3.4 Decreased P causes reduction of P-containing glycolytic
intermediates under Al stress
Because P is an important substrate in glycolysis, we examined the
change of P and Pi in root tips in a time course of 2, 6, 24 and 72 h of
Al treatments. P concentration in the root tips of XZ29 remained
relatively constant over 72 h in Al treatment, whereas P levels in XZ9
decreased steadily throughout the treatment reaching 65% of control
levels by 72 h (Figure 5a). Compared to the Al-free controls, Pi
concentration in root tips of XZ29 increased significantly during the
first 6 h of Al treatment and then returned to control levels between 24
and 72 h (Figure 5b). By contrast, Pi concentrations in root tips of XZ9
showed no increase after 6 h, but these were decreased to 65% of
controls in 24 h and then remained stable at this lower level (Figure
5b).
The Al-induced changes of P and Pi concentrations showed similar pattern
as the changes of glycolytic intermediates, with greater decreases
occurring in XZ9 than XZ29 (Figures 4b, 5a, 5b). Also, there were
positive correlations between the P and Pi concentrations
and
P-containing
glycolytic
intermediates (Figure 5c). Thus, we investigated the response of
glycolytic intermediates levels to the addition of phosphate (150 μM
KH2PO4) after 72 h in Al treatment. We
found that the metabolites in Cluster 1 increased rapidly in both
accessions (Figures 5d, S9; Table S7).