ISHS Acta Horticulturae 520: XXV International Horticultural Congress, Part 10: Application of Biotechnology and Molecular Biology and Breeding - In Vitro Culture.
THE LONG-TERM EFFECTS OF SUCROSE ON ANAPLEROTIC CARBON FIXATION AND CARBON NITROGEN INTERACTION IN IN VITRO SOLANUM TUBEROSUM L. |
| Authors: | B.D. Sima, Y. Desjardins, V.Q. Le |
| Keywords: | Solanum tuberosum, in vitro, PEPCase |
| Abstract:
The effects of exogenous sucrose on in vitro potato (Solanum tuberosum, cv Kennebec) were evaluated. In the long-term experiments, plants were grown on in 3 different Murashige & Skoog media (MS): sucrose free MS; MS with 2% sucrose; N free MS with 2% sucrose. Plants fed with 2% sucrose exhibited higher PEPCase activity at 13, 26 and 39 days of culture. The highest accumulation of starch and sucrose was found in N depleted plants. This sugar accumulation indicates a competition between carbon skeleton utilisation and nitrogen metabolisms. Western blot comparisons of a 116 kDa PEPCase band found in all three treatments suggests regulation of the enzyme by sucrose. Short-term effects of sucrose on PEPCase activity by growing plants with 0% and 5% sucrose media. PEPCase activity measurements carried out at 4 hours intervals for 24 hours of culture in light and dark conditions, indicate higher PEPCase activity within the 5% sucrose treatment. However, light enhanced PEPCase activity, soluble sugar and nitrate contents. These results clearly show that exogenous sucrose participates in the long term to PEPCase regulation at the protein level. They also seem to indicate that sucrose metabolism is probalby involved in the replenishment of TCA cycle by providing carbon skeletons required to sustain PEP utilisation in times of high nitrate assimilation. | |
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