百脉根类LATERAL ORGAN BOUNDARIES基因的分离及表达方式

植物顶端分生组织可分为中央区，周缘区和肋区。在植物胚后发育中，侧生器官产生于顶端分生组织的周缘区。顶端分生组织和侧生器官之间的边界的建立和维持是一个非常重要的发育过程，许多调节子参与控制这个过程。拟南芥的LATERAL ORGAN BOUNDARIES（LOB）基因具有独特的表达模式，其表达的范围与上述的边界区域重合。LOB基因隶属于一个大的基因家族一，OB结构域基因家族。该家族编码的蛋白在N端具有一个保守的LOB结构域，该家族LOB基因以外的成员也参与拟南芥不同的发育过程。为了探讨在与拟南芥亲缘关系较远的豆科中LOB同源基因的功能，我们在豆科模式植物百脉根中分离了3个LOB同源基因，命名为LjLOB基因，并用RNA原位杂交方法研究了这3个基因的表达模式。研究结果显示，LjLOB1和LjLOB3都强烈地在小叶原基的基部表达，这种表达模式可能与小叶原基和复叶原基之间的边界相关。而LjLOB4则在发育中的花芽不同轮之间的边界上表达。百脉根中这3个基因具有不同的表达模式，强烈地提示它们的功能发生了分歧：LjLOB1和LjLDB3可能在复叶发育中具有重要功能；而LjLOB4则可能参与了花的发育。

Isolation and Expression Patterns of LATERAL ORGAN BOUNDARIES like Genes in Lotus japonicus

A shoot apical meristem (SAM) is composed of several distinct domains and lateral organs are initiated at the peripheral zone during plant development. Establishment and maintenance of boundary between SAM and lateral organs is an important developmental process, in which many regulators are involved. LATERAL ORGAN BOUNDARIES (LOB) in Arabidopsis, displaying a specific expression pattern corresponding to the boundary of developmental lateral organs, belongs to a large gene family--LOB domain gene family, which encode proteins with a conserved LOB domain at the N-terminus. Beside LOB, other members of this gene family are also involved in divergent developmental processes in Arabidopsis. To investigate the functions of LOB-like genes in the distantly related legumes, we isolated LjLOBs from a model legume plant Lotus japonicus, and conducted RNA in situ hybridization to investigate their expression patterns. It was found that LjLOB1 and LjLOB3 were strongly expressed at the bases of leaflet primordia, which coincided with the boundaries between leaflet primordia and compound leaf meristem, while LjLOB4 was expressed at the boundaries between whorls in the developing floral bud. The different special expression patterns of LjLOBs strongly suggest that their functions in L. japonicus may be divergent: LjLOB1 and LjLOB3 could play important roles in the control of compound leaf development, and LjLOB4 may be required during floral development.