ISHS Acta Horticulturae 748: II International Symposium on Acclimatization and Establishment of Micropropagated Plants
EFFECTS OF AUTOTROPHIC AND MIXOTROPHIC TISSUE CULTURE CONDITIONS ON THE EXPRESSION OF PRIMARY METABOLISM GENES OF TOMATO PLANTLETS |
| Authors: | J.-F. Dubuc, Y. Desjardins |
| Keywords: | in vitro, ex vitro, photosynthesis, real-time PCR, acclimatization, gene expression, Lycopersicon esculentum |
| Abstract:
The impact of in vitro culture conditions on photosynthesis and expression of genes of the primary metabolism where studied under autotrophic (180 μmol m-2 • s-1, 0% sucrose) and mixotrophic (60 μmol m-2 • s-1, 3% sucrose) in vitro conditions and after ex vitro acclimatization. Tomato plantlets (Lycopersicon esculentum Mill.) were used to study the stimulation or inhibition of the expression of acid invertase (INV), sucrose-phosphate synthase (SPS), ribulose-1,5-biphosphate carboxylase/oxygenase (RbcL), phosphoenolpyruvate carboxylase (ppc1), glutamine synthetase (GS), nitrate reductase (NR) and ubiquitin (ubi3) gene. Real-time quantitative PCR showed that exogenous sugar caused a marked increase of INV expression in vitro. Results obtained for in vitro plantlets show that gene expression dor RbcL, NR, GS and Ubi are much larger than those of ex vitro plantlets. The high level of nitrogen in vitro upregulates amino acid biosynthesis. RbcL could have a role of nitrogen storage and also of detoxification of the high level of nitrogen in the growth media. When transferred ex vitro, plantlets cultured under mixotrophic conditions show a lower level of transcripts than plantlets grown in absence of sugar in the medium. This demonstrates that plantlets grown in presence of exogenous sucrose are submitted to a major change in metabolism upon transferred to ex vitro autotrophic growth. | |
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