Engineering overexpression of ORCA3 and strictosidine glucosidase in Catharanthus roseus hairy roots increases alkaloid production

• Published in: Protoplasma Vol. 253; no. 5; pp. 1255 - 1264
• Main Authors: Sun, Jiayi, Peebles, Christie A. M.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01-09-2016; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Catharanthus - genetics; Catharanthus - metabolism; Cell Biology; Gene Expression Regulation, Plant; Glucocorticoids - pharmacology; Glucosidases - genetics; Glucosidases - metabolism; Life Sciences; Original Article; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - genetics; Plant Roots - metabolism; Plant Sciences; Plants, Genetically Modified - genetics; Promoter Regions, Genetic - genetics; Secologanin Tryptamine Alkaloids - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Transcriptional Activation; Zoology; Transcription factors; Terpenoid indole alkaloid; Madagascar periwinkle; Plant secondary metabolism
• ISSN: 0033-183X; 1615-6102
• DOI: 10.1007/s00709-015-0881-7

Catharanthus roseus
produces many pharmaceutically important terpenoid indole alkaloids (TIAs) such as vinblastine, vincristine, ajmalicine, and serpentine. Past metabolic engineering efforts have pointed to the tight regulation of the TIA pathway and to multiple rate-limiting reactions. Transcriptional regulator ORCA3 (octadecanoid responsive
Catharanthus
AP2-domain protein), activated by jasmonic acid, plays a central role in regulating the TIA pathway. In this study, overexpressing
ORCA3
under the control of a glucocorticoid-inducible promoter in
C. roseus
hairy roots resulted in no change in the total amount of TIAs measured. RT-qPCR results showed that
ORCA3
overexpression triggered the upregulation of transcripts of most of the known TIA pathway genes. One notable exception was the decrease in strictosidine glucosidase (
SGD
) transcripts. These results corresponded to previously published results. In this study,
ORCA3
and
SGD
were both engineered in hairy roots under the control of a glucocorticoid-inducible promoter. Co-overexpression of
ORCA3
and
SGD
resulted in a significant (
p
 < 0.05) increase in serpentine by 44 %, ajmalicine by 32 %, catharanthine by 38 %, tabersonine by 40 %, lochnericine by 60 % and hörhammericine by 56 % . The total alkaloid pool was increased significantly by 47 %. Thus, combining overexpression of a positive regulator and a pathway gene which is not controlled by this regulator provided a way to enhance alkaloid production.