ACTIVITIES OF MITOCHONDRIA ISOLATED DURING SOMATIC EMBRYOGENESIS OF ABIES ALBA MILLER

Some activities of mitochondria, isolated from an embryogenic cell line of Abies alba, during proliferation and maturation stages of somatic embryogenesis (SE), were studied. After the transfer of A. alba embryogenic cell masses (ECMs) from proliferation to maturation media, an increase in cellular ATP and glucose-6-phosphate content was observed. Mitochondria obtained from ECMs during proliferation showed a low activity of alternative pathways, such as the alternative oxidase (AO) and external NADH dehydrogenases, and a high level of potassium fluxes mediated by the K+ ATP channel. Conversely, when the same parameters were evaluated in mitochondria isolated from ECMs, after 6 and 9 week lasting maturation, a different pattern was observed. In fact, the oxidation of exogenous NADH, the AO capacity and expression were increased, while the K+ transport through the inner membrane was decreased. These results indicate that there is a correlation between some mitochondrial activities and the development of somatic embryos. In particular, the K+ ATP channel was more active during the proliferation of ECMs, whereas the alternative pathways were activated during maturation of somatic embryos.