Abstract Detail

Comparative Genomics/Transcriptomics

McEvoy, Susan [1], Trouern-Trend, Alexander [1], Sezen, Uzay [2], Wegrzyn, Jill [1], Swenson, Nathan [3].

Comparative genomic approaches reveal differing stress response strategies in maples.

Of the small number of maples native to North America, Acer negundo (box elder) and Acer saccharum (sugar maple) represent two contrasting species. A. negundo is a fast-growing, short-lived tree, with a wide native range, from Canada down through Mexico. It is a pioneer species that grows well in a variety of conditions, often used for rapid canopy greenery in urban environments, but it has become invasive in regions of Europe, South America, and Asia. Its invasiveness is attributed to phenotypic plasticity in growth and allocation to biomass, and differences exist between the sexes, as it is one of the few dioecious Acer. A. saccharum is a key ecological broadleaf tree native to Northeastern forests, long-lived at an average of 400 years. It requires high nutrient soils and is susceptible to increases in salinity, heavy metals, and drought. Due to soil acid deposition and resulting nutrient imbalances, compounded with additional abiotic stresses, many A. saccharum populations are affected by “maple decline”, a condition referring to crown dieback and reduction in overall health and vigor. Dieback provides a release for other species more tolerant of acidic soils, contributing to changes in forest composition. Using the first two chromosomal-length reference genomes available for North American Acer, we conducted in-depth genomic comparisons integrated with stem tissue transcriptome data from A. saccharum nutrient perturbation studies at the Hubbard Brook Experimental Forest, a Long Term Ecological Research Station. Comparative genomic approaches focused primarily on gene families contrasting in size among the available Acer genomes, associated with abiotic stress across a larger set of plant species, or rapidly expanding or contracting in A. negundo or A. saccharum. Phenotypic differences between the two Acer are reflected at the genomic level. A. saccharum is larger with more repeats, gene duplications, a large-scale inter-chromosomal translocation, and gene families enriched in a broad array of abiotic stress response-related ontologies. Expression data for this species shows trends in calcium signaling, redox processes, and hormone regulation across calcium and aluminum treatments that varies across seasons, often corresponding with expanded families that appear to represent new variants, indicating potential adaptation. Though expression data for A. negundo is lacking, noted expansions are of particular interest as this is a predominantly contracted genome with an obvious lack of stress response enrichment compared to A. saccharum. Methylation profiles underway will further add to the understanding of each species’ stress response strategies.

1 - University of Connecticut, Ecology & Evolutionary Biology, 75 N. Eagleville Road, Unit 3043, Storrs, CT, 06269-3043, United States
2 - Smithsonian Environmental Research Center, Edgewater, MD, 21037
3 - University of Notre Dame, Department of Biological Sciences, Notre Dame, IN, 46556, USA

Keywords:
maple
forest
tree
abiotic stress
calcium
genomics
soil.

Presentation Type: Oral Paper
Session: CGT3, Comparative Genomics/Transcriptomics III
Location: /
Date: Tuesday, July 20th, 2021
Time: 3:00 PM(EDT)
Number: CGT3001
Abstract ID:327
Candidate for Awards:Margaret Menzel Award