Brassinosteroids promote Arabidopsis pollen germination and growth
Brassinosteroids promote Arabidopsis pollen germination and growth
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DOI：
10.1007/s00497-014-0247-x
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发表时间：
2014-07
影响因子：
3.4
通讯作者：
F. Vogler;Christina Schmalzl;Maria Englhart;Martin Bircheneder;S. Sprunck
中科院分区：
文献类型：
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作者：
F. Vogler;Christina Schmalzl;Maria Englhart;Martin Bircheneder;S. Sprunck
花粉管是植物顶端生长最快的细胞之一，是研究细胞极化生长的动力学和时空调控的理想实验系统。然而，研究模式植物拟南芥中的花粉管尖端生长仍然很困难，因为体外花粉萌发和花粉管生长速率变化很大，与雌蕊中观察到的差异很大，很可能是由于雌性生殖道的生长促进特性。我们发现，在体外培养的拟南芥花粉响应油菜素类固醇（BR）的剂量依赖性的方式。当培养基中添加10 µM表油菜素（epiBL）时，花粉萌发和花粉管生长分别增加了9倍和5倍，导致生长动力学更类似于体内生长。表达分析表明，BR生物合成的关键酶之一，CYP 90 A1/CPD的启动子，是高度活跃的生殖道细胞，形成从柱头到胚珠的花粉管通道。与野生型或BR感知突变体相比，acyp 90 a1突变体的花粉管通过生殖道生长显著缩短。我们的研究结果表明，epiBL促进花粉萌发和试管生长在体外，并建议生殖道的细胞提供BR化合物刺激花粉管生长。
Pollen tubes are among the fastest tip-growing plant cells and represent an excellent experimental system for studying the dynamics and spatiotemporal control of polarized cell growth. However, investigating pollen tube tip growth in the model plant Arabidopsis remains difficult because in vitro pollen germination and pollen tube growth rates are highly variable and largely different from those observed in pistils, most likely due to growth-promoting properties of the female reproductive tract. We found that in vitro grown Arabidopsis pollen respond to brassinosteroid (BR) in a dose-dependent manner. Pollen germination and pollen tube growth increased nine- and fivefold, respectively, when media were supplemented with 10 µM epibrassinolide (epiBL), resulting in growth kinetics more similar to growth in vivo. Expression analyses show that the promoter of one of the key enzymes in BR biosynthesis,CYP90A1/CPD,is highly active in the cells of the reproductive tract that form the pathway for pollen tubes from the stigma to the ovules. Pollen tubes grew significantly shorter through the reproductive tract of acyp90a1mutant compared to the wild type, or to a BR perception mutant. Our results show that epiBL promotes pollen germination and tube growth in vitro and suggest that the cells of the reproductive tract provide BR compounds to stimulate pollen tube growth.