Two-Step Regulation of LAX PANICLE1 Protein Accumulation in Axillary Meristem Formation in Rice
Two-Step Regulation of LAX PANICLE1 Protein Accumulation in Axillary Meristem Formation in Rice
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DOI：
10.1105/tpc.108.065425
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发表时间：
2009-04-01
期刊：
影响因子：
11.6
通讯作者：
Kyozuka, Junko
中科院分区：
文献类型：
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作者：
Oikawa, Tetsuo;Kyozuka, Junko
腋生分生组织（AM）的形成是植物构型的重要决定因素。在水稻（Oryza sativa）中，LAX PANICLE 1（LAX1）功能是在整个植物寿命期间产生AM所必需的。在这里，我们显示AM启动和叶发育之间的密切关系，具体而言，叶发育的质体时4（P4）阶段是分生组织细胞增殖的关键。与此同时，LAX 1在P4期叶腋开始表达。LAX1 mRNA在起始AM和茎顶端分生组织之间的边界区域的两到三层细胞中积累。在lax1突变体中，分生组织细胞的增殖被启动，但未能进展为AM的形成。LAX1 mRNA表达及其作用位点的差异表明LAX1功能的非细胞自主特性。我们发现LAX1蛋白以阶段特异性和方向特异性的方式被运输到AM。此外，我们提出的证据表明，LAX1蛋白的运动是必需的LAX1的全部功能。因此，我们认为LAX1蛋白在P4阶段通过严格调节mRNA表达和随后控制蛋白运输在起始AM中瞬时积累。这两步调节对于新AM的建立至关重要。
Axillary meristem (AM) formation is an important determinant of plant architecture. In rice (Oryza sativa), LAX PANICLE1 (LAX1) function is required for the generation of AM throughout the plant's lifespan. Here, we show a close relationship between AM initiation and leaf development; specifically, the plastochron 4 (P4) stage of leaf development is crucial for the proliferation of meristematic cells. Coincident with this, LAX1 expression starts in the axils of leaves at P4 stage. LAX1 mRNA accumulates in two to three layers of cells in the boundary region between the initiating AM and the shoot apical meristem. In lax1 mutants, the proliferation of meristematic cells is initiated but fails to progress into the formation of AM. The difference in sites of LAX1 mRNA expression and its action suggests non-cell-autonomous characteristics of LAX1 function. We found that LAX1 protein is trafficked to AM in a stage- and direction-specific manner. Furthermore, we present evidence that LAX1 protein movement is required for the full function of LAX1. Thus, we propose that LAX1 protein accumulates transiently in the initiating AM at P4 stage by a strict regulation of mRNA expression and a subsequent control of protein trafficking. This two-step regulation is crucial to the establishment of the new AM.