Figure 4.

Downstream catabolites are unable to reverse the growth inhibition of Arabidopsis seedlings by DF. Protocol as described in the legend to Figure 2, except that the agar medium was supplemented with 250 μm hypoxanthine alone (top), hypoxanthine and 300 nm DF (upper middle), 250 μm xanthine alone (lower middle), or xanthine and 300 nm DF (bottom). Seedling wet weights following root excision (mean ± sd, n = 4, except hypoxanthine alone [n = 3]) are listed at the right. *, P < 0.05 when compared to the corresponding purine base alone condition in an unpaired two-tailed t test. Seedlings shown represent those closest to the average for the group.