Meeting Abstract
Streptanthus polygaloides (Brassicaceae) is an annual nickel hyperaccumulator endemic to serpentine soils in the Californian Sierra Nevada. Four morphologically and ecologically diverse morphs of S. polygaloides have been described that vary in sepal color, leaf morphology, and height, as well as geographic location. The morphs range from being widespread along northern and central California to being geographically isolated from all other morphs by approximately 100 km. To determine whether the four morphs are genetically distinct, we examined complete plastid genome sequences assembled from high-throughput sequencing data. Genomic DNA samples from eight populations of S. polygaloides (2 of each morph: yellow, purple, yellow/purple, and undulate) were sequenced on an Illumina HiSeq platform. Plastid genome sequences were assembled in an iterative fashion with contigs confirmed by mapping original reads back to intermediate stages of assembly. All eight full-length plastid genome sequences were annotated and aligned with various outgroup Brassicaceae. Maximum likelihood and Bayesian analyses were performed with multiple partitioning strategies. Phylogenetic analyses strongly support clades containing purple and undulate samples, although there is a strong geographic signal in the phylogeny overall. Numerous morph-specific plastid SNPs were identified that can be tested more widely across the S. polygaloides range with additional sampling.
