Gabaculine as a tool to investigate the polyamine biosynthesis pathway in habituated callus of Beta vulgaris (L.)

Abstract

The polyamine content of a habituated callus of Beta vulgaris (L.) is strongly diminished after treatment with gabaculine, a potent inhibitor of ornithine aminotransferase. The inhibitory effect of gabaculine is reversed if ornithine is supplied. This result may indicate that proline catabolism provides ornithine for polyamine synthesis.

Disturbed sugar metabolism in a fully habituated nonorganogenic callus of Beta vulgaris (L.)

“…The ratio was always higher than 1 over the culture duration . This callus which has been characterized previously in terms of nitrogen metabolism perturbation [16] also appears to diverge in terms of its sugar metabolism, favouring the HMP pathway at the expense of glycolysis . The high fructose/glucose ratio in the H callus is probably due to a change in the metabolism of hexoses .…”

“…The high fructose/glucose ratio in the H callus is probably due to a change in the metabolism of hexoses . The redirection of nitrogen metabolism towards polyamine synthesis observed in the H callus over 14 days of culture [16] might also be an important source of H 2 0 2 , as far as polyamines catabolism is concerned [1] . N) .…”

“…This fact and the higher levels of superoxide dismutase and glutathione reductase [10] in the H callus than in N cells suggest that the H callus undergoes oxidative stress . The H cells have also been characterized by an important deviation in nitrogen metabolism which leads to the accumulation of proline and polyamines [16] . The H cells have also been characterized by an important deviation in nitrogen metabolism which leads to the accumulation of proline and polyamines [16] .…”