Hormones and hormone precursors 



Comparison of Figures 2{c), 2{e), and l{a) suggests that there is a growth 

 promoter at Rf 0- 1-0-2, which is probably being formed from another 

 substance, and the lack of the peak in Figure 2{a) is in agreement with this. 

 It is also possible that unstable compounds are involved, and small differences 

 in technique are influencing their reactions. 



Aqueous fraction of tomato roots 



The hormone content of ethereal extracts of excised and seedling roots is 

 low. Attention was therefore turned to the aqueous fraction, which, like that 

 of cabbage, showed high activity. 



130 g fresh weight of excised roots were extracted with ether and the 

 aqueous fraction prepared as in the cabbage experiments. Approximately 



^ 

 s 



/7 



76 







(a) 



//M 



I 1 



;/ 



HjO^c. 



HNO3/HNO2 



Me Yelloiv 



Response to lAA 



(rng/l.) 



0-2 



04 



0-e 



0-8 



1-0 



'f- 



Figure 3{a). Aqueous fraction of approximately \'i g excised tomato roots developed in ammoniacal 

 hopropanol. 



one-tenth of the aqueous fraction was chromatographed in /j^opropanol/ 

 ammonia. On initial chromatography separation was poor, so the chromato- 

 gram was eluted and redeveloped, when good separation was obtained. 

 The results show [Figure 3(a)) that there is considerable activity in the 

 aqueous fraction, with optimum stimulation at R^ 0-36 to 0-48 almost as 

 great as the 1 mg/1. lAA control. The u.v. fluorescence at the position of 

 optimum stimulation was deep purple tailing to pale blue. With 

 HNO2/HNO3 a pale yellow colour was obtained at R^ 0-36-0-54, but no 

 . colour appeared with FeCl3/HC104 or with /?-dimethvlaminobenzaldehvde 

 (MeAB). 



A further one-tenth of the aqueous fraction was chromatographed and 

 gave the same fluorescence as in the previous experiment. The zones of 

 Rf 0-32 to 0-76, corresponding to the stimulatory zone of the previous 

 experiment, were isolated, and re-eluted in a small quantity of water, which 

 was then reduced to 2 ml by distillation under reduced pressure. This 

 extract was chromatographed in /Vopropanol/ammonia, examined in u.v. 

 light and cut into 2-5 cm strips for bio-assay. The results are shown in 

 Figure 3{b). The greatest activity, in the region R^ 0-72 to 0-84, was almost 

 equal to that of 1-0 mg/1. lAA and corresponded in position with the IAN 

 control, though it could not be associated with any fluorescence. Clearly, 



45 



