Elucidation of Geniposide and Crocin Accumulation and Their Biosysnthsis-Related Key Enzymes during Gardenia jasminoides Fruit Growth

Gardenia jasminoides fruits are extensively grown worldwide, with a large harvest, and its major medicinal ingredients are geniposide and crocins. Research on their accumulation and biosynthsis-related enzymes is rare. In this study, the accumulation of geniposide and crocin of G. jasminoides fruits at different developmental stages were clarified by HPLC. The highest cumulative amount of geniposide was 2.035% during the unripe-fruit period, and the highest content of crocin was 1.098% during the mature-fruit period. Furthermore, transcriptome sequencing was performed. A total of 50 unigenes encoding 4 key enzymes related in geniposide biosynthsis pathways were screened, and 41 unigenes encoding 7 key enzymes in the pathways of crocin were elucidated. It was found that the expression levels of differentially expressed genes of DN67890_c0_g1_i2-encoding GGPS, which is highly related to geniposide biosynthesis, and DN81253_c0_g1_i1-encoding lcyB, DN79477_c0_g1_i2-encoding lcyE, and DN84975_c1_g7_i11-encoding CCD, which are highly related to crocin biosynthesis, were consistent with the accumulation of geniposide and crocin content, respectively. The qRT-PCR results showed that the trends of relative expression were consistent with transcribed genes. This study provides insights for understanding the geniposide and crocin accumulation and biosynthsis during fruit development in G. jasminoides.