Long-chain base phosphates modulate pollen tube growth via channel-mediated influx of calcium.
Long-chain base phosphates modulate pollen tube growth via channel-mediated influx of calcium.
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DOI：
10.1111/tpj.12576
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发表时间：
2014-08
期刊：
影响因子：
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通讯作者：
Juyou Wu;Xiaoya Qin;S. Tao;Xueting Jiang;Yun-Kuan Liang;Shaoling Zhang
中科院分区：
文献类型：
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作者：
Juyou Wu;Xiaoya Qin;S. Tao;Xueting Jiang;Yun-Kuan Liang;Shaoling Zhang
长链碱基磷酸盐(LCBPs)与动物体内从细胞增殖到细胞凋亡等一系列重要的生物学过程有关。然而，它们在植物中的功能在很大程度上仍不清楚。在这里，我们报道了LCBPs，鞘氨醇-1-磷酸(S1P)和植酸鞘氨醇-1-磷酸(Phyto-S1P)，以浓度依赖的双相方式调节花粉管的生长。与野生型拟南芥相比，SPHK1过表达(SPHK1-OE)促进了花柱传递组织中花粉管的生长，但SPHK1基因敲除(SPHK1-KD)抑制了花粉管的生长；然而，SPHK1的错误表达对花粉管的体外生长没有明显的影响。有趣的是，外源S1P或Phyto-S1P处理可以提高SPHK1-OE、SPHK1-KD和野生型拟南芥的花粉管生长速率。钙离子(Ca(2+))-图像分析表明，S1P能显著提高花粉细胞内钙离子浓度。胞外S1P可诱导花粉质膜上超极化激活的Ca(2+)电流，该电流的激活由异源三聚体G蛋白介导。此外，S1P诱导的胞内游离Ca(2+)的增加抑制了钾离子进入花粉管的过程。我们的发现表明，LCBPs在促进Ca(2+)内流和调节花粉管生长的信号级联中发挥作用。
Long-chain base phosphates (LCBPs) have been correlated with amounts of crucial biological processes ranging from cell proliferation to apoptosis in animals. However, their functions in plants remain largely unknown. Here, we report that LCBPs, sphingosine-1-phosphate (S1P) and phytosphingosine-1-phosphate (Phyto-S1P), modulate pollen tube growth in a concentration-dependent bi-phasic manner. The pollen tube growth in the stylar transmitting tissue was promoted by SPHK1 overexpression (SPHK1-OE) but dampened by SPHK1 knockdown (SPHK1-KD) compared with wild-type of Arabidopsis; however, there was no detectable effect on in vitro pollen tube growth caused by misexpression of SPHK1. Interestingly, exogenous S1P or Phyto-S1P applications could increase the pollen tube growth rate in SPHK1-OE, SPHK1-KD and wild-type of Arabidopsis. Calcium ion (Ca(2+) )-imaging analysis showed that S1P triggered a remarkable increase in cytosolic Ca(2+) concentration in pollen. Extracellular S1P induced hyperpolarization-activated Ca(2+) currents in the pollen plasma membrane, and the Ca(2+) current activation was mediated by heterotrimeric G proteins. Moreover, the S1P-induced increase of cytosolic free Ca(2+) inhibited the influx of potassium ions in pollen tubes. Our findings suggest that LCBPs functions in a signaling cascade that facilitates Ca(2+) influx and modulates pollen tube growth.