Genome Size Evolution and Dynamics in Iris, with Special Focus on the Section Oncocyclus

Abstract

Insights into genome size dynamics and its evolutionary impact remain limited by the lack of data for many plant groups. One of these is the genus Iris, of which only 53 out of c. 260 species have available genome sizes. In this study, we estimated the C-values for 41 species and subspecies of Iris mainly from the Eastern Mediterranean region. We constructed a phylogenetic framework to shed light on the distribution of genome sizes across subgenera and sections of Iris. Finally, we tested evolutionary models to explore the mode and tempo of genome size evolution during the radiation of section Oncocyclus. Iris as a whole displayed a great variety of C-values; however, they were unequally distributed across the subgenera and sections, suggesting that lineage-specific patterns of genome size diversification have taken place within the genus. The evolutionary model that best fitted our data was the speciational model, as changes in genome size appeared to be mainly associated with speciation events. These results suggest that genome size dynamics may have contributed to the radiation of Oncocyclus irises. In addition, our phylogenetic analysis provided evidence that supports the segregation of the Lebanese population currently attributed to Iris persica as a distinct species.

De novo transcriptome characterization of Iris atropurpurea (the Royal Iris) and phylogenetic analysis of MADS-box and R2R3-MYB gene families

“…To quantify the abundance of contigs assembled, the reads of the separated Iris organs were mapped to the assembled contigs, with 125,074,925 (65%) mapped reads overall, and an average of 45% reads per tissue that mapped to a unique sequence in the assembled transcriptome (Table 3 ). Low mapping rates could be due to reads belonging to sequences below the 200 bp cut-off and also, presumably, due to the complexity of the Oncocyclus irises genome that is very large and highly repetitive 62 , 63 .…”