Abstract Detail

Comparative Genomics/Transcriptomics

Drummond, Chloe Pak [1], Bocklund, Kylie [1], Lan, Tianying [1], Tan, Qiao Wen [4], Fukushima, Kenji [5], Rajaraman, Sitaram [6], Salojärvi, Jarkko [4], Albert, Victor [1], Renner, Tanya [1].

Co-option and carnivory in the Caryophyllales.

Carnivorous plants are an ideal system for studying evolutionary transitions, as the habit evolved at least five times within flowering plants. We focus specifically on the role of genetic co-option in the evolutionary transition to plant carnivory in the Caryophyllales, and ask how this process compares across distantly-related taxa in the orders Ericales, Lamiales, and Oxalidales. In all carnivorous plants studied so far, evidence points to co-option of defense proteins for prey-responsive functions, however details concerning the origins, evolution, and mechanisms of action of relevant gene families remain poorly understood. Although substantial genomic and transcriptomic data is available for Utricularia gibba (Lamiales) and Cephalotus follicularis (Oxalidales), the availability of next-generation sequencing data for other carnivorous plant lineages has been limited. To improve resources for the carnivorous Caryophyllales, we used a Dovetail HiC with HiRise genome assembly for Drosera capensis L. (Cape sundew) to conduct reference-based RNA-seq experiments on chitin-treated plants to identify genes involved (and potentially co-opted) in carnivory. To study carnivory-related genes within a phylogenetic framework, we focused on four gene families that code for pathogenesis-related (PR) proteins identified in the digestive fluid of independent carnivorous plant lineages: chitinase, glycoside hydrolase family 17, thaumatin, and cysteine protease. For each gene family, coding sequences were mined from 20 genomes (16 non-carnivorous and 4 carnivorous) and combined with sequences derived from 4 digestive fluid proteomes. Gene family members were assigned putative functions in carnivory if annotated to have trap-specific expression, and/or were present in digestive fluid proteomes. Phylogenetic reconstructions of nucleotide and amino acid sequences revealed unexpected orthologous relationships among carnivory-related genes despite independent origins of plant carnivory, which may indicate repeated co-option of genes related by common descent. Concurrently, tandem expansions observed within all four gene families provide an additional framework for testing co-option via recruitment following lineage-specific expansion. This study provides a backdrop for more fine-scale investigation into the regulation and evolution of carnivory in the Caryophyllales.

Related Links:
http://www.cpdrummond.com

1 -
2 - The Pennsylvania State University
3 - University at Buffalo, Biological Sciences, 109 Cooke Hall, Buffalo, NY, 14260
4 - Nanyang Technological University
5 - Universität of Würzburg
6 - University of Helsinki
7 - The Pennsylvania State University, Entomology, 501 ASI Building , University Park, PA, 16802

Keywords:
carnivory
comparative genomics
Transcriptomics
Caryophyllales.

Presentation Type: Oral Paper
Session: CG1, Comparative Genetics/Genomics I
Location: Tucson I/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 10:30 AM
Number: CG1008
Abstract ID:721
Candidate for Awards:Margaret Menzel Award