Effect of ploidy level on podophyllotoxin content and expression of genes related to its biosynthesis in callus cultures of Linum album

Linum album Boiss., an endemic plant of Iran, is of high medical interest due to producing podophyllotoxin (PTOX) as an anticancer and antiviral compound. Polyploidy induction is a useful approach to improve the production of secondary metabolites in medicinal plants. In this study, concerning the high value and low yield of PTOX in L. album callus culture, tetraploid callus cultures were established from in vitro-derived leaves of the induced tetraploid L. album, and their ploidy stability was confirmed by the flow cytometry after six times subculture. Tetraploid calli produced 2.1-fold more PTOX than diploid calli. The autopolyploidy led to up-regulation of key genes related to the biosynthesis of PTOX, including phenylalanine ammonia-lyase (PAL), cinnamyl-alcohol dehydrogenase (CAD), cinnamoyl-CoA reductase (CCR), and pinoresinol-lariciresinol reductase (PLR). Among these genes, the expression level of PAL gene was more affected than the other genes by doubling of ploidy level. These findings indicate that autopolyploidy could be considered as an appropriate strategy for the higher production of PTOX in L. album callus.

Automated summary

In this study, tetraploid callus cultures of Linum album, a plant endemic to Iran known for its medicinal properties, were established to increase the production of podophyllotoxin (PTOX). The tetraploid calli produced 2.1-fold more PTOX compared to diploid calli. The up-regulation of key genes involved in PTOX biosynthesis was observed in the tetraploid calli, indicating that autopolyploidy could be an effective strategy for enhancing PTOX production in L. album callus.