Effect of Mannose on Shoot Formation of Eplants

1363 WordsFeb 22, 20185 Pages
Results and Discussion Effect of mannose on shoot formation of explants As pBCAMBIA-PMI contains the pmi gene which confers mannose resistance, we used the mannose as a selection agent in our transformation experiments. Nine different concentrations and combinations of mannose and sucrose in shoot regeneration medium were used to evaluate the effect of mannose on the organogenesis of non-transformed tobacco leaf explants (Fig. 2). After 3 weeks cultivation, we found that no explants produced shoots on media without any tested carbon source (Fig. 2A). When cultivated on 30 gl-1 sucrose (0/30), 100% of the tobacco leaf explants regenerated. The organogenesis response decreased progressively when mannose concentration was increased in the shoot regeneration medium. A decreasing selectivity of mannose was also seen when 5 gl-1 sucrose was supplemented to the selection medium. Results show that the inhibitory effects of mannose increases with decreasing sucrose concentration in the medium, indicating an interaction between mannose and sucrose (Fig. 3). Similar results were described by Sigareva et al. (2004) in tomato as the addition of sucrose to the selection medium modulated the inhibitory effect of mannose on shoot formation. Earlier studies pointed that the indirect toxic effect of mannose caused by the conversion to mannose-6-phosphate by endogenous hexokinase increases with decreasing sucrose concentration in the medium, suggesting an interaction between mannose and

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