COMPARATIVE-STUDY OF RESPIRATORY METABOLISM IN 3 TYPES OF SUGAR-BEET CALLI, A NORMAL AND 2 HABITUATED ONES (ORGANOGENIC AND NON-ORGANOGENIC)

The respiratory metabolism was studied in three types of sugarbeet (Be ta vulgaris L. var, altissima) calli: a normal callus (N) and two full y habituated (auxin- and cytokinin-independent) calli, organogenic (HO ) and non-organogenic (HNO). Except for the HO callus at day 14, the o xygen consumption rates of the habituated calli were always higher tha n that of the normal callus throughout the cycle of culture. The maxim um activity of the cyanide-resistant pathway (alternative pathway) was much higher in the two habituated calli than in the normal one. By co ntrast, important differences were found in HNO and HO calli concernin g the activity of the cytochrome pathway. In HNO cells, the high activ ity of this pathway was correlated with a high ATP level while the inv erse situation was observed in HO cells. The physiological significanc e of these results is discussed. ((C) Academie des sciences / Elsevier , Paris.).