Transcriptome Analysis and Identification of Genes Related to Biosynthesis of Anthocyanins and Kaempferitrin in Kenaf (Hibiscus cannabinus L.)

Kenaf is a valuable fiber and medicinal crop. Here, we performed RNA-sequencing to obtain comprehensive transcriptome information and identify putative genes involved in biosynthetic pathways of anthocyanins and kaempferitrin in kenaf. A total of 39.6 Gb reads were generated for six kenaf accessions. Individual de novo assembly of each accession and clustering of whole transcriptome contigs finally yielded 299,880 representative transcripts having an average length of 1217 bp, of which 231,825 (77.3%) were annotated against various databases. Expression profiling of the transcripts identified 6,592 differentially expressed genes (DEGs) among the three accessions, C-14 (a local landrace) and two of its mutant varieties, Jeokbong (purple leaves and stems) and Baekma (light green leaves and stems). In addition to their altered coloration, leaves of these two mutants had significantly different anthocyanin and kaempferitrin contents. We constructed anthocyanin and kaempferitrin biosynthetic pathways and identified 671 transcripts mapping to the entire pathway. In addition, 29 DEGs assigned to eight structural genes and 41 DEGs related to three transcription factor families were identified in high anthocyanin- and kaempferitrin-accumulating mutant Jeokbong. Our results provide a large transcriptome library pool for understanding gene functions and should also be useful in further studies of flavonoid biosynthesis in kenaf.