In vitro Arabidopsis pollen germination and characterization of the inward potassium currents in Arabidopsis pollen grain protoplasts
In vitro Arabidopsis pollen germination and characterization of the inward potassium currents in Arabidopsis pollen grain protoplasts
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DOI：
10.1093/jexbot/52.361.1603
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发表时间：
2001-08-01
影响因子：
6.9
通讯作者：
Wu, WH
中科院分区：
文献类型：
--
作者：
Fan, LM;Wang, YF;Wu, WH
本研究的重点是研究K+内流对拟南芥花粉萌发和花粉管生长的调控作用。利用含琼脂培养基，首次成功建立了拟南芥花粉的体外萌发方法。培养6 h后，花粉萌发率接近75%，平均花粉管长度达到135 pm。外部K+浓度从1 mM降低到35 muM，花粉萌发抑制30%，花粉管生长抑制40%。外部K+浓度从1 mM增加到30 mM，刺激了花粉管生长，抑制了花粉萌发。为了研究钾离子内流与花粉萌发和花粉管生长的关系，我们利用花粉原生质体进行膜片钳全细胞记录，研究了花粉质膜内钾离子通道的调控。K+电流首次在拟南芥花粉原生质体中被发现。向内的K+电流对细胞质Ca2+的变化不敏感，但被高浓度的外部Ca2+抑制。外部Ca2+浓度从10 mM（对照）降低到1 mM对向内K+电流无显著影响，而外部Ca2+浓度从10 mM增加到50 mM对向内K+电流的抑制作用为46%。外部pH值的变化显著影响K+电流的大小、电导、电压无关的最大电导和激活动力学。本文讨论了钾离子通道介导的钾流入在拟南芥花粉萌发和管状生长过程中的生理重要性。
The focus of this study is to investigate the regulatory role of K+ influx in Arabidopsis pollen germination and pollen tube growth. Using agar-containing media, in vitro methods for Arabidopsis pollen germination have been successfully established for the first time. The pollen germination percentage was nearly 75% and the average pollen tube length reached 135 pm after a 6 h incubation. A decrease in external K+ concentration from 1 mM to 35 muM resulted in 30% inhibition of pollen germination and 40% inhibition of pollen tube growth. An increase in external K+ concentration from I mM to 30 mM stimulated pollen tube growth but inhibited pollen germination. To study how K+ influx is associated with pollen germination and tube growth, regulation of the inward K+ channels in the pollen plasma membrane was investigated by conducting patch-clamp whole-cell recording with pollen protoplasts. K+ currents were first identified in Arabidopsis pollen protoplasts. The inward K+ currents were insensitive to changes in cytoplasmic Ca2+ but were inhibited by a high concentration of external Ca2+. A decrease of external Ca2+ concentration from 10 mM (control) to 1 mM had no significant effect on the inward K+ currents, while an increase of external Ca2+ concentration from 10 mM to 50 mM inhibited the inward K+ currents by 46%. Changes in external pH significantly affected the magnitude, conductance, voltage-independent maximal conductance, and activation kinetics of the inward K+ currents. The physiological importance of potassium influx mediated by the inward K+-channels during Arabidopsis pollen germination and tube growth is discussed.