

 activity in the neutral fraction of tissue extracts has not been successfuUy 

 accomplished here or elsewhere. Because of these limitations, only the 

 results from acid fractions will be considered in this paper, and in adopting 

 this procedure the work is in line with similar investigations on natural 

 auxins carried out by other workers. It will be realized that any hormones 

 of a non-acidic nature, such as indolylacetonitrile, would be present mainly 

 in the non-acid fractions. 



In carrying out the experiments, large numbers of seeds were germinated 

 under uniform conditions, samples taken at suitable intervals of time, and 

 their auxin and inhibitor content estimated. For the extraction procedure, 

 the seeds were cut into slices and extracted at 2°C with 3 changes of wet 

 peroxide-free ether for a total period of 24 hours. It is agreed with other 

 workers that this does not give a maximum yield of auxin, and with maize, for 

 example, further small amounts have been obtained by prolonged extrac- 

 tions for 2 weeks. However, since the largest part of the auxin is extracted in 

 the first 24 hours, it was decided to limit the analysis to this fraction in the 

 first instance. For separation of acidic and non-acidic fractions, a technique 



t This paper was read at the conference by Phyllis M. Cartwright. 



+ Present address: Department of Agricultural Botany, University of Reading. 



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