Dinneny José R, Yadegari Ramin, Fischer Robert L, Yanofsky Martin F, Weigel Detlef
Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
Development. 2004 Mar;131(5):1101-10. doi: 10.1242/dev.00949.
Position-dependent regulation of growth is important for shaping organs in multicellular organisms. We have characterized the role of JAGGED, a gene that encodes a protein with a single C(2)H(2) zinc-finger domain, in controlling the morphogenesis of lateral organs in Arabidopsis thaliana. Loss of JAGGED function causes organs to have serrated margins. In leaves, the blade region is most severely affected. In sepals, petals and stamens, the strongest defects are seen in the distal regions. By monitoring cell-cycle activity in developing petals with the expression of HISTONE 4, we show that JAGGED suppresses the premature differentiation of tissues, which is necessary for the formation of the distal region. The localization of defects overlaps with the expression domain of JAGGED, which is restricted to the growing regions of lateral organs. JAGGED expression is notably absent from the cryptic bract, the remnant of a leaf-like organ that subtends the flower in many species but does not normally develop in wild-type Arabidopsis. If misexpressed, JAGGED can induce the formation of bracts, suggesting that the exclusion of JAGGED from the cryptic bract is a cause of bractless flowers in Arabidopsis.
生长的位置依赖性调控对于多细胞生物体中器官的形成至关重要。我们已经阐明了JAGGED（一个编码具有单个C(2)H(2)锌指结构域蛋白质的基因）在控制拟南芥侧生器官形态发生中的作用。JAGGED功能丧失会导致器官边缘呈锯齿状。在叶片中，叶片区域受影响最为严重。在萼片、花瓣和雄蕊中，最明显的缺陷出现在远端区域。通过用组蛋白4的表达监测发育中花瓣的细胞周期活性，我们发现JAGGED抑制组织的过早分化，这对于远端区域的形成是必要的。缺陷的定位与JAGGED的表达域重叠，JAGGED的表达域局限于侧生器官的生长区域。在许多物种中位于花下方的叶状器官残余——隐苞片中，明显没有JAGGED的表达，而在野生型拟南芥中隐苞片通常不发育。如果JAGGED错误表达，它可以诱导苞片的形成，这表明在拟南芥中隐苞片中排除JAGGED是无苞片花的一个原因。
