The Physiological Basis of Natural Variation in Germination Responses of Arabidopsis Thaliana

在拟南芥和许多其他物种的生活史中，两个发育开关决定了整个生活史和随后的种群生物学：萌发开关和开花开关。 关于开花时间适应相关的基因、开花的分子遗传途径和开花时间自然变异的地理分布，我们已经知道很多。 类似的努力致力于了解发芽时间有可能提供显着的洞察适应整个生活史的时间表和人口变异的遗传基础。 因此，本研究的重点是发芽时间的遗传基础和进化生态学。 最近发现光感受器的基因家族，光敏色素，在发芽过程中具有重要的功能，这可能使它们能够调节发芽季节。 新的数据表明，光敏色素参与发芽和相反的特性：休眠。 此外，不同光敏色素对种子萌发的贡献取决于温度。 本研究将测试光敏色素是否可以通过突变体研究调节发芽温度，比较不同光敏色素突变体的基因表达，并测试发芽的自然变化是否涉及这些相同途径表达的变化。 发芽反应的自然变化的地理分析将测试自然选择的证据发芽在区域范围内。 除了测试光敏色素调节发芽的基本机制外，拟议的研究还将测试光敏色素调节发芽途径的自然变化，并测试这种自然变化是由于光敏色素调节基因表达的变化还是由于光敏色素序列本身的变化。 这些发芽反应的遗传基础和发芽变异的地理分布的研究将有助于我们理解伴随环境变化的范围扩展和分布变化的过程显着。 通过结合开花时间和发芽物候的建模，目标是预测生活史和人口统计学作为变化的环境条件的函数。 表型调查和微阵列研究的结果将提供给社区，并为未来研究发芽自然变异的遗传基础提供基础。 这项研究还支持在基因组，生理和计算技术的各个层面的国际合作和培训。

The physiological basis of natural variation in germination responses of Arabidopsis thalianaIn the life cycle of Arabidopsis thaliana and many other species, two developmental switches determine overall life history and consequent population biology: the switch to germination and the switch to flowering. Much is known about genes associated with adaptation in flowering time, molecular genetic pathways of flowering, and geographic distribution of natural variation in flowering time. Comparable effort devoted to understanding germination timing has the potential to provide significant insight into adaptation of entire life history schedules and the genetic basis of population variation. This research therefore focuses on the genetic basis and evolutionary ecology of germination timing. It has recently been found that the gene family of photoreceptors, the phytochromes, have important functions during germination that may give them the ability to regulate the season of germination. New data indicate that phytochromes are involved in both germination and its opposite trait: dormancy. Moreover, contributions of different phytochromes to germination depend on temperature. This research will test whether phytochrome can regulate the temperature of germination through mutant studies, compare gene expression in different phytochrome mutants, and test whether natural variation in germination involves variation in the expression of these same pathways. A geographic analysis of natural variation in germination responses will test for evidence of natural selection on germination on a regional scale. In addition to testing fundamental mechanisms of phytochrome regulation of germination, the proposed research will test for natural variation in the germination pathways regulated by phytochromes and test whether that natural variation is due to variation in expression of phytochrome-regulated genes or due to variation in phytochrome sequence itself. These studies of the genetic basis of germination responses and the geographic distribution of variation in germination will contribute significantly to our understanding of processes of range expansion and distributional changes accompanying environmental change. By combining modeling of flowering time and germination phenology, the goal is to predict life history and demography as a function of changing environmental conditions. Results of the phenotypic survey and microarray studies will be made available to the community and provide a foundation for future studies of the genetic basis of natural variation in germination. This research also supports international collaboration and training at various levels in genomic, physiological, and computational techniques.