Figure 2.

Suc promotes rootward auxin transport. A, Suc increased primary root length. Higher endogenous auxin levels in the yucca-D mutants led to longer primary roots and a reduced response to Suc. Error bars represent se. B, Blocking auxin transport with 50 μm NPA eliminated Suc-induced hypocotyl elongation. Error bars represent se. C, Mutants with increased auxin transport (max2) were less sensitive to Suc. Ratios of hypocotyl length in Suc (S) versus non-Suc (N) conditions are indicated. Error bars represent se. D, Suc addition to wild-type (WT) seedlings (squares) increased sensitivity to the auxin transport inhibitor NPA, making them resemble max2 mutants (triangles) grown without Suc. Error bars represent se. Some error bars are within the boundaries of the markers. E, Suc induces expression of the gene encoding auxin efflux carrier PIN7 but has no measurable effects on genes encoding PIN1 or PIN3. Error bars represent se. F, Suc increases rootward auxin transport, as measured by the increased distance of auxin reporter staining from the site of local auxin application (depicted in the schematic at left). Exposing seedlings to increased light intensity (HL) was sufficient to increase staining distance. Bar = 1 mm for the no-Suc panel and 1.3 mm for all others. [See online article for color version of this figure.]