Molecular characterization of three 3-hydroxy-3-methylglutaryl-CoA reductase genes including pathogen-induced Hmg2 from pepper ( Capsicum annuum)

• Published in: Biochimica et biophysica acta 2003-02, Vol.1625 (3), p.253-260
• Main Authors: Ha, Sun-Hwa, Kim, Jong-Bum, Hwang, Young-Soo, Lee, Shin-Woo
• Format: Article
• Language: English
• Subjects: 3-Hydroxy-3-methylglutaryl-CoA reductase; Alkyl and Aryl Transferases - biosynthesis; Alkyl and Aryl Transferases - genetics; Amino Acid Sequence; Capsicum - enzymology; Capsicum - genetics; Capsicum - metabolism; Capsicum - parasitology; Cloning, Molecular; Gene Expression Regulation, Enzymologic; Gene Library; Geranyltranstransferase; HMGB2 Protein - biosynthesis; HMGB2 Protein - genetics; Hydroxymethylglutaryl CoA Reductases - biosynthesis; Hydroxymethylglutaryl CoA Reductases - genetics; Hydroxymethylglutaryl-CoA-Reductases, NADP-dependent - biosynthesis; Hydroxymethylglutaryl-CoA-Reductases, NADP-dependent - genetics; Isoenzymes - genetics; Isoprenoids biosynthetic pathway; Molecular Sequence Data; Pepper ( Capsicum annuum L.); Phytophthora - pathogenicity; Phytosterols - biosynthesis; RNA, Messenger - analysis; Sequence Alignment; Sesquiterpene phytoalexin; Sesquiterpenes - metabolism
• ISSN: 0167-4781; 0006-3002; 1879-2634
• DOI: 10.1016/S0167-4781(02)00624-3

Sesquiterpene phytoalexins, a class of plant defense metabolites, are synthesized from the cytosolic acetate/mevalonate pathway in isoprenoids biosynthetic system of plants. The 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) catalyzes the synthesis of mevalonate, which is the specific precursor of this pathway, as a multi gene family. Three kinds of cDNA clones encoding HMGR were isolated from Korean red pepper ( Capsicum annuum L. cv. NocKwang) and the HMGR2 gene ( Hmg2) was especially obtained from a cDNA library constructed with Phytophthora capsici-infected pepper root RNAs. The Hmg2 encoding a 604-amino-acid peptide had typical features as an elicitor-induced isoform among HMGRs on its gene structure and had a predicted amino acid sequence homology. In addition, the expression of Hmg2 was rapidly induced within 1 h in response to a fungal pathogen and continuously increased up to 48 h . Together with sesquiterpene cyclase gene that was strongly induced 24 h after pathogen-infection, the Hmg2 and farnesyl pyrophosphate synthase gene were coordinately and sequentially regulated for the biosynthesis of defense-related sesquiterpene phytoalexins in pepper.