Plant steroid hormones called Brassinosteroids (BRs) signal to regulate plant growth, development and response environmental stresses. However, our understanding of how this steroid hormone controls thousands of genes to regulate these processes is incomplete. The project will generate and use multiple large-scale datasets to model how genes are controlled to govern BR-regulated growth and drought responses. BR pathways are well conserved among Arabidopsis and crop plants such as maize, rice and other crops, so the knowledge obtained from the proposed studies can be used to design strategies to optimize plant growth and crop production under drought conditions. Moreover, the project provides excellent training opportunities for graduate students and postdoctoral associates in modern plant biology. The investigators will also achieve societally relevant outcomes by providing training opportunities to underrepresented undergraduates through the George Washington Carver Internship program as well as engaging high school and community college teachers via summer internships. Through this partnership with teachers a learning module on BR-regulation of plant growth will be developed for high-school and community college students. Furthermore, unpublished data from the proposed studies will be incorporated into an upper level undergraduate course on functional genomics, systems, and network biology, freeing students to generate their own hypotheses during a group project rather than simply reproducing published work. Finally, the investigators will provide resources to the research community by organizing a workshop on plant phenomics, proteomics and computational modeling approaches and by making the data generated publicly accessible through publications and the Principal Investigator's laboratory website.
Molecular genetic studies in Arabidopsis have greatly advanced our understanding of the BR signaling pathway. BRs signal to regulate BES1/BZR1 family transcription factors (TFs), hundreds of BR-Related Transcription Factors (BR-TFs) and thousands of target genes. Although numerous BR-TFs have been identified, the transcriptional complexes that allow BES1/BZR1 and these BR-TFs to regulate the large number of BR-responsive genes have not been characterized. In addition, modeling of BR networks has proven to be a powerful approach to understand how BES1 directs a network controlling thousands of BR responsive genes. However, previously constructed BR networks have only considered transcription, overlooking important regulation at the post-transcriptional and post-translational level. The project will use an integrated genetics, genomics, and proteomics approach to establish and experimentally test a comprehensive Arabidopsis Gene Regulatory Network (GRN) governing BR-regulated growth and drought responses. By combining cutting-edge proteomics with advanced predictive modeling the project will generate a comprehensive view of BR-mediated transcriptional regulation and allow for the identification of novel factors involved in BR responses. First, investigators will uncover the components and functions of BR transcription factor complexes by examining the role of two novel BR-TFs. These two BR-TFs interact with BES1, a master regulator of the BR pathway, as well as a large number of other BR-TFs, likely forming large transcriptional complexes to control the expression of BR target genes. Second, investigators will generate BR transcriptome, proteome, and phosphoproteome datasets that are a prerequisite for a novel approach pioneered by the Co-Principal Investigator to construct GRNs based on these combined omics data. These combined networks have increased predictive ability compared to networks based only on transcriptional data and will provide a vital resource, allowing for a more complete understanding of the transcriptional program through which BRs control plant growth and stress responses.
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.
