Single Nucleotide Polymorphism Discovery and Probe Design Using RNA-Seq and Targeted Capture in Tropical and Subtropical Pine Species.

JACKSON, COLIN ALAN. Single Nucleotide Polymorphism Discovery and Probe Design Using RNA-Seq and Targeted Capture in Tropical and Subtropical Pine Species (Under the direction of Dr. Juan Jose Acosta and Dr. Fikret Isik). Mexico and Central America are two primary pockets of diversity for tropical and subtropical pine species. Of the species found there, many are considered threatened or endangered, which in turn has spurred conservation efforts and the establishment of landrace populations for commercial use across South America and Southern Africa. The development of genomic resources in Pinus taeda has created a platform to extend these technologies into tropical pines. The information gained from these resources will prove to be valuable for the continued improvement of pure and hybrid breeding populations, as well as gene conservation efforts. In this study, we performed targeted genome and gene-based SNP discovery for the development of a high-throughput genome-wide genotyping array for tropical pines. Pooled RNA-Seq data was generated from shoot tissues of seedlings from five species: Pinus patula, Pinus tecunumanii, Pinus oocarpa, Pinus greggii and Pinus maximinoi. Pooled RNA was isolated in triplicate from 8 to 16 seedlings from two or more families per species. Paired-end RNA sequencing generated between 29.4 and 67.7 million raw reads per pool. Reads were trimmed and mapped to each species’ respective transcriptome assembly. SNP detection was performed under standard and strict criteria using a min-alternative-fraction of ≥ 0.05. Using standard criteria, we identified between 687K and 1.3M transcriptome-based SNPs per species, while strict calls produced between 426K and 824K SNPs per species. SNP probe design (using Affymetrix design criteria) resulted in 113K to 186K candidate probes per species for a total of 803K probes designed. Probes were further assessed for unique vs. repetitive mapping against the v2.01 P. taeda genome assembly. Of the 803K probes that mapped to the genome, 60% to 67% mapped uniquely in the reference genome assembly. In addition, targeted sequence data for the five species mentioned above, plus Pinus caribaea, was generated using a custom set of 40K capture probes (RAPiD Genomics Gainesville, FL). About 30K were designed from single copy regions of the v2.01 P. taeda genome and 10K were designed from P. patula and P. tecunumanii transcriptome assemblies. Across the six species, a total of 81 pooled samples were sequenced. Each pooled sample contained DNA from 4 to 8 trees from a single provenance. The 81 provenances cover the natural range of the six species in Mexico and Central America. Capture-seq analysis generated between 3.1 and 7.7 million reads per sample with 20-30X coverage of each capture region. We identified a total of 1.3 million SNPs suitable for probe design, from which, 562K probes were successfully designed. Between the two datasets, there are ~1.6 million unique locations represented by ~1 million probes. This study shows that RNA-Seq and targeted capture sequencing are valuable technologies in identifying variation within non-model species and produce a high quality dataset for implementation of probe design for use on a commercial genotyping array. © Copyright 2019 by Colin Alan Jackson All Rights Reserved Single Nucleotide Polymorphism Discovery and Probe Design Using RNA-Seq and Targeted Capture in Tropical and Subtropical Pine Species by Colin Alan Jackson A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Master of Science Forestry and Environmental Resources Raleigh, North Carolina 2019