UFO in the Arabidopsis inflorescence apex is required for floral-meristem identity and bract suppression
UFO in the Arabidopsis inflorescence apex is required for floral-meristem identity and bract suppression
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DOI：
10.1007/s00425-005-0138-3
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发表时间：
2006-03-01
期刊：
影响因子：
4.3
通讯作者：
Haughn, GW
中科院分区：
文献类型：
--
作者：
Hepworth, SR;Klenz, JE;Haughn, GW
拟南芥的不寻常的花器官（UFO）基因编码的F盒蛋白所需的确定花器官和花分生组织的身份。UFO的突变导致花器官类型的巨大变化，这是很好的特点，而花序缺陷更微妙，更少了解。这些缺陷包括次生花序数量的增加，在形成花和次生花序之间交替的节，以及其中一朵花被苞片包着的节。在这里，我们展示了花序缺陷如何与花原基的异常发育相关，并在此过程中建立了对UFO的时间要求。在不明飞行物突变体的花序顶端，新形成的原基最初是苞片状的。花分生组织身份基因LFY和AP 1的表达局限于这些原基的相对较小的近轴区域，在包含原基的平衡的细胞中观察到苞片身份标记FIL的表达。在这些早期原基的近轴区域中的细胞增殖被几个节延迟，使得原基在几个节处出现“嵌合”，具有可见的花和苞片组分。然而，到花发育的第二阶段，苞片的生长一般停止，并被花原基的发育所取代。这种花分生组织发育的异常模式不能通过来自API启动子的UFO表达来拯救，表明在API激活之前，花原基的正常发育需要UFO。我们建议，UFO和LFY共同需要在花序分生组织，以促进花分生组织的发展和抑制，在一个非细胞自主的方式，生长的苞片。
The UNUSUAL FLORAL ORGANS (UFO) gene of Arabidopsis encodes an F-box protein required for the determination of floral-organ and floral-meristem identity. Mutation of UFO leads to dramatic changes in floral-organ type which are well-characterized whereas inflorescence defects are more subtle and less understood. These defects include an increase in the number of secondary inflorescences, nodes that alternate between forming flowers and secondary inflorescences, and nodes in which a single flower is subtended by a bract. Here, we show how inflorescence defects correlate with the abnormal development of floral primordia and establish a temporal requirement for UFO in this process. At the inflorescence apex of ufo Mutants, newly formed primordia are initially bract-like. Expression of the floral-meristem identity genes LFY and AP1 are confined to a relatively small adaxial region of these primordia with expression of the bract-identity marker FIL observed in cells that comprise the balance of the primordia. Proliferation of cells in the adaxial region of these early primordia is delayed by several nodes such that primordia appear "chimeric" at several nodes, having visible floral and bract components. However, by late stage 2 of floral development, growth of the bract generally ceases and is overtaken by development of the floral primordium. This abnormal pattern of floral meristem development is not rescued by expression of UFO from the API promoter, indicating that UFO is required prior to API activation for normal development of floral primordia. We propose that UFO and LFY are jointly required in the inflorescence meristem to both promote floral meristem development and inhibit, in a non-cell autonomous manner, growth of the bract.