Periodic increases in elongation rate precede increases in cytosolic Ca2+ during pollen tube growth
Periodic increases in elongation rate precede increases in cytosolic Ca2+ during pollen tube growth
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DOI：
10.1006/dbio.2000.9709
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发表时间：
2000-06-01
影响因子：
2.7
通讯作者：
Robinson, KR
中科院分区：
文献类型：
--
作者：
Messerli, MA;Créton, R;Robinson, KR
在体外生长的花粉管需要细胞内高梯度的钙离子才能伸长。此外，在体外培养约2小时后，百合管顶端的钙离子和伸长率都开始有规律的、幅度较大的振荡，这就提出了这两种振荡之间的相位关系的问题。以前的研究缺乏时间分辨率来准确地建立这种关系。我们用一种新开发的高时间分辨率系统以及发光和荧光钙离子记录器的互补使用来研究这些振荡。结果表明，长花百合花粉管在振荡生长过程中伸长速率的周期性增长明显先于顶端钙离子的周期增长，平均周期为38.7+/-1.8M，比平均周期(38.7+/-1.8M)高出4.1U/-0.2M。此外，通过采集水杉碱光输出的图像，我们发现花粉管顶端的[Ca~(2+)]值在3~10mU/M之间振荡，远大于荧光指示剂所报道的幅度。我们提出了一个以周期生长和分泌为特征的解释模型，其中生长振荡产生了对随后的生长振荡至关重要的分泌。我们还关键地汇编了关于长花百合花柱生长速率的数据，这些数据与在最佳培养基中生长的花粉管的体外生长速率几乎没有变化。(C)2000年学术出版社。
Pollen tubes grown in vitro require an intracellular tip-high gradient of Ca2+ in order to elongate. Moreover, after about 2 h in vitro both the tip Ca2+ and the elongation rate of lily tubes begin to oscillate regularly with large amplitudes, This raises the question of the phase relation between these two oscillations. Previous studies lacked the temporal resolution to accurately establish this relationship. We have studied these oscillations with a newly developed, high temporal resolution system and the complementary use of both luminescent and fluorescent calcium reporters. We hereby show that the periodic increases in elongation rate during oscillatory growth of Lilium longiflorum pollen tubes clearly precede those in subtip calcium and do so by 4.1 +/- 0.2 s out of average periods of 38.7 +/- 1.8 s. Also, by collecting images of the light output of aequorin, we find that the magnitude of the [Ca2+] at the tip oscillates between 3 and 10 mu M, which is considerably greater than that reported by fluorescent indicators. We propose an explanatory model that features cyclic growth and secretion in which growth oscillations give rise to secretion that is essential for the subsequent growth oscillation, We also critically compile data on L. longiflorum stylar growth rates, which show little variation from in vitro rates of pollen tubes grown in optimal medium. (C) 2000 Academic Press.