A Carnivorous Plant Genome: the Parallel Evolution of Digestive Enzymes

Carnivorous plants form specialized leaves that are capable of attracting, trapping, and digesting prey and absorbing nutrients. The unusual plants evolved from non-carnivorous plants but their evolutionary process is mostly unknown. The Australian pitcher plant, Cephalotus follicularis, produces both carnivorous pitcher and non-carnivorous flat leaves, enabling us to deduce carnivory-related genes by comparative approaches in a single species. To understand the genomic changes associated with the evolution of carnivory, we sequenced 2-Gbp genome of C. follicularis. Whole-genome shotgun data corresponding to 100-fold depth were produced by Illumina paired-end/mate-pair sequencing with 180-bp to 5-kb insert sizes. A de novo assembly yielded a total of 1.7 Gbp in 43,308 scaffolds with 15.6 kb of contig N50 and 83.3 kb of scaffold N50. We further produced 14 Gbp of PacBio reads with 2-kb mean max subread length for gap filling. Transcript-based gene prediction with RNA-seq reads found 45,469 gene models. Transcriptome comparison of the flat and pitcher leaves identified digestive enzyme genes that are expressed specifically in the pitcher leaves. We extended transcriptome analyses to other carnivorous plants that have different origins in their carnivory. We will discuss on the origin and evolution of digestive genes.