Abstract Detail

Comparative Genomics/Transcriptomics

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

Caught in action: Fine-scale plastome evolution in the parasitic plants of Cuscuta sect. Ceratophorae (Convolvulaceae).

Parasitic plants have reduced to completely absent reliance on photosynthesis, and are usually characterized by sweeping morphological, physiological and genomic changes. The plastid genome (or plastome) is highly conserved in autotrophic plants, and houses many such genes. This genome is thus a useful system for documenting the genomic effects of a loss of photosynthesis. Cuscuta (dodders) represents one of 13 independent transitions to a parasitic lifestyle within angiosperms. This near-cosmopolitan genus contains more than 200 obligate hemi- and holoparasitic species. 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 of evolution among closely related species of heterotrophic plants. In particular, a complex of eight or nine closely related species in Cuscuta sect. Ceratophoprae was identified by a recently conducted slot-blot hybridization survey as being of special interest because it exhibited even more rapid evolution than the rest of the genus. This species complex was near-exhaustively sampled, and their total DNA sequenced via a high-throughput approach. Complete plastid genomes were assembled and annotated for eight species in the complex. They were found to be between 61-85 kbp in length, representing a 50-60% reduction relative to plastomes from photosynthetic Convolvulaceae. Three species have a more reduced plastome than the others due to the loss of the bulk of photosynthetic genes. The plastome variation observed in our fine-scale analysis of these eight very closely-related parasitic plant species suggests a phylogenetically progressive loss of plastid genes and offers an excellent opportunity to study the reduction of plastid genomes in parasitic plants ‘caught in action’.

1 - University of Toronto Mississauga, Biology, 3359 Mississauga Road N, Dept. of Biology, Rm DV4090A/4078, Mississauga, ON, L5L1C6, Canada
2 - University Of Toronto Mississauga, Department Of Biology, 3359 Mississauga Rd, Mississauga, ON, L5L 1C6, Canada

Keywords:
Parasitic plant
Cuscuta
Convolvulaceae
plastome
Plastid
Heterotrophy.

Presentation Type: Oral Paper
Session: 21, Comparative Genomics and Transcriptomics I
Location: 102/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 8:15 AM
Number: 21002
Abstract ID:385
Candidate for Awards:Margaret Menzel Award