Submitted to: Biochemistry and Biophysics Research Communication
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2018
Publication Date: 2/6/2018
Citation: Knollenberg, B.J., Liu, J., Yu, S., Lin, H., Tian, L. 2018. Functional characterization of a p-coumaroyl quinate/shikimate 3’-hydroxylase from potato (Solanum tuberosum). Biochemistry and Biophysics Research Communication. 496:462-467. Interpretive Summary: Plants produce an array of secondary metabolic compounds which function as a defense in response to biotic and abiotic stress. Chlorogenic acid (CGA) is a secondary metabolite that plays an important role in protecting plants against pathogens. In this study, a molecular approach was used to functionally characterize a key enzyme, C3’H (p-coumaroyl quinate/shikimate 3’-hydroxylase) that synthesizes CGA in potato. Study results indicate that while biosynthesis of CGA in potato tubers is controlled by C3’H, other metabolic process also could be involved in regulation of CGA biosynthesis in potato. Information derived from this study provides new insights into plant defense response to stress.
Technical Abstract: Chlorogenic acid (CGA) plays an important role in protecting plants against pathogens and promoting human health. Although CGA accumulates to high levels in potato tubers, the key enzyme p-coumaroyl quinate/shikimate 3’-hydroxylase (C3’H) for CGA biosynthesis has not been isolated or characterized in potato. In this work, cloned StC3’H from potato catalyzed formation of caffeoylshikimate and CGA (caffeoylquinate) from p-coumaroyl shikimate and p-coumaroyl quinate, respectively, but was inactive towards p-coumaric acid in enzyme assays conducted in vitro. When expression of StC3’H proteins was blocked through antisense (AS) inhibition under the control of a tuber-specific patatin promoter, moderate changes in tuber yield as well as phenolic metabolites in core tuber tissues were observed for several AS lines. However, as AS and control lines exhibited similar responses to the bacterial pathogen, Pectobacterium carotovorum, a direct role for StC3’H in defense of potato was not demonstrated.