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

温带地区的生物，当暴露在凉爽的秋季温度下时，会经历细胞和代谢的变化，从而通过冷冻增加生存。这些应对措施可能在能量上代价高昂，需要根据未来几天到几个月的情况进行适当调整。太少将不准备冷冻，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在哪里茁壮成长。气候变化威胁到生物“预测”未来环境的能力，并将导致本地物种灭绝和作物减产的风险。然而，我们不知道大多数生物是如何适应冬季的，更不知道这种适应的成本。这项拟议的研究将首次将我们对适应和权衡的理解从基因和新陈代谢到不同自然环境下的表现联系起来。该研究系统的基础是十多年的野外实验和气候数据，以及一种调节冷适应的基因的自然和工程变体，该基因被假设是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，驯化成本对本地物种的气候适应能力和农艺品种的改良直接重要。将为初中生和高中生开展更广泛的影响活动，以应对气候变化，包括一个“数据块”模块，通过使用真实数据回答科学问题来提高学生的定量技能。不同环境的健康权衡是生物多样化的关键驱动因素。理解适应度权衡的遗传基础的最终但尚未实现的目标是确定连接自然发生的序列多态性、分子和生物体表型以及生物体在不同环境中进化的适应度的完整因果链。该研究使用了来自意大利和瑞典的拟南芥的本地适应性生态型，假设其冷适应性抗冻基因座是遗传权衡的基础。在编码基因CBF2的转录因子中自然发生的多态性被确定为主要的抗冻基因座。拟议的实验将验证CBF2介导跨环境遗传权衡的假设，并确定这种情况发生的遗传和代谢机制。遗传资源包括多个生态型背景的近等基因和突变系，包含或模仿意大利生态型中发现的cbf2等位基因功能丧失。拟议的实验将在模拟自然环境的条件下量化生长速度、开花物候、终生适应度、全基因组基因表达和非靶向代谢组学。这些条件是基于地点水平的气候数据，并概括了原生地生态型相对适合度的差异。这是对适应性表型的遗传、分子和生理机制的详细研究的无与伦比的整合，在一个系统中有关于本地环境适应的广泛信息。为本科生和研究生提供培训，他们还将参加初高中学生的教育推广活动。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识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.