The Calcineurin B-Like Ca2 Sensors CBL1 and CBL9 Function in Pollen Germination and Pollen Tube Growth in Arabidopsis
The Calcineurin B-Like Ca2 Sensors CBL1 and CBL9 Function in Pollen Germination and Pollen Tube Growth in Arabidopsis
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DOI：
10.1093/mp/sst095
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发表时间：
2013-07-01
期刊：
影响因子：
27.5
通讯作者：
Kudla, Joerg
中科院分区：
文献类型：
--
作者：
Maehs, Anette;Steinhorst, Leonie;Kudla, Joerg
本工作确定了拟南芥花粉萌发和花粉管生长的Ca-2传感器CBL 1和CBL 9的功能。正确调控CBL 1和CBL 9的表达并将这些蛋白质靶向质膜是正确的花粉萌发和管生长所必需的。这两种蛋白质的功能可能都与调节这些细胞中钾的稳态有关。Ca-2已被确定为调节花粉萌发和花粉管生长的重要第二信使。然而，到目前为止，只有少数信号转导元件已被确定为解码和中继Ca-2信号在不断增长的花粉管。在这里，我们报告的功能钙调磷酸酶B样（CBL）钙2传感器蛋白CBL 1和CBL 9从拟南芥花粉萌发和管生长。这两种蛋白质在成熟花粉和花粉管中表达，如果在烟草花粉中瞬时过表达，则会损害花粉管生长和形态。这些表型的诱导需要CBL 1的有效质膜靶向，并且不依赖于Ca-2与CBL 1的第四EF-手的结合。CBL 1或其最接近的同源物CBL 9在拟南芥中的过表达使花粉萌发和管生长对高外部K浓度高度敏感，而CBL 1和CBL 9的破坏降低了在低K条件下的花粉管生长。总之，我们的数据确定了CBL 1和CBL 9在花粉萌发和管生长中的关键功能，并提出了一个模型，其中这两种蛋白质通过调节K稳态作用于质膜。
This work identifies a function for the Ca-2 sensors CBL1 and CBL9 in pollen germination and tube growth in Arabidopsis. Faithfully regulated expression of CBL1 and CBL9 and targeting of these proteins to the plasma membrane are required for proper pollen germination and tube growth. The function of both proteins likely involves the regulation of K homeostasis in these cells.Ca-2 has been established as an important second messenger regulating pollen germination and tube growth. However, to date, only a few signaling components have been identified to decode and relay Ca-2 signals in growing pollen tubes. Here, we report a function for the calcineurin B-like (CBL) Ca-2 sensor proteins CBL1 and CBL9 from Arabidopsis in pollen germination and tube growth. Both proteins are expressed in mature pollen and pollen tubes and impair pollen tube growth and morphology if transiently overexpressed in tobacco pollen. The induction of these phenotypes requires efficient plasma membrane targeting of CBL1 and is independent of Ca-2 binding to the fourth EF-hand of CBL1. Overexpression of CBL1 or its closest homolog CBL9 in Arabidopsis renders pollen germination and tube growth hypersensitive towards high external K concentrations while disruption of CBL1 and CBL9 reduces pollen tube growth under low K conditions. Together, our data identify a crucial function for CBL1 and CBL9 in pollen germination and tube growth and suggest a model in which both proteins act at the plasma membrane through regulation of K homeostasis.