Carbon metabolism in in vitro cultures of date palm: the role of carboxylases (PEPC and RubisCO)
While describing major trends of carbon metabolism during the initiation and expression of somatic embryogenesis in date palm (#Phoenix dactylifera# L., cv. Deglet Nour), we have investigated the role of two carboxylases, namely PEPC (Phosphoenolpyruvate carboxylase, EC 4.1.1.31) and RubisCO (Ribulose 1,5-bisphosphate carboxylase/oxygenase, EC 4.1.1.39), in embryogenic and non-embryogenic cultures. The detection of PEPC activity on polyacrylamide native gels after electrophoresis revealed the presence of 3 active isoforms in crude extracts from the embryogenic (E) callus strain, whereas only a single band was present in the nonembryogenic (NE) one. The level of PEPC specific capacity was of the same order (3.9 +- 1.2 micromol CO2/h/mg TSP) in both types of cultures. Further changes in carboxylase (PEPC and RubisCO) activities during the growth and development of somatic embryo-derived plantlets were also analysed. The PEPC/RubisCO ratio was found to progressively decrease (from 17.7 to 0.2) throughout the #in vitro# development of plantlets, due to a substantial depletion of PEPC activity, which decreased from 5.3 to 1.2 micromol CO2/h/mg TSP. Concomitantly, RubisCO assumed greater importance (from 0.3 to 5.3 micromol CO2/h/mg TSP) and became the main route for inorganic carbon fixation. Western blot analysis using polyclonal antibodies raised against PEPC and RubisCO purified from tobacco leaves confirmed this trend in terms of relative enzyme abundance.
| Main Authors: | , , , , , |
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| Format: | article biblioteca |
| Language: | eng |
| Subjects: | F02 - Multiplication végétative des plantes, F60 - Physiologie et biochimie végétale, Phoenix dactylifera, Embryogénèse somatique, cal, culture de tissu, phosphoenolpyruvate carboxylase, rubisco, activité enzymatique, teneur en protéines, nutrition des plantes, photosynthèse, développement biologique, http://aims.fao.org/aos/agrovoc/c_5791, http://aims.fao.org/aos/agrovoc/c_36911, http://aims.fao.org/aos/agrovoc/c_24576, http://aims.fao.org/aos/agrovoc/c_7789, http://aims.fao.org/aos/agrovoc/c_29524, http://aims.fao.org/aos/agrovoc/c_33542, http://aims.fao.org/aos/agrovoc/c_2604, http://aims.fao.org/aos/agrovoc/c_6251, http://aims.fao.org/aos/agrovoc/c_16379, http://aims.fao.org/aos/agrovoc/c_5812, http://aims.fao.org/aos/agrovoc/c_921, |
| Online Access: | http://agritrop.cirad.fr/392511/ http://agritrop.cirad.fr/392511/1/392511.pdf |
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