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Abstract Detail

Comparative Genomics/Transcriptomics

Hofford, Nate [1], Motley, M'Kayla [2], McKain, Michael [3].

Transcriptional variation across geographically disparate accessions of the invasive species Johnsongrass (Sorghum halepense).

Johnsongrass (Sorghum halepense (L.) Pers.) is a globally invasive weed that causes millions of dollars in agricultural damage and negatively impacts native biodiversity. Within the United States, Johnsongrass is widespread, and numerous studies have demonstrated ecotypic variation across its invasive range. Relatively few studies, however, have delved into the genomic basis for these differences. Johnsongrass is an allotetraploid formed from an ancient hybridization event between S. bicolor (L.) Moench and S. propinquum (Kunth) Hitchc. and subsequent whole genome duplication. The ongoing process of fractionation after a polyploid event can result in novel combinations and interactions amongst paralogs across lineages and populations. The presence-absence variation of paralogs can lead to novel expression patterns and likely influences adaptation to novel habitats in the invasive range of Johnsongrass. Our study seeks to assess transcriptional variation between geographically disparate populations focusing on the contribution of different paralogs from the S. bicolor and S. propinquum subgenomes. Four individuals from across the invasive range of Johnsongrass (OH, TX, AL, PA) were grown under standard greenhouse conditions. Using mRNA extracted from leaf tissues samples per specimen,  we constructed transcriptome libraries and sequenced them to a depth of 20 million 150 bp Illumina read pairs. We then de novo assembled transcriptomes and estimated gene expression levels for each sample. Transcripts were grouped into gene families along with gene models from multiple Sorghum bicolor accessions, maize, and Setaria italica (L.) P. Beauvois. Gene family phylogenies were reconstructed and paralogs were identified when possible. Relative expression between paralogs for each gene family was scored. Using this approach, we demonstrate variation in paralog expression across sampled populations of Johnsongrass. We explore the relative variation of paralog usage in northern (OH and PA) versus southern (AL, AZ, and TX) populations to identify potential trends associated with adaptation to colder climates. Our study represents a novel exploration of gene expression and usage in Johnsongrass, potentially informing previously observed phenotypic and ecological differences in natural populations. Future work will characterize differential expression across different tissue types and include additional populations across Johnsongrass' range.

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1 - University Of Alabama, Biology, 530 18th Street, Unit 206, Tuscaloosa, AL, 35401, United States
2 - 1900 Rice Mine Rd N Apt 320, Unit 320, Tuscaloosa, AL, 35406, United States
3 - University Of Alabama, 411 Mary Harmon Bryant Hall, Tuscaloosa, AL, 35487, United States

invasive species
subgenome dominance

Presentation Type: Poster
Session: P1, Comparative Genomics/Transcriptomics Posters
Location: Virtual/Virtual
Date: Monday, July 19th, 2021
Time: 5:00 PM(EDT)
Number: P1GT009
Abstract ID:894
Candidate for Awards:None

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