Transcriptome based high-throughput SSRs and SNPs discovery in the medicinal plant Lagenaria siceraria

Abstract

<i>Lagenaria siceraria</i> (Molina) Standley has unique biological characteristics with high nutritional and medicinal values. It is an important pharmaceutical plant with various biologically active ingredients. Genetic improvement and deeper genomic studies require a rich resource of molecular markers. The application of next-generation sequencing technology, especially for transcriptome profiling, has greatly facilitated high throughput single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) discovery. In this study, we sequenced the transcriptome of three major cultivars of <i>L. siceraria</i> and obtained 64.88 GB of clean data. The assembled high-quality reads were clustered into 89,347 unigenes, which were annotated by non-redundant protein database, Swiss-Port, Eukaryotic Ortholog Groups, Kyoto Encyclopedia of Genes and Genomes, and gene ontology databases. A total of 8,891 SSR and 35,873 SNP markers were predicted from unigenes by MISA and SAM tools, respectively. Characterization of the predicted markers in <i>L. siceraria</i> showed that the SSR and SNP densities were 60 and 243 markers per Mb of genome, respectively, and the estimated ratio of transition to transversion of SNP was 2.016. These markers will be very useful for genetic studies in <i>L. siceraria</i>, especially for the high-density linkage map construction and genome-wide association studies. Further genomic studies based on these results will facilitate the identification of novel genes or alleles of pharmaceutical importance.