Meeting the challenge of stevioside production in the hairy roots of Stevia rebaudiana by probing the underlying process

摘要

Agrobacterium rhizogenes mediated "hairy root cultures" of the renowned bio-sweetener producing plant-Stevia rebaudiana, were generated to explore their yet undetected biosynthetic potentials concerning the low calorie diterpene glycoside-stevioside. Four stable rhizoclones were studied under light and dark conditions showing better growth under dark. Two of these rhizoclones revealed substantially higher photosynthetic pigment accumulation under light. Evidently, capitalization on the available inter-clonal variability first time showed the stevioside synthesizing exclusivity in the SRA4 rhizoclone under light condition, while the rest failed. The dualities of the glycoside synthesizing power amongst the two photosynthetically active rhizoclones were resolved through quantitative RT-PCR analysis of UGT85C2 gene showing positive expression in the stevioside producing rhizoclone. These findings elucidated the decisive role of UGT85C2 in combination with photosynthetic proficiency of the studied hairy root cultures in regulating the biosynthetic pathway of S. rebaudiana.