Woll Katrin, Borsuk Lisa A, Stransky Harald, Nettleton Dan, Schnable Patrick S, Hochholdinger Frank
Center for Plant Molecular Biology, Department of General Genetics , Eberhard Karls University, 72076 Tuebingen, Germany.
Plant Physiol. 2005 Nov;139(3):1255-67. doi: 10.1104/pp.105.067330. Epub 2005 Oct 7.
The monogenic recessive maize (Zea mays) mutant rootless with undetectable meristems 1 (rum1) is deficient in the initiation of the embryonic seminal roots and the postembryonic lateral roots at the primary root. Lateral root initiation at the shoot-borne roots and development of the aerial parts of the mutant rum1 are not affected. The mutant rum1 displays severely reduced auxin transport in the primary root and a delayed gravitropic response. Exogenously applied auxin does not induce lateral roots in the primary root of rum1. Lateral roots are initiated in a specific cell type, the pericycle. Cell-type-specific transcriptome profiling of the primary root pericycle 64 h after germination, thus before lateral root initiation, via a combination of laser capture microdissection and subsequent microarray analyses of 12k maize microarray chips revealed 90 genes preferentially expressed in the wild-type pericycle and 73 genes preferentially expressed in the rum1 pericycle (fold change >2; P-value <0.01; estimated false discovery rate of 13.8%). Among the 51 annotated genes predominately expressed in the wild-type pericycle, 19 genes are involved in signal transduction, transcription, and the cell cycle. This analysis defines an array of genes that is active before lateral root initiation and will contribute to the identification of checkpoints involved in lateral root formation downstream of rum1.
单基因隐性玉米（Zea mays）突变体无根且分生组织不可检测1（rum1）在胚胎胚根起始以及初生根上的胚后侧根起始方面存在缺陷。突变体rum1在茎生根上的侧根起始以及地上部分的发育不受影响。突变体rum1在初生根中生长素运输严重减少，重力反应延迟。外源施加生长素不会在rum1的初生根中诱导侧根形成。侧根在特定细胞类型即中柱鞘中起始。通过激光捕获显微切割以及随后对12k玉米微阵列芯片进行微阵列分析，对萌发64小时后（即侧根起始之前）的初生根中柱鞘进行细胞类型特异性转录组分析，结果显示90个基因在野生型中柱鞘中优先表达，73个基因在rum1中柱鞘中优先表达（倍数变化>2；P值<0.01；估计错误发现率为13.8%）。在主要在野生型中柱鞘中表达的51个注释基因中，19个基因参与信号转导、转录和细胞周期。该分析确定了一系列在侧根起始之前活跃的基因，将有助于鉴定rum1下游参与侧根形成的检查点。
