Steviol glycoside biosynthesis

Area of Science:

• Plant biochemistry
• Metabolic engineering
• Natural products chemistry

Background:

• Steviol glycosides, natural sweeteners from *Stevia rebaudiana*, have been researched for over a century due to their intense sweetness.
• These compounds are diterpenoids with a biosynthetic pathway that intersects with gibberellic acid formation.
• High concentrations in *Stevia* leaf tissue drive interest in their production and properties.

Purpose of the Study:

• To elucidate the genes and enzymes involved in the biosynthesis of steviol glycosides.
• To understand the functional roles of enzymes within the steviol glycoside pathway.
• To investigate the initial committed step in the pathway: the synthesis of the aglycone steviol.

Main Methods:

• Genomic analysis to identify genes encoding biosynthetic enzymes.
• Plant biochemistry techniques for pathway elucidation.
• Functional characterization of identified enzymes, including glucosyltransferases.

Main Results:

• Rapid identification of genes responsible for the steviol glycoside biosynthetic pathway through the convergence of genomics and biochemistry.
• Ongoing functional characterization of the enzymes encoded by these genes.
• Identification of steviol as the first committed product, with subsequent glycosylation forming various leaf glycosides.

Conclusions:

• The biosynthesis of steviol glycosides is increasingly understood at the genetic and enzymatic level.
• Further functional studies will refine our knowledge of steviol glycoside production in *Stevia rebaudiana*.
• Elucidation of this pathway has implications for the production of natural sweeteners.