Kawakatsu Taiji, Itoh Jun-Ichi, Miyoshi Kazumaru, Kurata Nori, Alvarez Nena, Veit Bruce, Nagato Yasuo
Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.
Plant Cell. 2006 Mar;18(3):612-25. doi: 10.1105/tpc.105.037622. Epub 2006 Feb 3.
In higher plants, leaves initiate in constant spatial and temporal patterns. Although the pattern of leaf initiation is a key element of plant shoot architecture, little is known about how the time interval between initiation events, termed plastochron, is regulated. Here, we present a detailed analysis of plastochron2 (pla2), a rice (Oryza sativa) mutant that exhibits shortened plastochron and precocious maturation of leaves during the vegetative phase and ectopic shoot formation during the reproductive phase. The corresponding PLA2 gene is revealed to be an orthologue of terminal ear1, a maize (Zea mays) gene that encodes a MEI2-like RNA binding protein. PLA2 is expressed predominantly in young leaf primordia. We show that PLA2 normally acts to retard the rate of leaf maturation but does so independently of PLA1, which encodes a member of the P450 family. Based on these analyses, we propose a model in which plastochron is determined by signals from immature leaves that act non-cell-autonomously in the shoot apical meristem to inhibit the initiation of new leaves.
在高等植物中，叶片以恒定的空间和时间模式起始。尽管叶片起始模式是植物茎结构的关键要素，但对于起始事件之间的时间间隔（即叶龄期）是如何调控的，人们知之甚少。在此，我们对叶龄期2（pla2）进行了详细分析，pla2是一种水稻（Oryza sativa）突变体，在营养生长阶段表现出缩短的叶龄期和叶片早熟，在生殖生长阶段表现出异位茎形成。相应的PLA2基因被揭示为终端穗1（terminal ear1）的直系同源基因，终端穗1是一个玉米（Zea mays）基因，编码一种MEI2样RNA结合蛋白。PLA2主要在幼叶原基中表达。我们表明，PLA2通常起到延缓叶片成熟速率的作用，但它的作用独立于PLA1，PLA1编码P450家族的一个成员。基于这些分析，我们提出了一个模型，其中叶龄期由来自未成熟叶片的信号决定，这些信号在茎尖分生组织中以非细胞自主的方式起作用，以抑制新叶的起始。
