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Abstract Detail

Comparative Genomics/Transcriptomics

Banerjee, Arjan [1], Stefanovic, Sasa [2].

Plastome evolution in Cuscuta subg. Grammica (Convolvulaceae).

Parasitic plants have reduced to completely absent ability to conduct photosynthesis, and are usually characterized by sweeping morphological, physiological, and genomic changes compared to their autotrophic relatives. The plastid genome (or plastome) is highly conserved in autotrophic plants and houses many key photosynthetic genes. This molecule is thus a useful system for documenting the genomic effects of a loss of autotrophy. Cuscuta (dodders) represents one of 12 independent transitions to a parasitic lifestyle within angiosperms. This near-cosmopolitan genus contains more than 200 obligate parasitic species circumscribed in four subgenera: Grammica, Pachystigma, Cuscuta, and Monogynella. Because plastomes in this group have been reported to show a substantial degree of diversification in terms of length and gene composition, they present an opportunity for fine-scale comparisons among closely related species of parasitic plants. In addition, with respect to photosynthesis, Cuscuta is a heterogenous group containing both hemi- and holoparasitic members that are, respectively, partially or entirely reliant on parasitism to meet their carbon budget. Moreover, Cuscuta subgenus Grammica, which contains ~150 species and accounts for most of the generic plastome diversity, is similarly heterogenous with plants that retain some ability to photosynthesize present alongside completely nonphotosynthetic species. Thus, Grammica presents a tractable system for comparative plastome research where we can observe the patterns of evolution due to a transition from an autotrophic to a heterotrophic lifestyle in a group of closely related species.
In our current research, we compare and contrast plastid genomes across the phylogenetic backbone of Cuscuta subgenus Grammica to identify the changes in sequence composition and structure that have occurred as these plants have evolved along the trophic spectrum. By utilizing whole-plastome assemblies from at least one representative of each of the 15 sections that comprise the subgenus, we are able to phylogenetically triangulate the positions of genomic changes and to construct a step-by-step model of plastome evolution in these plants.

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1 - University of Toronto, Ecology and Evolutionary Biology, 25 Willcocks Street, Toronto, ON, M5S3B2, Canada
2 - University Of Toronto Mississauga, Department Of Biology, 3359 Mississauga Rd, Mississauga, ON, L5L 1C6, Canada

parasitic plants

Presentation Type: Oral Paper
Session: CGT1, Comparative Genomics/Transcriptomics I
Location: /
Date: Tuesday, July 20th, 2021
Time: 11:45 AM(EDT)
Number: CGT1008
Abstract ID:249
Candidate for Awards:Margaret Menzel Award

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