WINTR: Winter Transcriptome Regulation in Poplar
Chung-Jui Tsai1* (email@example.com), Wellington Muchero,2 and Priya Ranjan2
1University of Georgia and 2Oak Ridge National Laboratory
This project aims to advance understanding of how molecular control of the winter latent state is linked to perennial woody biomass productivity.
Woody biomass growth of trees comprises a significant contribution to the supply of renewable feedstocks for biofuels and biomaterials in the emerging bioeconomy. Genetic diversity in the molecular and physiological underpinnings of woody biomass growth continues to be explored for its potential adoption in tree improvement. Most of what is known about these underpinnings has come from the study of development and expansion growth during the summer or indoors. However, the woody bole of a field-grown tree is physiologically active year-round. In temperate deciduous tree species, physiological and metabolic adjustments are essential to confer winter protection in the wood-forming tissues. Mechanisms for the avoidance or tolerance of freeze-related intracellular or extracellular desiccation and for the protection and maintenance of plasma membrane and cell wall become critical.
Researchers focus on two complementary Populus experimental systems, P. trichocarpa with rich population genomic resources and the fast-growing hybrid P. tremula ´ P. alba INRA 717-1B4 (717) with proven transformation and genome editing efficiencies. A multipronged approach integrating stem RNA-Seq, genome-wide association studies (GWAS), expression quantitative trait loci (eQTL) mapping, high-precision CRISPR genome editing, and gene network modeling will be used to investigate transcriptome regulation in woody stem tissues during the winter. Of particular interest are genome duplicates that exhibit either winter-biased expression or divergent seasonal expression in both species. GWAS and eQTL predictions will be experimentally tested by CRISPR editing of coding or cis regulatory sequences for investigating their functional links to seasonal growth transitions and woody biomass accrual. Confirmed mutants will be field tested for seasonal growth transitions, transcript and metabolite profiling, and histological analysis. The transcriptomics data will feed back into regulatory network construction to improve inference of winter processes controlled by seasonal biased genes or their regulators. A key deliverable will be the contribution of winter stem transcriptomes to existing expression data obtained primarily from actively expanding tissues. The data will be integrated within the DOE Systems Biology KBase to promote further research efforts. Understanding how seasonal growth dynamics impact woody biomass productivity will offer new targets for bioenergy crop improvement.
This research was supported by the DOE Office of Science, Office of Biological and Environmental Research (BER), grant no. DE-SC0023166. Oak Ridge National Laboratory is managed by UT-Battelle, LLC for the U.S. Department of Energy under contract no. DE-AC05-00OR22725.