School of Plant Biology, The University of Western Australia, Stirling Highway, Crawley WA 6009, Australia.
Ann Bot. 2012 Jun;109(7):1369-78. doi: 10.1093/aob/mcs067. Epub 2012 Apr 3.
The smoke-derived chemical karrikinolide (KAR(1)) shows potential as a tool to synchronize the germination of seeds for weed management and restoration. To assess its feasibility we need to understand why seeds from different populations of a species exhibit distinct responses to KAR(1). Environmental conditions during seed development, known as the parental environment, influence seed dormancy so we predicted that parental environment would also drive the KAR(1)-responses of seeds. Specifically, we hypothesized that (a) a common environment will unify the KAR(1)-responses of different populations, (b) a single population grown under different environmental conditions will exhibit different KAR(1)-responses, and (c) drought stress, as a particular feature of the parental environment, will make seeds less dormant and more responsive to KAR(1).
Seeds of the weed Brassica tournefortii were collected from four locations in Western Australia and were sown in common gardens at two field sites, to test whether their KAR(1)-responses could be unified by a common environment. To test the effects of drought on KAR(1)-response, plants were grown in a glasshouse and subjected to water stress. For each trial, the germination responses of the next generation of seeds were assessed.
The KAR(1)-responses of seeds differed among populations, but this variation was reduced when seeds developed in a common environment. The KAR(1)-responses of each population changed when seeds developed in different environments. Different parental environments affected germination responses of the populations differently, showing that parental environment interacts with genetics to determine KAR(1)-responses. Seeds from droughted plants were 5 % more responsive to KAR(1) and 5 % less dormant than seeds from well-watered plants, but KAR(1)-responses and dormancy state were not intrinsically linked in all experiments.
The parental environment in which seeds develop is one of the key drivers of the KAR(1)-responses of seeds.
烟雾衍生的化学物质卡瑞醇内酯（KAR(1)）具有同步种子萌发的潜力，可用于杂草管理和生态恢复。为了评估其可行性，我们需要了解为什么来自同一物种不同种群的种子对 KAR(1)表现出不同的反应。种子发育过程中的环境条件，即亲代环境，会影响种子休眠，因此我们预测亲代环境也会影响种子对 KAR(1)的反应。具体而言，我们假设：(a) 共同的环境将统一不同种群对 KAR(1)的反应；(b) 在不同环境条件下生长的单一种群将表现出不同的 KAR(1)反应；(c) 干旱胁迫，作为亲代环境的一个特殊特征，将使种子休眠性降低，并对 KAR(1)更敏感。
从西澳大利亚的四个地点采集杂草 Brassica tournefortii 的种子，并在两个田间地点的共同花园中播种，以检验共同环境是否可以统一它们对 KAR(1)的反应。为了测试干旱对 KAR(1)反应的影响，将植物在温室中生长并进行水分胁迫处理。对于每个试验，评估下一代种子的萌发反应。
种子对 KAR(1)的反应在种群之间存在差异，但在共同环境中发育时，这种差异会减小。在不同环境中发育时，每个种群的 KAR(1)反应都会发生变化。不同的亲代环境以不同的方式影响种群的萌发反应，表明亲代环境与遗传因素相互作用，决定 KAR(1)的反应。与来自水分充足的植物的种子相比，来自干旱植物的种子对 KAR(1)的反应提高了 5%，休眠程度降低了 5%，但在所有实验中，KAR(1)反应和休眠状态并非内在相关。
种子发育的亲代环境是影响种子对 KAR(1)反应的关键因素之一。
