2018 ASHS Annual Conference

North American beardtongue (Penstemon Mitch.) species form a diverse group that occupies a wide variety of ecological habitats and niches. With approximately 270 species, the genus spans North America, from the Arctic to the tropics, and are organized into six monophyletic subgenera, Dasanthera, Saccanthera, Cryptostemon, Dissecti, Habroanthus, and Penstemon. Due to their diverse floral and vegetative traits, beardtongues have great horticultural value, and have been utilized in several breeding programs since the early 1800’s. To assess genetic diversity of breeding stock, and to prioritize potential crosses in our breeding program, we sequenced representative species of each beard tongue subgenus, Penstemon fruticosus (Dasanthera), P. rostriflorus (Saccanthera), P. personatus (Cryptostemon), P. dissectus (Dissecti), P. cyaneus (Habroanthus), and P. palmeri (Penstemon), using the Illumina HiSeq platform (Illumina Inc., San Diego, CA). Our sequencing data, 2 x 250 pair-end reads, contained sufficient genome coverage to assemble and annotate the complete chloroplast genome (plastome) for each species. We evaluated the complete plastomes for SSRs and repetitive sequences using the programs MISA and REPuter. We also compared whole plastome Maximum Likelihood phylogeny to the rbcL gene phylogeny of 12 Lamailes species, with Solanum lycopersicum as an outgroup. Plastome lengths varied between 152,598 base pairs (bp) and 152,739 bp for P. rostriflorus and P. cyaneus respectively. The number of SSRs identified in each plastome varied between 16 and 23 for each species. The SSR nucleotide composition and location also varied between species. Repetitive sequence length for each species were also highly variable between 25 bp and 147 bp, with one repeat of over 7,000 bp in P. rostriflorus. All species had multiple palindrome and forward repeats except P. cyaneus and P. palmeri, which only had one and two forward repeats, respectively. While the phylogenetic topologies within the Plantaginaceae remained consistent, the relationships between the other species of the Lamailes order were not consistent between the plastome phylogeny and rbcL phylogeny. The complete plastome sequences have improved our understanding of the phylogenetic relations of the beardtongue subgenera over commonly used single gene phylogenies. This will help us to predict breeding success of crosses between closely related species, as well as potentially break reproductive barriers of distantly related species by first making crosses with intermediate species.