FIGURE 4. Functional relationship between GN and GNL1.

a–d, PIN1 localization after BFA treatment. a, GN BFA-sensitive, GNL1 BFA-resistant (wild type): PIN1 is localized in BFA compartments and symmetrically at the plasma membrane. b, d, Polar localization of PIN1 at the plasma membrane and variable accumulation of PIN1 in BFA compartments when only GN (b) or both GN and GNL1 (d) are BFA-resistant. c, GN and GNL1 BFA-sensitive in gnl1 mutant background: PIN1 is localized in very small BFA compartments (arrowheads) and symmetrically at the plasma membrane (similar to wild type, Fig. 4a). Scale bars for a–d, 4 m. e, Promotor swaps between GN and GNL1 suggest asymmetric functional redundancy. f, g, Seedlings expressing different combinations of BFA-resistant (res.) versus BFA-sensitive (sens.) GNL1 and GNOM (GN) in gnl1 mutant background (except for wild-type) were treated with BFA. f, Left panel, additive effects of GNL1 and GN in primary root growth. Right panel, lateral root formation is mainly dependent on GN but not on GNL1. Error bars indicate standard deviation; n = 46 (GN BFA-res., GNL1 BFA-res.), 46 (GN BFA-res., GNL1 BFA-sens.), 22 (GN BFA-sens., GNL1 BFA-res., which corresponds to wild type), 25 (GN BFA-sens., GNL1 BFA-sens.). g, Root gravitropism is a GN-dependent process (upper panel, control; lower panel, BFA treatment).