Yong Kyoung Kim

Molecular cloning and characterization of phenylalanine ammonia-lyase, cinnamate 4-hydroxylase and genes involved in flavone biosynthesis in Scutellaria baicalensis

The involvement of genes in flavones biosynthesis was investigated in different organs and suspension cells obtained from Scutellaria baicalensis. Three full-length cDNAs encoding phenylalanine ammonia-lyase isoforms (SbPAL1, SbPAL2, and SbAPL3) and one gene encoding cinnamate 4-hydroxylase (SbC4H) from S. baicalensis were isolated using rapid amplification of cDNA ends (RACE)-PCR. These cDNAs were used together with previously-isolated clones for 4-coumaroyl CoA ligase (4CL) and chalcone synthase (CHS) to show the expression level in different organs of S. baicalensis. These genes were upregulated in suspension cells of S. baicalensis with biotic/abiotic stress factors. The baicalin and baicalein contents in roots were 22 and 107 times higher than those in flowers, respectively. The treatment of suspension cells with methyl jasmonate (MeJa) enhanced the major flavones in S. baicalensis. Cumulatively, the results of this study should advance ability to biosynthesize important and useful medicinal compounds from a variety of plant species.

Production of phenolic compounds in hairy root culture of tartary buckwheat (Fagopyrum tataricum Gaertn).

Fagopyrum tataricum Gaertn (tartary buckwheat) is an excellent medicinal and nutrient-rich crop. It has a high content of rutin and other phenolic compounds. An experiment was conducted to investigate in vitro production of phenolic compounds from hairy root culture of tartary buckwheat. Hairy root growth was promoted by increasing culture time in MS medium. The highest hairy root growth reached up to 11.2 g/l dry weight at 18 d after placement. Transformation was confirmed by PCR using rol genes, rol A (304 bp), B (797 bp), C (550 bp), and D (1035 bp) genes which is transferred into hairy roots from the Ri-plasmid in Agrobacterium rhizogenes and is responsible for the induction of hairy root from plant species. Rutin, quercetin, (−) epicatechin, (−) catechin hydrate, gallic acid, ferulic acid, chlorogenic acid, and caffeic acid were identified both in hairy and wild type roots of tartary buckwheat. The main compound found in the both types of root was epicatechin followed by rutin. The concentration of phenolic compounds in the hairy roots of tartary buckwheat was several-fold higher compared with wild type roots of same species. Our results indicate that hairy root culture of F. tataricum is a valuable alternative approach for the production of phenolic compounds.

Effects of Auxins on Sorgoleone Accumulation and Genes for Sorgoleone Biosynthesis in Sorghum Roots

Sorgoleone is a major component of the hydrophobic root exudate of Sorghum bicolor and is of particular interest to plant chemical ecology as well as agriculture. Sorgoleone was evaluated in this study to observe the expression levels of genes involved in its biosynthesis in response to auxins. Sorgoleone content varied widely according to the duration of application and the concentrations of the auxins. When the application time was increased, the sorgoleone content increased accordingly for all concentrations of IBA (1, 3, and 5 mg/L) and at 1 mg/L for both IAA and NAA. In this study, five different sorgoleone biosynthetic genes were observed, namely DES2, DES3, ARS1, ARS2, and OMT3, which are upregulated in response to IAA, IBA, and NAA. Transcript accumulation was apparent for all genes, but particularly for DES2, which increased up to 475-fold and 180-fold following 72 h exposure to NAA and IBA, respectively, compared to no treatment.