Transcriptome-Guided Mining of Genes Involved in Crocin Biosynthesis

Abstract

Gardenia jasminoides is used in traditional Chinese medicine and has drawn attention as a rich source of crocin, a compound with reported activity against various cancers, depression and cardiovascular disease. However, genetic information on the crocin biosynthetic pathway of G. jasminoides is scarce. In this study, we performed a transcriptome analysis of the leaves, green fruits, and red fruits of G. jasminoides to identify and predict the genes that encode key enzymes responsible for crocin production, compared with Crocus sativus. Twenty-seven putative pathway genes were specifically expressed in the fruits, consistent with the distribution of crocin in G. jasminoides. Twenty-four of these genes were reported for the first time, and a novel CCD4a gene was predicted that encodes carotenoid cleavage dioxygenase leading to crocin synthesis, in contrast to CCD2 of C. sativus. In addition, 6 other candidate genes (ALDH12, ALDH14, UGT94U1, UGT86D1, UGT71H4, and UGT85K18) were predicted to be involved in crocin biosynthesis following phylogenetic analysis and different gene expression profiles. Identifying the genes that encode key enzymes should help elucidate the crocin biosynthesis pathway.

Tandem gene duplications drive divergent evolution of caffeine and crocin biosynthetic pathways in plants

“…In a previous transcriptomic study [20], we identified several G. jasminoides unigenes bearing high sequence similarity to candidate genes for crocin biosynthesis (Additional file 2: Table S16). However, the low number of tissues analyzed by RNA-Seq (3 versus 7 in the present study) and the high level of fragmentation of the unigenes prevented the unambiguous identification of bona fide candidates for all the steps through coexpression analysis, as well as the expression in E. coli of the corresponding full-length proteins for functional assays.…”

“…1b). The Gardenia crocin biosynthesis pathway has not yet been elucidated, in spite of the availability of transcriptome data [20]. Two G. jasminoides UGTs, GjUGT94E5 and GjUGT75L6, are able to catalyze the two-step conversion of crocetin into crocins in vitro [21].…”

“…Two G. jasminoides UGTs, GjUGT94E5 and GjUGT75L6, are able to catalyze the two-step conversion of crocetin into crocins in vitro [21]. However, the expression profiles of the corresponding genes are not consistent with their proposed role in crocin biosynthesis in G. jasminoides fruits [20]. Additionally, the lack of genomic information for crocin-producing species hampers the elucidation of the mechanisms underlying the molecular evolution of crocin biosynthesis.…”

Genome-Wide Characterization and Analysis of bHLH Transcription Factors Related to Crocin Biosynthesis in Gardenia jasminoides Ellis (Rubiaceae)

“…Crocins have been indicated to be highly accumulated in mature G. jasminoides fruits [37]. The expression of the key enzyme genes, including GjCCD4a, GjALDH2C3, GjUGT94E13, and GjUGT74F8, in the crocin biosynthesis pathway was higher in mature fruits than in other organs.…”

De novo leaf and root transcriptome analysis to explore biosynthetic pathway of Celangulin V in Celastrus angulatus maxim

“…Thus, comprehensive genomic information can be further analyzed for gene expression, molecular mechanisms and biological pathways [17, 18]. This strategy has been efficiently used in traditional Chinese medicinal species such as Gardenia jasminoides [19], Pseudostellaria heterophylla [20], Panax notoginseng [21] and Cephalotaxus hainanensis [22].…”