Delineating the Roles of Rising CO2 and Temperature on Flowering Time across Pre-industrial through Future Conditions

开花时间对植物的生态和进化过程有很大的影响。如果开花时间延迟，繁殖可能会不足，或者如果在生长季节结束时没有结实子，繁殖可能会失败。相反，如果过渡到开花太快，整个生长季节可能无法用于优化繁殖。因此，开花时间的变化会改变植物的生产力，破坏植物与传粉者的相互作用，并影响作物的粮食产量。气候变化预计会对植物的开花时间产生重大影响。虽然已知一些物种在上个世纪因气候变暖而提前开花，但其他物种可能更多地受到大气中二氧化碳含量上升的影响，或者两者兼而有之。人们对二氧化碳升高对开花时间影响的机制知之甚少。这可能会被证明是有问题的，因为已知超过一半的植物物种在未来50年的高二氧化碳水平下生长时，开花时间会发生重大变化。由于二氧化碳在全球范围内不断上升，这些应对措施将对全球产生影响。本研究的总体目标是更好地理解生长、生理和分子机制之间的联系，这些机制控制开花时间，以响应当前和未来时间尺度上二氧化碳和温度的上升。首席研究员将帮助在堪萨斯州劳伦斯市开发新的“西南中学花卉和食物花园”，这将是一个教育花园，学生将在气候变化情景下应用当前的种植时间适应策略，并将测量粮食产量。这将使学生能够进行动手研究，分析自己的数据，并向社区报告他们的发现。此外，这些外联工作将有助于建立一个更了解气候变化对植物影响的社会。这些努力还将促进更强大的劳动力队伍，通过加深对植物对环境的机械反应的了解，使战略能够克服气候变化对粮食生产的负面影响。本研究的目的是为了更好地了解在工业化前和未来的条件下，控制开花时间（FLT）的生长、生理和分子机制之间的联系，以应对[CO2]和温度的上升。在对野外采集的拟南芥基因型进行的初步研究中，确定了[CO2]上升是工业化前和现代条件下加速FLTs的主要驱动因素，而令人惊讶的是，更高温度的增加减少或消除了这种反应。这些是第一批描述上个世纪发生的[二氧化碳]和温度上升对FLT影响的结果。此外，在现代和未来的条件下，FLT反应的基因型之间观察到高水平的差异，如果在其他物种中也存在这种差异，将具有重大的生态和进化意义。越来越清楚的是，[CO2]和温度升高对植被覆盖度的影响不仅仅是由于对生长速率的影响。相反，生理反应和代谢物的产生可以影响影响开花基因表达的信号机制，并改变植物开花的时间和大小，以应对气候变化因素。因此，本研究采用综合的方法来确定整个植物生长、叶片水平生理和代谢物产生的上游效应如何相互作用，从而影响下游对模式植物和作物开花基因表达的影响，并最终影响FLT。通径分析用于确定最有可能影响FLT响应[CO2]和温度的因果路径。最终，在这项研究中发展起来的生理、发育和分子理解将提高预测FLT对当前和未来气候变化的响应能力。PI在指导本科生方面有着良好的记录，包括那些来自代表性不足的群体的学生，这将在整个研究过程中继续下去。

Flowering time has a large influence on ecological and evolutionary processes of plants. If flowering time is delayed, reproduction may be insufficient or may fail if seed set is not achieved by the end of the growing season. In contrast, if the transition to flowering is too rapid, the full length of the growing season may not be utilized for optimizing reproduction. As a result, shifts in flowering time can alter plant productivity, disrupt plant-pollinator interactions, and affect food production in crops. Climate change is expected to have major impacts on the flowering times of plants. While some species are known to have flowered earlier over the last century in response to warming, others may be more influenced by rising atmospheric carbon dioxide, or both factors combined. Little is known about the mechanisms that drive elevated carbon dioxide effects on flowering time. This may prove problematic, since over half of plant species are known to exhibit major alterations in flowering time when grown at elevated carbon dioxide levels predicted for 50 years into the future. Such responses will have global implications since carbon dioxide is rising across the planet. The overall goal of this research is to better understand the linkages between growth, physiological, and molecular mechanisms that control flowering time in response to both rising carbon dioxide and temperature across contemporary through future time scales. The Principal Investigator will help develop the new "Flower and Food Garden of Southwest Middle School" in Lawrence, KS, which will be an educational garden where students will apply current adaptation strategies in planting times under climate change scenarios and will measure food production. This will enable students to conduct hands-on research, analyze their own data, and report their findings to the community. Moreover, these outreach efforts will help to develop a more informed society on the effects of climate change on plants. These efforts will also promote a stronger workforce that will enable strategies to overcome the negative effects of climate change on food production through increased understanding of plant mechanistic responses to the environment.The goal of this research is to better understand the linkages between growth, physiological, and molecular mechanisms that control flowering time (FLT) in response to both rising [CO2] and temperature across pre-industrial through future conditions. In preliminary studies with field-collected genotypes of Arabidopsis thaliana, it was determined that rising [CO2] was the main driver of accelerated FLTs between preindustrial and modern conditions, while surprisingly, the addition of higher temperature reduced or eliminated this response. These are among the first results to delineate the effects of rising [CO2] and temperature that occurred over the last century on FLT. Furthermore, between modern and future conditions, high levels of variation were observed among genotypes for FLT responses, which would have major ecological and evolutionary implications if represented in other species. It is becoming increasingly clear that the influence of increasing [CO2] and temperature on FLT is not simply due to effects on growth rate. Rather, physiological responses and metabolite production can affect signaling mechanisms that influence flowering gene expression and alter the timing and size at which plants flower in response to climate change factors. Therefore, the proposed research takes an integrative approach to determine how the upstream effects of whole-plant growth, leaf-level physiology, and metabolite production interact to influence downstream effects on flowering gene expression and ultimately FLT in model plants and crops. Path analysis is used to determine the causal pathways that are most likely influencing FLT in response to [CO2] and temperature. Ultimately, the physiological, developmental, and molecular understanding developed in this research will increase the ability to predict FLT responses to contemporary and future changes in climate. The PI has a strong track-record of mentoring undergraduate students, including those from underrepresented populations, and this will continue throughout this research.