Role of endogenous purine metabolism in thidiazuron-induced somatic embryogenesis of peanut (Arachis hypogaea L.)

Somatic embryogenesis was induced at the hypocotyledonary notch region of intact peanut (Arachis hypogaea L.) seedings cultured on a medium containing 10 mol·L^–1 thidiazuron (TDZ). Inclusion of the purine analogs 2,6-diaminopurine (DAP), azaadenine or azaguanine to the thidiazuron amended medium inhibited the embryogenic response of the seedlings. DAP-mediated inhibition was not overcome by the addition of adenine sulphate. Inhibition of the embryogenic response by DAP provides evidence that the TDZ-induced accumulation of purine cytokinins is an essential component of TDZ-induced somatic embryogenesis process. Analyses of the endogenous level of purine metabolites indicated that supplementation of the media with TDZ resulted in an overall increase in the endogenous cytokinins while DAP inhibited the purine recycling resulting in decreased levels of endogenous adenine and zeatin.