Transcriptional Response of Overexpressing Anthranilate Synthase in Rosy Periwinkle

Anthranilate synthase (AS) is a rate-limiting enzyme in the terpenoid indole alkaloid (TIA) pathway in rosy periwinkle (Catharanthus roseus), which produces the anti-cancer drugs vinblastine and vincristine. A transgenic rosy periwinkle hairy root line overexpressing an AS subunit was previously created for the overproduction of TIAs. However, both increases and decreases in TIAs were detected after overexpressing AS.

Although overexpression is targeted to one gene, it could trigger transcriptional changes that can directly or indirectly affect TIA biosynthesis. In this study, the team of Jiayi Sun from Colorado State University studied the transcriptional responses to overexpressing AS, to further understand the regulation of the TIA pathway.

Overexpression of AS in rosy periwinkle hairy roots altered the transcription of TIA pathway genes and regulators, resulting in 2,853 differentially expressed transcripts. Pathway analysis also showed alterations in many pathways, including the jasmonic acid pathway. Furthermore, many genes in overall stress response were differentially expressed after overexpressing AS.

The analysis illustrates that overexpressing AS stimulates the overall stress response and affects the metabolic networks in rosy periwinkle hairy roots. The upregulation of JA biosynthesis pathway indicates the role of JA in regulating TIA biosynthesis in AS engineered roots.

To learn more on the study, read the full article in BMC Plant Biology.