Department of Biology, Portland State University, PO Box 751, Portland, OR 97207-0751, USA.
Biol Lett. 2009 Dec 23;5(6):857-60. doi: 10.1098/rsbl.2009.0380. Epub 2009 Jul 29.
Non-vascular plants rely on sperm to cross the distance between male and female reproductive organs for fertilization and sexual reproduction to occur. The majority of non-vascular plants have separate sexes, and thus, this distance may be a few millimetres to many metres. Because sperm need water for transport, it has been assumed that sperm lifespans are short and that this type of sexual reproduction limits the expansion of non-vascular plants in terrestrial environments. However, little data is available on the lifespan of sperm in non-vascular plants, and none is available for bryophytes, the group thought to have first colonized terrestrial habitats. Here, we documented the lifespan of sperm of Pohlia nutans, collected from a geothermal spring's area, and tested the effects of variation under environmental conditions on this lifespan. Surprisingly, 20 per cent of the sperm were still motile after 100 h, and sperm lifespan was not significantly affected by temperature variation between 22 and 60 degrees C. Lifespan was significantly affected by sperm dilution and temperatures above 75 degrees C. These results suggest the need to reconsider the importance of sperm motility in bryophyte fertilization.
非维管束植物依靠精子在雄性和雌性生殖器官之间移动来进行受精和有性繁殖。大多数非维管束植物具有不同的性别，因此，这个距离可能只有几毫米到几米。由于精子在运输过程中需要水，因此人们一直认为精子的寿命很短，这种有性繁殖限制了非维管束植物在陆地环境中的扩张。然而，关于非维管束植物精子寿命的数据很少，而对于被认为首先在陆地栖息地定居的苔藓植物来说，则没有这方面的数据。在这里，我们记录了从温泉地区采集的 Pohlia nutans 精子的寿命，并测试了环境条件下变化对这种寿命的影响。令人惊讶的是，在 100 小时后，仍有 20%的精子具有运动能力，而精子寿命不受 22 至 60 摄氏度之间温度变化的显著影响。精子稀释和温度高于 75 摄氏度对寿命有显著影响。这些结果表明，有必要重新考虑精子活力在苔藓植物受精中的重要性。
