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

University Of Kansas Center For Research Inc, Lawrence KS

Investigators

Abstract

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.