A metabolic gene cluster in Lotus japonicus discloses novel enzyme functions and products in triterpene biosynthesis. Issue 3 (26th July 2013)

• Record Type: Journal Article
• Authors: Krokida, Afrodite; Delis, Costas; Geisler, Katrin; Garagounis, Constantine; Tsikou, Daniela; Peña‐Rodríguez, Luis M.; Katsarou, Dimitra; Field, Ben; Osbourn, Anne E.; Papadopoulou, Kalliope K.
• Is Part Of: New phytologist. Volume 200:Issue 3(2013)
• Page Start: 675
• Page End: 690
• Publication Date: 2013-07-26
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/nph.12414
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" id="nph12414-abs-0001"> <title>Summary</title> <p> <list id="nph12414-list-0001" list-type="bullet"> <list-item> <p>Genes for triterpene biosynthetic pathways exist as metabolic gene clusters in oat and <italic>Arabidopsis thaliana</italic> plants. We characterized the presence of an analogous gene cluster in the model legume <italic>Lotus japonicus</italic>.</p> </list-item> <list-item> <p>In the genomic regions flanking the oxidosqualene cyclase <italic>AMY2</italic> gene, genes for two different classes of cytochrome P450 and a gene predicted to encode a reductase were identified. Functional characterization of the cluster genes was pursued by heterologous expression in <italic>Nicotiana benthamiana</italic>. The gene expression pattern was studied under different developmental and environmental conditions. The physiological role of the gene cluster in nodulation and plant development was studied in knockdown experiments.</p> </list-item> <list-item> <p>A novel triterpene structure, dihydrolupeol, was produced by AMY2. A new plant cytochrome P450, CYP71D353, which catalyses the formation of 20‐hydroxybetulinic acid in a sequential three‐step oxidation of 20‐hydroxylupeol was characterized. The genes within the cluster are highly co‐expressed during root and nodule development, in hormone‐treated plants and under various environmental stresses. A transcriptional gene silencing mechanism that appears to be involved in the regulation of the cluster genes was also revealed.</p> </list-item> <list-item> <p>A tightly co‐regulated cluster of functionally related genes is involved in legume triterpene biosynthesis, with a possible role in plant development.</p> </list-item> </list> </p> </abstract>