Polyamines and Somatic Embryogenesis in Carrot. III. Effects of Methylglyoxal bis(guanylhydrazone)l

The effects of methylglyoxal bis(guanylhydrazone) (MGBG) on somatic embryogenesis, titres of cellular polyamines and 1-aminocyclopropane-l-carboxylic acid, and the activity of arginine decarboxylase (ADC) were studied using suspension cultures of carrot (Daucus carota L.). Whereas MGBG (0.1–0.5 mM) significantly inhibited the cellular levels of spermidine and spermine, putrescine levels were higher in the treated tissue. MGBG also promoted ACC levels in the cells. The activity of ADC was inhibited in the presence of MGBG. Somatic embryogenesis in the auxin-free medium was completely inhibited by MGBG. The effects of MGBG on somatic embryogenesis were reversed by 0.1–0.2 mM spermidine but not by spermine. These results are consistent with the suggestion that an interaction between ethylene and polyamine bio-synthetic pathways through competition for the common precursor, S-adenosylmethionine, plays an important role in the development of somatic embryos in carrot cell cultures.