Involvement of SLs in shoot gravitropism is conserved in Arabidopsis. (A) Photographs of wild-type (Col-0), max2, and max4 hypocotyls with or without GR24 treatment upon gravistimulation. (Scale bar: 0.5 cm.) (B) Statistic analysis of hypocotyl curvature in 4-d-old dark-grown wild-type, max2, and max4 seedlings with or without GR24 treatment upon 6 h of gravistimulation. Error bars represent SEM; n = 50. Means with different letters indicate a significant difference (P < 0.01; ANOVA). (C) Photographs of inflorescence stems of wild-type, max2, max4, Atla1, Atla1 max2, and Atla1 max4 seedlings upon 12 h of gravistimulation. (Scale bar: 2 cm.) (D) Kinetic analysis of inflorescence stem curvature in wild-type, max2, max4, Atla1, Atla1 max2, and Atla1 max4 seedlings upon gravistimulation. Values represent the mean ± SEM; n = 10. (E) Quantification of IAA levels in 7-d-old light-grown wild-type, max2, max4, and Atla1 seedlings. Error bars indicate SEM; n = 3. *P < 0.05; Student t test.