Abstract
Paris polyphylla var. yunnanensis is an endangered herbaceous plant accumulating polyphyllins, which are widely used in clinical treatment in China. The genes involved in the biosynthesis of polyphyllins are often mixed with other steroids biosynthetic genes, forming a very complex biosynthetic network. The lack of genomic data and tissue specificity of genes makes it extremely difficult to study the biosynthetic pathway of polyphyllins. Here we report an effective method for predicting key genes of polyphyllins biosynthesis. Eight different organs were selected for metabolic analysis and transcriptome sequencing using both of PacBio and Illumina platform generating a total of 370 G of pure data, and two OSCs, 216 CYPs, and 199 UGTs were annotated. By constructing phylogenetic trees, we screened out 60 and 57 candidate genes in the CYP72, CYP90, CYP94 families of CYPs and group D of UGTs, respectively. Metabolic analysis indicates cholesterol, diosgenin, and polyphyllins et al. key metabolites varied in different selected oragns. Three modules were identified by metabolite and gene weighted co-expression network analysis, from which 41 candidate CYPs and 47 candidate UGTs were identified. Combined above information, we narrowed the candidate range of OSC, CYP and UGT genes to 2, 15 and 20. Beside three previous characterized CYPs, we also identified the OSC involved in the synthesis of diosgenin and the glycosyltransferase at the C-3 position of diosgenin for the first time in P. polyphylla. This study provides a new idea for the study of gene cluster deficiency biosynthesis pathways in medicinal plants.
Competing Interest Statement
The authors have declared no competing interest.