Abstract Detail

Comparative Genomics/Transcriptomics

Frangione, Erika [1], Stefanović, Saša [2].

Comparative Transcriptomics of Repeated Reticulate Evolution in the Genus Cuscuta (Convolvulaceae).

Polyploidy is known to have a strong influence on the rapid evolution observed in angiosperms due to its ability to spark near instantaneous divergence among species, including in sympatry. Notably, allopolyploidy leads to speciation because allopolyploids can fill new ecological niches and thrive better in unfavourable environments compared to their diploid parents due to their increased genetic variation. In plants, species in close contact will repeatedly hybridize and form identical allopolyploids of independent origin. Examples of recurrent hybridization beg the broader question: are some elements of evolution randomly repeated, or are they somehow canalized, leading to broad, repetitive evolutionary trajectories? Studies across plants, animals, and fungi have documented patterns in gene expression during hybridization events. Thus, it may be possible that some aspects of recurrent hybridization are intrinsic and predictable as opposed to being stochastic. One such system that describes a case of natural, recurrent hybrid formation from the same progenitors was identified in Cuscuta (Convolvulaceae). This genus is comprised of ~200 parasitic plants species with a wide geographic distribution. Our study system, C. section Denticulatae, involves two diploid progenitor species, C. denticulata and C. nevadensis, and two relatively recently formed allotetraploids, C. veatchii and C. psorothamnensis. Within the parent C. denticulata, autotetraploid populations have also been identified. All hybrids in this section appear to have undergone a host shift, leading to increased host specificity compared to their diploid parents. We will discuss our research progress in assembling and annotating transcriptomes for the two progenitor species identified within the system. These reference transcriptomes are sequenced using a next-generation RNA sequencing approach and analyzed for differentially expressed genes within each parent, including between diploid and autotetraploid individuals to investigate the effects of gene dosage (number of gene copies) on gene expression. In addition, comparative transcriptomics techniques are being used to identify and analyse potential orthologues between parents. Building on these foundations, future studies will be able to map the homeologous genes following hybridization in C. veatchii and C. psorothamnensis to the parental transcriptomes, and search for changes in post-polyploidization gene expression between them.

1 - University of Toronto Mississauga, Department of Ecology and Evolutionary Biology, 3359 Mississauga Rd, DV 4090A, Mississauga, ON, L5L 1C6, Canada
2 - University Of Toronto Mississauga, Department Of Biology, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6, Canada

Keywords:
Transcriptome
hybrid
Polyploid
Next Generation Sequencing
Cuscuta.

Presentation Type: Oral Paper
Session: CG2, Comparative Genetics/Genomics II
Location: Tucson I/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 4:30 PM
Number: CG2011
Abstract ID:458
Candidate for Awards:Margaret Menzel Award