PI: Stacey Harmer (University of California-Davis) Co-PI: Ben Blackman (University of Virginia)
Plants optimize their use of local resources by synchronizing their growth with day/night cycles, resulting in daily rhythms in leaf, stem, and root growth. This coordination is accomplished through an intricate interplay between the light signaling, circadian clock, and hormone signaling networks. However, the manner in which these networks interact to control plant growth is poorly understood. This project exploits the robust ability of sunflower to track the sun to characterize pathways that coordinate plant growth with daily environmental fluctuations. First, developmental and environmental factors that control solar tracking will be defined. Next, high-throughput analysis of hormone and gene transcript levels in different portions of solar tracking stems will be carried out, allowing the identification of candidate genes and pathways controlling these growth rhythms. Finally, genome-enabled association and linkage mapping techniques will take advantage of the abundant natural variation present in common sunflower and its wild relatives to provide essential information about the role of solar tracking in plant adaptation to the environment. Together, these studies will elucidate the interactions between diverse signaling networks that optimize plant growth with environmental changes and provide insights into ways to improve plant performance.
Plant yield is enhanced by daily growth patterns of stems and leaves that allow more efficient photosynthesis and higher water use efficiency. Although a number of molecular pathways that regulate plant growth have been identified, an understanding of how they are coordinated with each other and with environmental cues remains elusive. Solar tracking in sunflower is an extremely appropriate trait for addressing these basic questions since it provides a unique entry point to determine how internal and external cues regulate growth across a single organ. By asking fundamental questions about how this coordination occurs and evolves, these studies will reveal important insights into how to enhance crop plant performance and conserve plant diversity in the face of global climate change and an increasing human population. In addition, this project will generate extensive resources that will be useful to the entire Compositae community. To provide public access to these resources, transcriptome and functionally annotated marker data will be deposited in public databases including the NCBI Short Read Archive (www.ncbi.nlm.nih.gov/sra/), the Compositae Genome Project (http://compgenomics.ucdavis.edu/), the Sunflower Genome Resources Consortium (www.sunflowergenome.org), and DRYAD (http://datadryad.org/). Germplasm will be deposited with the National Plant Germplasm System (www.ars-grin.gov/npgs/). A student crowd-sourcing method will be developed for the analysis of time-lapse videos of plants grown in natural and controlled environments. This image analysis software developed with the iPlant Collaborative will be made freely available via the iPlant Phytobisque web portal (https://pods.iplantcollaborative.org/wiki/display/ipg2p/PhytoBisque). Finally, cross-disciplinary training in genomic, ecological, and quantitative approaches will be provided for the undergraduate and graduate students and post-doctoral fellows involved in these studies.
