Transcriptome characterization and screening of molecular markers in ecologically important Himalayan species (Rhododendron arboreum)

Abstract

Rhododendron arboreum is an ecologically prominent species, which also lends commercial and medicinal benefits in the form of palatable juices and useful herbal drugs. Local abundance and survival of the species under a highly fluctuating climate make it an ideal model for genetic structure and functional analysis. However, a lack of genomic data has hampered additional research. In the present study, cDNA libraries from floral and foliar tissues of the species were sequenced to provide a foundation for understanding the functional aspects of the genome and to construct an enriched repository that will promote genomics studies in the genera. Illumina’s platform facilitated the generation of ∼100 million high-quality paired-end reads. De novo assembly, clustering, and filtering out of shorter transcripts predicted 113 167 non-redundant transcripts with an average length of 1164.6 bases. Of these, 71 961 transcripts were categorized based on functional annotations in the Gene Ontology database, whereby 5710 were grouped into 141 pathways and 23 746 encoded for different transcription factors. Transcriptome screening further identified 35 419 microsatellite regions, of which, 43 polymorphic loci were characterized on 30 genotypes. Seven hundred and nineteen transcripts had 811 high-quality single-nucleotide polymorphic variants with a minimum coverage of 10, a total score of 20, and SNP% of 50.