CHANGES IN RESPONSE TO PURINE AND PYRIMIDINE DERIVATIVES OF CARROT ROOT CALLUS DURING SUCCESSIVE CULTURING

1. The growth of the carrot root callus which had been subculturedfor a long period (CCL) was promoted by the addition of 5l0^–8and 5l0^–7 M kinetin, whereas in the callus subculturedfor a short period (CCS) no growth promotion was observed atany concentrations of kinetin tested.
2. CCL showed an increasedgrowth in response to the applicationof kinetin, guanine, adenine,hypoxanthine, uracil, thymine,and cytosine in the presenceof fractions A and C of carrotroot extract, whereas no suchresponse was observed in CCS.CCL required fraction C to respondto uracil and probably purineand pyrimidine derivatives ingeneral.
3. The growth of CCL was promoted by kinetin, guanine,adenine,or hypoxanthine in the medium containing inositol andaminoacids mixture. In this case the growth-promoting actionof guanine,adenine, or hypoxanthine was nullified by kinetin.

(Received December 24, 1964; )