Genomic Science Program
U.S. Department of Energy | Office of Science | Biological and Environmental Research Program

Transgenic Perturbation of Winter-Biased Genes in Populus

Authors:

Mahdi MoradPour* (mahdi.moradpour@uga.edu), Audrey Widmier, Trevor Tuma, Chen Hsieh, Ran Zhou, Brent Lieb, C.J. Tsai

Institutions:

Warnell School of Forestry and Natural Resources, Department of Genetics; Department of Plant Biology, University of Georgia–Athens

Goals

To unravel the molecular mechanisms underlying winter maintenance in temperate deciduous tree species and their impact on woody biomass productivity, thereby advancing bioenergy crop improvement.

Abstract

Dormant seasons constitute up to half the lifespan of woody perennial crops in temperate climates. While numerous studies have explored the seasonality of vegetative and floral buds, research investigating wood growth in these trees is primarily conducted in the greenhouse or during the summer season. Understanding maintenance and protection of wood-forming tissues during dormant seasons is crucial for improving stress resilience in the face of climate change. Researchers conducted seasonal transcriptome profiling of xylem tissues from mature Populus deltoides and young P. tremula x P. alba INRA 717-1B4 (717) trees. Self-organizing map (SOM) clustering analysis identified gene clusters that display season-specific expression patterns. Summer-based genes showed Gene Ontology (GO) enrichment associated with cell wall biogenesis as would be expected, whereas genes upregulated during the dormant season are associated with vital mechanisms for winter survival. These mechanisms encompass diverse aspects, including cold tolerance, cryoprotectant synthesis, cell membrane stability and integrity, metabolic adjustments, stress response, cell wall modification, growth regulation, various transport processes, and chromatin remodeling.

CRISPR-Cas9 is used to target winter-biased genes for knock-out in poplar 717 in order to characterize their functions. Candidate genes selected to date are mainly involved in the metabolism and transport of carbohydrates, which play a key role in antifreeze, dehydration protection, and spring regrowth. Other candidates are involved in nutrient transport and regulation, and protein modification and turnover. Knock-out mutants will be monitored for seasonal phenology during field trials. A subset of knockout lines will be subject to metabolomic and transcriptomic profiling. Network analysis will be used to investigate disrupted pathways and ultimately the molecular processes underlying winter maintenance and protection.

Funding Information

This research was supported by the DOE Office of Science, BER program, grant no. DE-SC0023166. Oak Ridge National Laboratory is managed by UT-Battelle, LLC for the DOE under contract no. DE-AC05-00OR22725.