目的:开花时间通常与纬度相关,指示气候梯度。温带物种的开花通常需要暴露在寒冷的温度下,被称为春化。因此,开花开始随纬度的种群分化可能反映了对种群经历的当地气候条件的适应。
方法:在其西部范围内,来自Linumbienne种群的种子(栽培Linumusitatissimum的野生亲戚)用于描述开花开始的纬度分化,以确定其与种群当地气候的关联。使用包括不同作物品种的春化实验来确定春化如何加速开花开始,除了种群和品种之间的春化敏感性反应。此外,使用微卫星标记对沿纬度范围的比安乳杆菌种群的遗传分化进行了审查。
结果:开花开始随起源纬度而变化,南方人口开花比北方人口早。春化减少了开花开始的天数,但是与南部人群相比,北部人群的春化敏感性更高。相反,春化延迟了作物的开花开始,灵敏度变化较小。在L.Bienne,人口的当地气候比纬度本身更好地预测了开花的开始和春化敏感性。微卫星数据揭示了种群的遗传分化,形成沿纬度地理划分的两组。
结论:在实验中对纬度变化的一致发现表明,比安乳杆菌种群的开花开始和春化敏感性均处于遗传调控之下,可能取决于产地的气候线索。与纬度气候梯度的关联表明,局部经历的气候驱动了开花开始和春化敏感性模式的种群分化。遗传种群结构表明,过去的种群历史可能影响了检测到的开花起始模式,这值得进一步的工作。
OBJECTIVE: The timing of flowering onset is often correlated with latitude, indicative of climatic gradients. Flowering onset in temperate species commonly requires exposure to cold temperatures, known as vernalization. Hence, population differentiation of flowering onset with latitude might reflect adaptation to the local climatic conditions experienced by populations.
METHODS: Within its western range, seeds from Linum bienne populations (the wild relative of cultivated Linum usitatissimum) were used to describe the latitudinal differentiation of flowering onset to determine its association with the local climate of the population. A vernalization experiment including different crop cultivars was used to determine how vernalization accelerates flowering onset, in addition to the vernalization sensitivity response among populations and cultivars. Additionally, genetic differentiation of L. bienne populations along the latitudinal range was scrutinized using microsatellite markers.
RESULTS: Flowering onset varied with latitude of origin, with southern populations flowering earlier than their northern counterparts. Vernalization reduced the number of days to flowering onset, but vernalization sensitivity was greater in northern populations compared with southern ones. Conversely, vernalization delayed flowering onset in the crop, exhibiting less variation in sensitivity. In L. bienne, both flowering onset and vernalization sensitivity were better predicted by the local climate of the population than by latitude itself. Microsatellite data unveiled genetic differentiation of populations, forming two groups geographically partitioned along latitude.
CONCLUSIONS: The consistent finding of latitudinal variation across experiments suggests that both flowering onset and vernalization sensitivity in L. bienne populations are under genetic regulation and might depend on climatic cues at the place of origin. The association with climatic gradients along latitude suggests that the climate experienced locally drives population differentiation of the flowering onset and vernalization sensitivity patterns. The genetic population structure suggests that past population history could have influenced the flowering initiation patterns detected, which deserves further work.