植物生命周期中最脆弱的阶段之一是有性生殖,这取决于有效的花粉转移,而且对花粉粒的耐热性也有影响。花粉的耐热性与温度有关,并且可能因与全球变暖相关的温度升高而降低。越来越多的研究集中在温度升高对作物花粉耐热性的影响上,以了解极端温度对产量的可能影响。然而,温度对野生植物花粉耐热性的影响鲜为人知。为了填补这个空白,我们选择了莲花s.l.(豆科),许多欧洲栖息地常见的物种,并进行了实验室实验以测试其花粉耐热性,以响应人工温度升高。为了测试花粉耐热性可能的局部适应性,我们比较了六个低地(389-451ma.s.l.)和六个高地(841-1,030ma.s.l.)人口的数据。我们在15°C下观察了花粉的体外萌发,25°C,30°C,和40°C。虽然低地植物在较宽的温度范围内(15-30°C)保持稳定的发芽率,并且仅在极高的温度(40°C)下表现出降低的发芽率,即使在30°C的温度下,高地植物的发芽也减少了,在温暖的夏天,低地通常会超过温度。这表明落叶松的低地种群可能在当地适应较高的温度以进行花粉萌发。另一方面,在低地和高原植物中,花粉管长度随温度升高而降低。低地和高地种群的总体平均花粉发芽率显着不同,高地种群显示出较高的发芽率。另一方面,高原种群的平均花粉管长度略小。总之,我们发现,在高温下,落叶松的花粉耐热性降低,而生长在较高海拔的植物种群的花粉萌发对温度升高更敏感,这表明花粉耐热性的可能的局部适应。
One of the most vulnerable phases in the plant life cycle is sexual reproduction, which depends on effective pollen transfer, but also on the thermotolerance of pollen grains. Pollen thermotolerance is temperature-dependent and may be reduced by increasing temperature associated with global warming. A growing body of research has focused on the effect of increased temperature on pollen thermotolerance in crops to understand the possible impact of temperature extremes on yield. Yet, little is known about the effects of temperature on pollen thermotolerance of wild plant species. To fill this gap, we selected Lotus corniculatus s.l. (Fabaceae), a species common to many European habitats and conducted laboratory experiments to test its pollen thermotolerance in response to artificial increase in temperature. To test for possible local adaptation of pollen thermal tolerance, we compared data from six lowland (389-451 m a.s.l.) and six highland (841-1,030 m a.s.l.) populations. We observed pollen germination in vitro at 15 °C, 25 °C, 30 °C, and 40 °C. While lowland plants maintained a stable germination percentage across a broad temperature range (15-30 °C) and exhibited reduced germination only at extremely high temperatures (40 °C), highland plants experienced reduced germination even at 30 °C-temperatures commonly exceeded in lowlands during warm summers. This suggests that lowland populations of L. corniculatus may be locally adapted to higher temperature for pollen germination. On the other hand, pollen tube length decreased with increasing temperature in a similar way in lowland and highland plants. The overall average pollen germination percentage significantly differed between lowland and highland populations, with highland populations displaying higher germination percentage. On the other hand, the average pollen tube length was slightly smaller in highland populations. In conclusion, we found that pollen thermotolerance of L. corniculatus is reduced at high temperature and that the germination of pollen from plant populations growing at higher elevations is more sensitive to increased temperature, which suggests possible local adaptation of pollen thermotolerance.