Actin dynamics in papilla cells of Brassica rapa during self- and cross-pollination
Actin dynamics in papilla cells of Brassica rapa during self- and cross-pollination
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DOI：
10.1104/pp.106.095273
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发表时间：
2007-05-01
期刊：
影响因子：
7.4
通讯作者：
Takayama, Seiji
中科院分区：
文献类型：
--
作者：
Iwano, Megumi;Shiba, Hiroshi;Takayama, Seiji
芸苔属植物的自交不亲和系统由S-位点控制，该位点含有S-受体激酶（SRK）和S-位点蛋白11（SP11）。SP11与SRK的结合诱导SRK自磷酸化，并启动导致自花花粉排斥的信号级联反应。然而，控制自花授粉过程中的水化和萌发停滞的机制尚不清楚。在这项研究中，我们研究了肌动蛋白的作用，一个关键的细胞骨架组成部分调节运输系统的水化和萌发的乳头细胞在授粉过程中。使用罗丹明鬼笔环肽染色，我们发现，异花授粉诱导肌动蛋白聚合，而自花授粉诱导肌动蛋白重组和可能解聚。通过监测瞬时表达的绿色荧光蛋白融合到肌动蛋白结合域的小鼠塔林，我们观察到的浓度肌动蛋白束在跨花粉附着位点和肌动蛋白重组和可能解聚在自花粉附着位点，结果对应于那些通过罗丹明鬼笔环肽染色。我们进一步表明，自花花粉的外壳足以介导这种反应。肌动蛋白解聚药物细胞松弛素D显着抑制花粉水合作用和萌发过程中异花授粉，进一步强调了肌动蛋白在这些过程中的作用。此外，三维电子显微镜断层扫描显示肌动蛋白细胞骨架与顶端空泡网络的密切联系。自花授粉破坏了液泡网络，而交叉授粉导致液泡重排的花粉附着的网站。两者合计，我们的数据表明，自花授粉和异花授粉差异影响肌动蛋白细胞骨架的动态，导致液泡结构的变化与水化和发芽。
The self-incompatibility system of the plant species Brassica is controlled by the S-locus, which contains S-RECEPTOR KINASE (SRK) and S-LOCUS PROTEIN11 (SP11). SP11 binding to SRK induces SRK autophosphorylation and initiates a signaling cascade leading to the rejection of self pollen. However, the mechanism controlling hydration and germination arrest during self-pollination is unclear. In this study, we examined the role of actin, a key cytoskeletal component regulating the transport system for hydration and germination in the papilla cell during pollination. Using rhodamine-phalloidin staining, we showed that cross-pollination induced actin polymerization, whereas self-pollination induced actin reorganization and likely depolymerization. By monitoring transiently expressed green fluorescent protein fused to the actin-binding domain of mouse talin, we observed the concentration of actin bundles at the cross-pollen attachment site and actin reorganization and likely depolymerization at the self-pollen attachment site; the results correspond to those obtained by rhodamine-phalloidin staining. We further showed that the coat of self pollen is sufficient to mediate this response. The actin-depolymerizing drug cytochalasin D significantly inhibited pollen hydration and germination during cross-pollination, further emphasizing a role for actin in these processes. Additionally, three-dimensional electron microscopic tomography revealed the close association of the actin cytoskeleton with an apical vacuole network. Self-pollination disrupted the vacuole network, whereas crosspollination led to vacuolar rearrangements toward the site of pollen attachment. Taken together, our data suggest that self- and cross-pollination differentially affect the dynamics of the actin cytoskeleton, leading to changes in vacuolar structure associated with hydration and germination.