Abstract
BackgroundElicitations are considered to be an important strategy towards improved in vitro production of secondary metabolites. In cell cultures, biotic and abiotic elicitors have effectively stimulated the production of plant secondary metabolites. However, molecular basis of elicitor-signaling cascades leading to increased production of secondary metabolites of plant cell is largely unknown. Exposure of Catharanthus roseus cell suspension culture to low dose of UV-B irradiation was found to increase the amount of catharanthine and transcription of genes encoding tryptophan decarboxylase (Tdc) and strictosidine synthase (Str). In the present study, the signaling pathway mediating UV-B-induced catharanthine accumulation in C. roseus suspension cultures were investigated.ResultsHere, we investigate whether cell surface receptors, medium alkalinization, Ca2+ influx, H2O2, CDPK and MAPK play required roles in UV-B signaling leading to enhanced production of catharanthine in C. roseus cell suspension cultures. C. roseus cells were pretreated with various agonists and inhibitors of known signaling components and their effects on the accumulation of Tdc and Str transcripts as well as amount of catharanthine production were investigated by various molecular biology techniques. It has been found that the catharanthine accumulation and transcription of Tdc and Str were inhibited by 3–4 fold upon pretreatment of various inhibitors like suramin, N-acetyl cysteine, inhibitors of calcium fluxes, staurosporine etc.ConclusionOur results demonstrate that cell surface receptor(s), Ca2+ influx, medium alkalinization, CDPK, H2O2 and MAPK play significant roles in UV-B signaling leading to stimulation of Tdc and Str genes and the accumulation of catharanthine in C. roseus cell suspension cultures. Based on these findings, a model for signal transduction cascade has been proposed.
Highlights
Elicitations are considered to be an important strategy towards improved in vitro production of secondary metabolites
Alkalinization of C. roseus cell-suspension medium in response to Ultraviolet B radiation. Van (UV-B) irradiation and its inhibition by suramin Medium alkalinization an early event occurring in elicitor- treated plant cell cultures, has been used as a marker of elicitor responses in studying elicitor-binding sites in plant cells [16]
To determine whether medium alkalinization is involved in UV-B signal transduction as an early event, six-day-old cells were exposed to UV-B irradiation for various time periods (2, 5, 10 or 20 min) and extracellular pH changes were measured in the cell-suspension medium for 120 min
Summary
Elicitations are considered to be an important strategy towards improved in vitro production of secondary metabolites. Biotic and abiotic elicitors have effectively stimulated the production of plant secondary metabolites. Exposure of Catharanthus roseus cell suspension culture to low dose of UV-B irradiation was found to increase the amount of catharanthine and transcription of genes encoding tryptophan decarboxylase (Tdc) and strictosidine synthase (Str). C. roseus produces terpenoid indole alkaloids (TIAs) as a part of its secondary metabolism. The anti-tumor dimeric alkaloids, which accumulate in the leaves of C. roseus, are composed of catharanthine and vindoline monomers and are exclusively found in C. roseus plants. C. roseus cell cultures have been investigated as alternative means of production of terpenoid indole alkaloids, but they failed to produce vindoline [6]. It has been considered desirable to produce the dimers by coupling catharanthine obtained from cell cultures with vindoline obtained from the cultivated plants. The production of catharanthine by C. roseus cell cultures has been one of the most extensively explored areas of plant cell culture and is still limited due to the low yield [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
