NSF FIBR (Frontiers in Integrative Biological Research) Flowering Time Project

To bloom or not to bloom: How do plants weigh the cues of seasonal change to time choices that are right for their climate?

Timing is everything for plants in their natural environment. For starters, they must flower during favorable seasonal conditions to reproduce successfully. To flower at the right time, plants integrate information from environmental cues such as day length, growth temperature and past winter chilling -- and different responses to these cues are favored in different climatic regions. This capacity for integration in plants illustrates an important capacity of many biological systems: the ability to assess multiple signals in responding to complex challenges.

This project will identify mechanisms underlying this intriguing capability by exploring how plants integrate environmental signals and how the genetic pathways underlying their responses evolve in different climates. The research team will examine natural genetic variation in flowering responses in the model species Arabidopsis thaliana, an annual weed closely related to crops such as canola and cabbage. The team will collect molecular, genetic and ecological data for a core set of inbred lines of Arabidopsis originating from a wide range of climates, from Mediterranean to subarctic, across the native European range of the species.

Led by evolutionary ecologist Johanna Schmitt of Brown University, the team includes molecular biologists, evolutionary geneticists, plant modelers and computer scientists. Working together, the team will dissect the molecular mechanisms underlying natural variation in environmental signal integration. Variation in specific genes that control flowering responses will be analyzed to uncover the evolutionary forces shaping genetic signaling networks. Mapping methods similar to those used to identify genes contributing to human disease will be used to test whether natural variation in these particular genes contributes to variation in flowering responses.

These experimental efforts will be complemented by powerful modeling and simulation analyses. Computer scientists will develop a model to simulate and predict how variation in these genes affects the overall pathway function and consequent flowering responses to different environments. Evolutionary ecologists will test -- at six sites in Spain, Germany, England and Finland, in collaboration with seven leading European Arabidopsis laboratories -- the prediction that geographic climate variation favors different flowering responses in different regions.The answers to these questions are important for understanding the molecular mechanisms controlling flowering responses in crops and wild plants, as well as how natural variation in these mechanisms may allow plants to inhabit diverse geographic regions and respond to ongoing climate change. This work will also shed light on the essential capacity of biological systems to respond to complex signals in making critical adjustments in patterns of behavior, development, physiology and metabolism, and other essential functions.

Lead principal investigator:
Johanna Schmitt, Brown University

Participating Researchers:
Stephen Welch, William Hsu, Sanjoy Das, Judith Roe, Kansas State University
Michael Purugganan, New York University
Richard Amasino, University of Wisconsin
Detlef Weigel, Max Planck Institute for Developmental Biology

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