Figure 7.

The bacteria-plant combination produced a heat-labile compound in diluted root exudate that, when supplied to axenic plants, enhanced the Se concentration in roots 5-fold. The mean and sd values of three replicates are shown. Differences in root Se concentrations of axenic plants treated with growth medium (diluted root exudate) supplied with bacteria and axenic plants treated with root exudate or boiled exudate were significant (P < 0.05). The root exudate from axenic plants or plants grown with strain BJ2 was filtered through a 0.22-μm filter to remove bacteria, and then added to a fresh batch of axenic plants with 20 μm selenate.