De novo Transcriptome Assembly and Comprehensive Annotation of Two Tree Tomato Cultivars (<i>Solanum betaceum</i> Cav.) with Different Fruit Color

Abstract

The tree tomato (Solanum betaceum Cav.) is an underutilized fruit crop native to the Andean region and phylogenetically related to the tomato and potato. Tree tomato fruits have a high amount of nutrients and bioactive compounds. However, so far there are no studies at the genome or transcriptome level for this species. We performed a de novo assembly and transcriptome annotation for purple-fruited (A21) and an orange-fruited (A23) accessions. A total of 174,252 (A21) and 194,417 (A23) transcripts were assembled with an average length of 851 and 849 bp. A total of 34,636 (A21) and 36,224 (A23) transcripts showed a significant similarity to known proteins. Among the annotated unigenes, 22,096 (A21) and 23,095 (A23) were assigned to the Gene Ontology (GO) term and 14,035 (A21) and 14,540 (A23) were found to have Clusters of Orthologous Group (COG) term classifications. Furthermore, 22,096 (A21) and 23,095 (A23) transcripts were assigned to 155 and 161 (A23) KEGG pathways. The carotenoid biosynthetic process GO terms were significantly enriched in the purple-fruited accession A21. Finally, 68,647 intraspecific single-nucleotide variations (SNVs) and almost 2 million interspecific SNVs were identified. The results of this study provide a wealth of genomic data for the genetic improvement of the tree tomato.

Keywords

• de novo transcriptome assembly
• emerging crop
• functional annotation
• molecular markers
• RNA-Seq
• Solanaceae