A calcium-dependent protein kinase interacts with and activates a calcium channel to regulate pollen tube growth.
A calcium-dependent protein kinase interacts with and activates a calcium channel to regulate pollen tube growth.
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DOI：
10.1093/mp/sst125
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发表时间：
2014-02
期刊：
影响因子：
27.5
通讯作者：
Liming Zhou;Wenzhi Lan;Yuan-Qing Jiang;Wei-Ling Fang;S. Luan
中科院分区：
文献类型：
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作者：
Liming Zhou;Wenzhi Lan;Yuan-Qing Jiang;Wei-Ling Fang;S. Luan
钙作为一种普遍存在的第二信使，在动物神经元、植物花粉管和根毛等尖端生长细胞中起着重要作用。然而，关于植物中编码和解码Ca（2+）信号的调节机制却知之甚少。这里提出的证据表明，钙依赖性蛋白激酶，CPK32，控制极性生长的花粉管。CPK 32的过表达破坏了极性生长沿着的生长，并导致顶端Ca（2+）的过度积累。对CPK32的下游效应分子的搜索导致鉴定了环核苷酸门控通道CNGC 18作为CPK32的相互作用伴侣。CPK32和CNGC 18的共表达导致爪蟾卵母细胞中CNGC 18的活化，其中单独表达CNGC 18没有表现出显著的钙通道活性。CNGC 18的过表达产生了一种生长停滞表型，并伴随着尖端钙的积累，类似于CPK 32过表达所诱导的。CPK32和CNGC 18的共表达具有协同效应，导致更严重的花粉管生长的去极化。这些结果提供了一种潜在的前馈机制，其中钙激活的CPK 32激活CNGC 18，进一步促进在花粉管极性生长中Ca（2+）振荡的升高阶段的钙进入。
Calcium, as a ubiquitous second messenger, plays essential roles in tip-growing cells, such as animal neurons, plant pollen tubes, and root hairs. However, little is known concerning the regulatory mechanisms that code and decode Ca(2+) signals in plants. The evidence presented here indicates that a calcium-dependent protein kinase, CPK32, controls polar growth of pollen tubes. Overexpression of CPK32 disrupted the polar growth along with excessive Ca(2+) accumulation in the tip. A search of downstream effector molecules for CPK32 led to identification of a cyclic nucleotide-gated channel, CNGC18, as an interacting partner for CPK32. Co-expression of CPK32 and CNGC18 resulted in activation of CNGC18 in Xenopus oocytes where expression of CNGC18 alone did not exhibit significant calcium channel activity. Overexpression of CNGC18 produced a growth arrest phenotype coupled with accumulation of calcium in the tip, similar to that induced by CPK32 overexpression. Co-expression of CPK32 and CNGC18 had a synergistic effect leading to more severe depolarization of pollen tube growth. These results provide a potential feed-forward mechanism in which calcium-activated CPK32 activates CNGC18, further promoting calcium entry during the elevation phase of Ca(2+) oscillations in the polar growth of pollen tubes.