Role of the Too Many Mouths Gene in the Regulation of Asymmetric Divisions and Stomatal Patterning

气孔由特殊的表皮细胞组成，调节光合作用的气体交换，对植物生产力至关重要。 它们也是研究不对称分裂在植物细胞命运特化和细胞图案形成中的作用的一个有价值的发育系统。 在野生型植物中，气孔间隔至少一个细胞。 在拟南芥中，这种间隔模式是通过不对称分裂产生的，这种不对称分裂是通过明显的细胞间通讯来确定这些分裂相对于预先存在的气孔或前体的方向。 toomanymouths（TMM）突变诱导气孔簇的叶片，导致过度的不对称分裂，往往是错误的方向。 这种表型表明TMM的功能是参考或解释空间信息，以正确定位和分配细胞命运决定因素。 与叶中的气孔群聚相反，tmm消除了茎等其他器官中气孔的形成。 这些相反的表型表明TMM在几个不同的水平上对气孔的产生和形成起着关键作用。 这项工作的重点是完成TMM基因的测序;确定其在野生型植物和气孔模式突变体中的表达模式;分析其在转基因植物中的错误表达的影响;模式和错误模式的细胞学特征;以及茎中气孔形成是如何被抑制的发育分析。 长期的目标是确定关键的命运决定因素和基因和事件参与细胞信号在气孔图案。

Stomata consist of specialized epidermal cells that regulate gas exchangefor photosynthesis and are essential for plant productivity. They are alsoa valuable developmental system for studying the role of asymmetricdivisions in cell fate specification and in cell patterning in plants. Inwild-type plants, stomata are spaced at least one cell apart. This spacingpattern is generated in Arabidopsis through asymmetric divisions that areextrinsically referenced through apparent cell-cell communication to orientthose divisions with respect to a pre-existing stoma or precursor. The toomany mouths (TMM) mutation induces stomatal clusters in leaves that resultfrom excess asymmetric divisions that are often misoriented. Thisphenotype suggests that TMM functions in referencing or interpretingspatial information to correctly position and allocate cell fatedeterminants. In contrast to the stomatal clustering found in leaves, tmmeliminates the formation of stomata in other organs such as stems. Theseopposite phenotypes indicate that TMM plays a key role in stomatalproduction and patterning at several different levels. The work proposedfocuses on the completion of the sequencing of the TMM gene; thedetermination of its expression pattern in wild-type plants and in stomatalpatterning mutants; the analysis of the effects of its misexpression intransgenic plants; the characterization of the cytology of patterning andmispatterning; and a developmental analysis of how stomatal formation issuppressed in stems. Long term goals are to identify key fate determinantsand the genes and events involved in cell signaling in stomatal patterning.