Canalization of Seasonal Phenology in the Presence of Developmental Variation: Seed Dormancy Cycling in an Annual Weed
Canalization of Seasonal Phenology in the Presence of Developmental Variation: Seed Dormancy Cycling in an Annual Weed
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DOI：
10.1093/icb/icx065
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发表时间：
2017-11-01
影响因子：
2.6
通讯作者：
Donohue, Kathleen
中科院分区：
文献类型：
--
作者：
Edwards, Brianne;Burghardt, Liana T.;Donohue, Kathleen
一个生命阶段发育时间的变化可能会在代内和代际之间产生影响，从而破坏其他生命阶段的最佳物候。通过关注植物发育停滞的常见机制（种子休眠），我们研究了开花时间的变化如何影响种子发芽行为，并确定了尽管繁殖时间变化但仍可能导致渠道化发芽行为的潜在过程。我们通过实验控制种子成熟期间的温度和种子传播/埋藏的季节性时间，并通过评估季节性周期内出土种子的温度依赖性发芽，量化了繁殖时间对休眠周期的影响。我们发现，通过种子成熟温度和传播时间的繁殖时间，强烈影响种子埋藏后几周内的发芽行为。然而，在失去初级休眠并经历田间的自然温度和湿度条件后，埋藏的种子随后影响了它们的发芽行为。初级休眠完全丧失后，种子成熟和传播处理的发芽行为相似，即使诱导次级休眠也是如此。母体效应本身可能有助于发芽的渠道：首先，通过诱导秋季成熟的种子更强的休眠，其次通过改变这些种子对其周围环境的反应。休眠周期中的基因型有所不同，已知休眠基因的功能等位基因是在多年的秋季到春季温暖的温度下抑制发芽所必需的。休眠基因功能的丧失几乎消除了所有的休眠周期。总之，只有当种子保持初级休眠时，生殖物候对埋藏种子休眠周期的影响才明显，并且遗传施加的种子休眠、母体诱导的种子休眠和次级休眠的组合可以减轻生殖物候变化所造成的发芽行为的变化。
Variation in the developmental timing in one life stage may ramify within and across generations to disrupt optimal phenology of other life stages. By focusing on a common mechanism of developmental arrest in plants-seed dormancy-we investigated how variation in flowering time influenced seed germination behavior and identified potential processes that can lead to canalized germination behavior despite variation in reproductive timing. We quantified effects of reproductive timing on dormancy cycling by experimentally manipulating the temperature during seed maturation and the seasonal timing of seed dispersal/burial, and by assessing temperature-dependent germination of unearthed seeds over a seasonal cycle. We found that reproductive timing, via both seed-maturation temperature and the timing of dispersal, strongly influenced germination behavior in the weeks immediately following seed burial. However, buried seeds subsequently canalized their germination behavior, after losing primary dormancy and experiencing natural temperature and moisture conditions in the field. After the complete loss of primary dormancy, germination behavior was similar across seed-maturation and dispersal treatments, even when secondary dormancy was induced. Maternal effects themselves may contribute to the canalization of germination: first, by inducing stronger dormancy in autumn-matured seeds, and second by modifying the responses of those seeds to their ambient environment. Genotypes differed in dormancy cycling, with functional alleles of known dormancy genes necessary for the suppression of germination at warm temperatures in autumn through spring across multiple years. Loss of function of dormancy genes abolished almost all dormancy cycling. In summary, effects of reproductive phenology on dormancy cycling of buried seeds were apparent only as long as seeds retained primary dormancy, and a combination of genetically imposed seed dormancy, maternally induced seed dormancy, and secondary dormancy can mitigate variation in germination behavior imposed by variation in reproductive phenology.