De Novo Transcriptome Sequencing in Trigonella foenum-graecum L. to Identify Genes Involved in the Biosynthesis of Diosgenin

Trigonella foenum-graecum L. (fenugreek) is a viable alternative for production of diosgenin because of its shorter growing cycle, lower production costs, and consistent yield and quality. We studied de novo transcriptome analysis along with the diosgenin pathway in Trigonella foenum-graecum and identified the genes responsible for diosgenin biosynthesis. The GMV-1 variety of Trigonella foenum-graecum has been used in the present study for transcriptome analysis by sequencing messenger ribonucleic acid (RNA) with a SOLiD 4 Genome Analyzer. Deep sequencing data of the transcriptome was assembled using various assembly tools along with functional annotation of genes, and pathway analysis for diosgenin biosynthesis was deciphered. A total of 42 million high quality reads were obtained. De novo assembly was performed using Velvet at different k-mer, Oases, and CLC Genomics Workbench, which generated 20,561 transcript contigs. CAP3 was used to reduce the redundancy of contigs obtained through these assemblers. A total of 18,333 transcript contigs were functionally annotated. Kyoto Encyclopedia of Genes and Genomes pathway mapping showed that 6775 transcripts were related to plant biochemical pathways including the diosgenin biosynthesis pathway. The large number of transcripts reported in the current study will serve as a valuable genetic resource for Trigonella foenum-graecum. Sequence information of the genes that were involved in diosgenin biosynthesis could be used for metabolic engineering of Trigonella foenum-graecum to increase diosgenin content.