Abstract Detail

Evolution, Ecology, Development, And Genomics Of Carnivorous Plants

Renner, Tanya [1], Lan, Tianying [2], Rajaraman, Sitaram [3], Herrera-Estrella, Luis [4], Ibarra-Laclette, Enrique [4], Zheng, Chunfang [5], Sankoff, David [5], Schuster, Stephan [2], Jarkko, Salojarvi [2], Albert, Victor [2].

Plant carnivory and the evolution of genomic architecture in the Caryophyllales.

Recent studies of carnivorous plant genomes (1,2) have focused on genome-scale issues in the evolution of carnivory. The sequencing, assembly, annotation, and primary analysis of a high-quality, updated Utricularia gibba (humped bladderwort, Lamiales) nuclear genome based on PacBio SMRT third-generation sequencing technology permitted the assembly of several complete chromosomes and considerable repetitive DNA (~18 Mb) that had escaped the initial 82 Mb short-read assembly (3). Genome size in U. gibba is considerably reduced compared to its ancestors, but this shrinkage was not accompanied by an appreciable reduction in overall gene number. The principal cause of U. gibba's genome shrinkage was contraction of expendable non-coding DNA. This suggests that little non-coding DNAs and few mobile elements are sufficient to regulate and integrate all the processes required for the development and reproduction of a complex organism. More recently, we have expanded genome sequencing for an independent lineage of carnivorous plants, Drosera (sundews, Caryophyllales). Drosera are unusual in normally bearing holocentric chromosomes, where kinetochores attach throughout chromosome arms. We used Chicago and Dovetail Hi-C data to scaffold PacBio-Illumina draft assemblies for D. regia and D. capensis, monocentric and holocentric species, respectively. Syntenic analyses revealed no post-gamma polyploidies prior to their species split, after which an independent genome triplication occurred in D. regia, followed by a D. capensis-specific genome duplication. Among the tandemly duplicated Drosera genes, significantly enriched GO categories include defense response and secondary metabolism, a finding congruent with the hypothesis that defense-related genes have been co-opted for plant carnivory (4). To make a direct connection between genomic and regulatory evidence for carnivory, we present the results of an experimental transcriptomic study used assess the molecular diversity of genes with trap-specific expression, indicative of functions in prey digestion. We are evaluating possible genomic convergences with other carnivore species (1,2) and using the chromosomal assemblies to address the evolution of holocentricity. (1) Fukushima K, et al. "Genome of the pitcher plant Cephalotus reveals genetic changes associated with carnivory. Nature Ecology & Evolution, 2017. DOI: 10.1038/s41559-016-0059. (2) Lan T, et al. "Long-read sequencing uncovers the adaptive topography of a carnivorous plant genome. Proceedings of the National Academy of Sciences, 2017. DOI: 10.1073/pnas.1702072114. (3) Ibarra-Laclette, et al. "Architecture and evolution of a minute plant genome. Nature, 2013. DOI: 10.1038/nature12132. (4) Renner T, Specht CD. Molecular evolution and functional evolution of class I chitinases for plant carnivory in the Caryophyllales. Molecular Biology and Evolution, 2012. DOI: https://doi.org/10.1093/molbev/mss106.

1 - The Pennsylvania State University
2 - Nanyang Technological University, Singapore
3 - University of Helsinki
4 - INECOL, Mexico
5 - University of Ottawa, Canada
6 - Nanyang Technological University, Singapore

Keywords:
molecular evolution
Genomics
Carnivorous Plants
Caryophyllales
Drosera
phylogeny
Holocentric Chromosomes.

Presentation Type: Symposium Presentation
Session: SY1, Evolution, ecology, development, and genomics of carnivorous plants
Location: 107/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 10:15 AM
Number: SY1006
Abstract ID:590
Candidate for Awards:None