Analysis of the Flowering Regulatory Network in the Grass Brachypodium distachyon

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The initiation of flowering is a key transition in the plant life cycle. In many plant species, particularly those adapted to temperate climates, flowering occurs at a particular time of year in response to the sensing of seasonal cues such as changes in day-length and temperature. The objective of the research is to further the understanding of the genes and biochemical pathways that control the timing of flowering in response to seasonal cues in grasses, a group of plants that includes many important crops such as wheat, oats, rice, and corn. Much of the research will utilize the model grass Brachypodium distachyon because working in this species facilitates identifying the genes underlying flowering in response to seasonal cues. The data generated will help to lay the groundwork for tailoring the flowering of crop species, and will advance the basic understanding of how organisms have evolved systems to perceive environmental cues and translate those cues into developmental programs such as the initiation of flowering. This project will result in the training of graduate students and postdocs, and provide undergraduates with an opportunity to learn about research in genetics, molecular biology, and plant development while exploring their interests in a STEM career. The project will also involve development of a classroom module to provide K-12 students with an opportunity to explore how plants grow and develop and respond to seasonal signals such as the cold of winter.A major goal is to advance the understanding of how perception of winter cold as well as the short days of winter are translated into stable, epigenetic changes in gene expression that enable grasses that are adapted to temperate climates to become competent to flower in the spring when conditions are most favorable for reproduction. The process is known as vernalization. The project will involve studying certain recently discovered key genes involved in both cold-mediated and short-day-mediated flowering in grasses. These genes had not previously been known to play a role in flowering. One group of genes encodes proteins that may be part of a novel, plant-specific gene regulatory complex; another represents a new role for a member of the florigen gene family. A combination of genetics and biochemistry will be employed to explore the role of the proteins encoded by these genes with the goal of better understanding the molecular basis of how flowering is regulated in response to seasonal cues in grasses. The flowering pathways under study evolved independently in different groups of plants; thus, this research is also a model for studying how convergent evolutionary pathways can lead to a solution to the common problem of ensuring that flowering only occurs after winter has ended.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.