T-DNA Tagging: A Promising Tool for Functional Genomics in Medicinal Plants

Abstract

Nowadays, herbal medicines have been widely used in health care and disease treatment and the share of herbal medicinal products in pharmaceutical market is increasing rapidly in many countries. One of the main resources of active pharmaceutical ingredients of herbal medicines is secondary metabolites, many of which are structurally complex and difficult to synthesize chemically. Thus, increasing the yield of some secondary metabolites through bioengineering approaches is highly desired. However, it is difficult to achieve at present because the genetic background of most medicinal plants is not clear and the genes involved in the biosynthesis of secondary metabolites are largely unknown. Intensive studies on functional genomics in medicinal plants seem to be a key for solving this problem.The ever-growing research tools for plant functional genomics include large-scale sequencing of expression sequence tags (ESTs) or genomic DNA sequences, DNA chips, two-dimensional polyacrylamide gel electrophoresis (PAGE), mutagenesis-based methods, and so on [1]. EST sequencing is a rapid and relatively economic tool for transcriptome analysis. Through EST sequencing and subsequent computational analysis, some key enzyme genes involved in the biosynthesis of secondary metabolites have been identified and characterized in various medicinal plants, such as Glycyrrhiza uralensis [2