Genetic and physiological mechanisms of a fitness trade-off across environments

温带的生物，当暴露在凉爽的秋季温度下时，会经历细胞和代谢的变化，从而通过冷冻提高存活率。这些反应可能会耗费大量能量，需要在未来几天到几个月内根据情况进行适当调整。太少不会为冷冻做准备，太多可能会抑制生长和繁殖。适应季节性的成本和收益之间的权衡可能会限制本地物种和作物的繁荣。气候多变性威胁到生物体“预测”未来环境的能力，并将加剧本地物种灭绝的风险和减少作物产量。然而，我们不知道大多数生物如何适应冬季，更不知道这种适应的成本。这项拟议中的研究将首次将我们对基因和新陈代谢的适应和权衡的理解与对比自然环境中的表现联系起来。该研究系统以十多年的实地实验和气候数据为基础，以及调节冷适应的基因的自然和工程变体，并被假设为在不同气候条件下生存和繁殖差异的基础。这种焦点调控基因在许多植物物种中对寒冷做出反应，驯化的成本对于本地物种的气候适应性和改进农艺品种直接重要。将为初中和高中学生开展关于生物体对气候变化的反应的更广泛的影响活动，包括一个“数据金块”模块，通过使用真实的数据回答科学问题，促进学生的定量技能。不同环境之间的适应性权衡是生物多样化的关键驱动力。最终，但尚未实现的目标，在理解适应性权衡的遗传基础是确定完整的因果链连接自然发生的序列多态性，分子和生物体表型，并在对比环境中的生物体进化的适应性。拟议的工作使用本地适应生态型的拟南芥从意大利和瑞典，其中冷驯化的耐冷冻基因座被假设为基础的遗传权衡。转录因子编码基因CBF2中天然存在的多态性被鉴定为负责主要的耐冷冻位点。拟议的实验将测试CBF2介导跨环境遗传权衡的假设，并确定发生这种情况的遗传和代谢机制。遗传原种包括在多个生态型背景中的近等基因和突变株系，其含有或模拟在意大利生态型中发现的功能cbf2等位基因的丧失。拟议的实验将量化生长速率，开花物候，终身健身，全基因组基因表达，和非靶向代谢组学在模拟自然环境的条件下。这些条件的基础上，网站一级的气候数据和概括的差异，在本地网站的生态类型的相对适合度。这是一个无与伦比的整合详细研究的遗传，分子和生理机制的适应性表型的系统与广泛的信息，在本地环境中的适应。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Organisms in temperate zones, when exposed to cool autumn temperatures, undergo cellular and metabolic changes which increase survival through freezing. These responses are likely to be energetically costly, requiring appropriate adjustments for conditions days to months in the future. Too little will not prepare for freezing, too much may inhibit growth and reproduction. The trade-off between the costs and benefits of adaptation to seasonality can limit where native species and crops can thrive. Climatic variability threatens the capacities of organisms to “predict” the future environment and will contribute to extinction risks for native species and reduced crop production. Yet, we do not know how most organisms acclimate for winter, and even less about the costs of such acclimation. The proposed research will, for the first time, connect our understanding of adaptation and trade-offs from genes and metabolism to performance in contrasting natural environments. The study system has a foundation of over a decade of field experimental and climate data, and both natural and engineered variants of a gene that regulates cold acclimation and is hypothesized to underlie differences in survival and reproduction across contrasting climates. This focal regulatory gene responds to cold in many plant species, and the costs of acclimation are directly important for climate resilience of native species and for improving agronomical varieties. Broader impact activities for middle and high school students on organismal responses to climate change will be developed, including a “Data Nugget” module to promote students’ quantitative skills by answering scientific questions using real data. Fitness trade-offs across environments are key drivers of biological diversification. The ultimate, but yet unrealized, goal in understanding the genetic basis of fitness trade-offs is to identify the full causal chain connecting naturally occurring sequence polymorphisms, molecular and organismal phenotypes, and fitness in the contrasting environments in which the organisms evolved. The proposed work uses locally adapted ecotypes of Arabidopsis thaliana from Italy and Sweden, for which cold-acclimated freezing tolerance loci are hypothesized to underlie genetic trade-offs. A naturally occurring polymorphism in a transcription factor encoding gene CBF2 was identified as responsible for a major freezing tolerance locus. The proposed experiments will test the hypothesis that CBF2 mediates a genetic trade-off across environments, and determine the genetic and metabolic mechanisms by which this occurs. Genetic stocks include Near Isogenic and mutant lines in multiple ecotypic backgrounds that contain, or mimic, the loss of function cbf2 allele found in the Italian ecotype. Proposed experiments will quantify growth rates, flowering phenology, lifetime fitness, genome-wide gene expression, and untargeted metabolomics in conditions simulating the natural environments. These conditions are based on site-level climate data and recapitulate differences in relative fitness of the ecotypes at the native sites. This is an unparalleled integration of detailed studies of the genetic, molecular, and physiological mechanisms of an adaptive phenotype in a system with extensive information about local adaptation in the native environments. Training will be provided for undergraduates and postgraduates who will also participate in education outreach activities with middle and high school students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.