Transcriptome analysis for identification of indigo biosynthesis pathway genes in Polygonum tinctorium

Indigo is the most important blue dye for textile dyeing and is biosynthesized in Polygonum tinctorium. Some biochemical studies related to biosynthesis are available. However, genomic and transcriptome studies have not received sufficient attention. Here, we report de novo assembly of transcriptome datasets and its comprehensive analysis. A total of 60,395 unigenes were annotated using BLAST search against the different databases. At least 23,721 unigenes mapped onto different pathways using KEGG database. We found that 3,323 genes are involved in biosynthesis of secondary metabolites, 117 phenylalanine, tyrosine and tryptophan biosynthesis and 147 tryptophan metabolisms. Apart from this, indigo biosynthesis pathway genes viz., dioxygenase, monooxygenase, and glucosyltransferase have also been identified. Fourteen genes encoding cytochrome P450 monooxygenase, 26 glucoside dioxygenase, 9 UDP-glucose D-glucosyltransferase and 52 were β-D-glucosidase. These findings provide a foundation for further analysis of this pathway with potential to enhance the synthesis of indican in P. tinctorium.