Fukaki H, Wysocka-Diller J, Kato T, Fujisawa H, Benfey P N, Tasaka M
Department of Botany, Graduate School of Science, Kyoto University, Japan.
Plant J. 1998 May;14(4):425-30. doi: 10.1046/j.1365-313x.1998.00137.x.
Shoots of higher plants exhibit negative gravitropism. However, little is known about the mechanism or site of gravity perception in shoots. We have identified two loci that are essential for normal shoot gravitropism in Arabidopsis thaliana. Genetic analysis demonstrated that the shoot gravitropism mutants sgr1 and sgr7 are allelic to the radial pattern mutants, scr and shr, respectively. Characterization of the aerial phenotype of these mutants revealed that the primary defect is the absence of a normal endodermis in hypocotyls and influorescence stems. This indicates that the endodermis is essential for shoot gravitropism and strongly suggests that this cell layer functions as the gravity-sensing cell layer in dicotyledonous plant shoots. These results also demonstrate that, in addition to their previously characterized role in root radial patterning, SCR and SHR regulate the radial organization of the shoot axial organs in Arabidopsis.
高等植物的茎表现出负向重力性。然而，关于茎中重力感知的机制或部位却知之甚少。我们已经鉴定出拟南芥中正常茎向重力性所必需的两个基因座。遗传分析表明，茎向重力性突变体sgr1和sgr7分别与径向模式突变体scr和shr等位。对这些突变体地上部分表型的特征分析表明，主要缺陷是下胚轴和花序茎中缺乏正常的内皮层。这表明内皮层对于茎的向重力性至关重要，并强烈暗示该细胞层在双子叶植物茎中作为重力感应细胞层发挥作用。这些结果还表明，除了它们先前在根径向模式形成中所具有的特征作用外，SCR和SHR还调节拟南芥茎轴向器官的径向组织。
