The shoot apical meristem restores its symplasmic organization during chilling-induced release from dormancy
The shoot apical meristem restores its symplasmic organization during chilling-induced release from dormancy
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DOI：
10.1046/j.1365-313x.2001.01022.x
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发表时间：
2001-05-01
期刊：
影响因子：
7.2
通讯作者：
van der Schoot, C
中科院分区：
文献类型：
--
作者：
Rinne, PLH;Kaikuranta, PM;van der Schoot, C
在白桦(Betula Pubescens)中，越冬多年生植物的顶端在生长季节结束时停止形态发生活动，并转变为休眠和耐寒的芽。这些事件由短光周期触发，涉及胞间连丝上含有1，3-β-D-葡聚糖的括约肌的产生。结果，所有的共质通路都关闭了。在这里，我们表明，通过低温打破芽的休眠包括恢复分生组织的共质组织。这种恢复可能是由1，3-β-D-葡聚糖酶介导的，该酶存在于休眠诱导过程中从头产生的小球体样空泡中。在冷藏过程中，这些液泡从块状细胞质移位到皮质细胞质，在那里它们与质膜排列在一起，通常与胞间连丝有关。在这一阶段，酶也出现在液泡外。在低温过程中，1，8-β-D-葡聚糖从胞间连丝通道和壁袖中消失，胞间连丝恢复了细胞间的运输能力，这一点可以通过显微注射荧光素黄CH和荧光素标记的赤霉酸来证明。综上所述，本实验表明，恢复分生组织的共质组织对于将芽从休眠状态中解脱出来和呈现增殖能力状态是必不可少的，并涉及到1，3-β-D-葡聚糖酶在胞间连丝中的作用。基于这些发现，我们提出了一个“休眠循环”模型，该模型描述了分生组织经历了三种连续的细胞通讯状态，对不同的环境线索具有特征的敏感性。
The shoot apex of overwintering perennials ceases its morphogenetic activity at the end of the growing season and transforms into a bud which is dormant and freezing-tolerant, In birch (Betula pubescens) these events are triggered by short photoperiod, and involve the production of 1,3-beta -D-glucan containing sphincters on the plasmodesmata. As a result, all symplasmic pathways shut down. Here we show that breakage of bud dormancy by chilling involves restoration of the symplasmic organization of the meristem. This restoration is likely to be mediated by 1,3-beta -D-glucanase, which was present in small spherosome-like vacuoles that arose de novo during dormancy induction. During chilling these vacuoles were displaced from the bulk cytoplasm to the cortical cytoplasm where they became aligned with the plasma membrane, often associated with plasmodesmata. At this stage the enzyme also appeared outside the vacuoles. During chilling, 1,8-beta -D-glucan disappeared from the plasmodesmal channels and wall sleeves, and the plasmodesmata regained the capacity for cell-cell transport, as demonstrated by microinjection of Lucifer Yellow CH and Fluorescein-tagged gibberellic acid. Collectively, the present experiments demonstrate that restoration of the symplasmic organization of the meristem is indispensable for the release of buds from dormancy and the assumption of a proliferation-competent state, and implicate 1,3-beta -D-glucanase action at the plasmodesmata. Based on these findings we propose a model for 'dormancy cycling' which depicts the meristem as passing through three sequential states of cellular communication with characteristic sensitivities to distinct environmental cues.