As we face the twin challenges of increased population growth and climate change it is important to understand how plants can survive water stress (drought). Plants as sessile organisms have to continuously defend themselves against environmental stresses and optimal stress responses are critical for survival, reproduction and crop yield. Stress responses require reprogramming of gene expression. Additionally, gene expression changes need to be rapid and reversible. This project will investigate how the essential Polycomb gene silencing mechanism contributes to plant water stress response and whether rapid synthesis of a class of non-expressed RNA molecules directs the Polycomb silencing machinery to the appropriate genes to be silenced. The project will provide insight into how plant drought responses can be enhanced and will provide authentic research experiences for undergraduate and high school students. Undergraduate students will participate in experimental research in laboratory courses and in the research laboratory using state-of-the-art experimental approaches. Students will design experiments, implement procedures and learn to communicate about science. Formative and summative assessments will help improve the efficacy of the laboratory course. Related high school laboratory exercises will be developed and PI Wagner will give lectures and workshops to high school students about this project during summer research academies.
In recent years it has become apparent that the majority of the genome is transcribed as noncoding transcripts, the roles of which are poorly understood. RNA abundance can change more rapidly than protein abundance, making lncRNAs ideally suited to direct chromatin regulatory complexes to new sites in the genome in response to environmental cues. This project will identify lncRNAs that recruit Polycomb complexes to new loci upon water stress sensing using four complementary approaches. First, regions to which Polycomb complexes are rapidly recruited and that are silenced upon water stress sensing will be defined by genomic approaches. Second, lncRNAs that specifically associate with the Polycomb complexes in response to the stress will be identified by combined biochemical and high-throughput sequencing approaches. Third, nuclear protein-bound lncRNA will be identified whose abundance increases under stress conditions by high-throughput sequencing. Finally, Polycomb-associated lnRNAs that increase in abundance upon stress sensing will be tested for biological roles in plant stress response and in Polycomb recruitment using reverse genetic approaches. Findings from this study will significantly enhance understanding of Polycomb recruitment, lncRNA function and transcriptional reprogramming during water stress response. The results ultimately will enable us to modulate chromatin regulatory complex recruitment to enhance desirable traits in plants such as tolerance to drought and other stresses.
This project is funded by the Genetic Mechanisms Program in the Division of Molecular and Cellular Biosciences.
