De Novo assembly, characterization and development of EST-SSRs from Bletilla striata transcriptomes profiled throughout the whole growing period

PLoS One. 2018 Oct 26;13(10):e0205954. doi: 10.1371/journal.pone.0205954. eCollection 2018.

Abstract

Bletilla striata is an endangered orchid that has been used for millennia as a medicinal herb, in cosmetics and as a horticultural plant. To construct the first nucleotide database for this species and to develop abundant EST-SSR markers for facilitating further studies, various tissues and organs of plants in the main developmental stages were harvested for mRNA isolation and subsequent RNA sequencing. A total of 106,054,784 clean reads were generated by using Illumina paired-end sequencing technology. The reads were assembled into 127,261 unigenes by the Trinity package; the unigenes had an average length of 612 bp and an N50 of 957 bp. Of these unigenes, 67,494 (51.86%) were annotated in a series of databases. Of these annotated unigenes, 41,818 and 24,615 were assigned to gene ontology categories and clusters of orthologous groups, respectively. Additionally, 20,764 (15.96%) unigenes were mapped onto 275 pathways using the KEGG database. In addition, 25,935 high-quality EST-SSR primer pairs were developed from the 15,433 unigenes by MISA mining. To validate the accuracy of the newly designed markers, 87 of 100 randomly selected primers were effectively amplified; 63 of those yielded PCR products of the expected size, and 25 yielded products with significant amounts of polymorphism among the 4 landraces. Furthermore, the transferability test of the 25 polymorphic markers was performed in 6 individuals of two closely related genus Phalaenopsis and dendrobium. Which results showed a total of 5 markers can successfully amplified among these populations. This research provides a comprehensive nucleotide database and lays a solid foundation for functional gene mining and genomic research in B. striata. The developed EST-SSR primers could facilitate phylogenetic studies and breeding.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Expressed Sequence Tags / metabolism*
  • Gene Ontology
  • Genetic Markers
  • Metabolic Networks and Pathways / genetics
  • Microsatellite Repeats / genetics*
  • Molecular Sequence Annotation
  • Open Reading Frames / genetics
  • Orchidaceae / genetics*
  • Orchidaceae / growth & development*
  • Reproducibility of Results
  • Sequence Analysis, RNA
  • Transcriptome / genetics*

Substances

  • Genetic Markers

Grants and funding

The authors acknowledge the financial support of the National Natural Science Foundation of China (31560079, 31560102), the Chinese Scholarship Council (201408525081), the Scientific Project of Guizhou Province (QKH-ZY[2013]3002, QKH-LH[2014]7549), the Talents Promotion Project of Zunyi Medical University, and the 15851 Talent Project of Zunyi City (201424). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.