A Seed-Specific Regulator of Triterpene Saponin Biosynthesis in Medicago truncatula

Author(s):Show less -

Ribeiro, Bianca ^{[1, 2]} ; Lacchini, Elia ^{[1, 2]} ; Bicalho, Keylla U. ^{[3, 1, 2]} ; Mertens, Jan ^{[1, 2]} ; Arendt, Philipp ^{[1, 2]} ; Vanden Bossche, Robin ^{[1, 2]} ; Calegario, Gabriela ^{[1, 2]} ; Gryffroy, Lore ^{[1, 2]} ; Ceulemans, Evi ^{[1, 2]} ; Buitink, Julia ^[4] ; Goossens, Alain ^{[1, 2]} ; Pollier, Jacob ^{[1, 2, 5]}

Affiliation

^[1] Univ Ghent, Dept Plant Biotechnol & Bioinformat, B-9052 Ghent - Belgium

^[2] VIB Ctr Plant Syst Biol, B-9052 Ghent - Belgium

^[3] Sao Paulo State Univ UNESP, Inst Chem, Dept Organ Chem, BR-14800900 Araraquara, SP - Brazil

^[4] Univ Angers, Inst Rech Hort & Semences, Unites Mixtes Rech, INRAE, Inst Agro, SFR 4207, QuaSaV, F-49071 Beaucouze - France

^[5] VIB Metab Core, B-9052 Ghent - Belgium

• Document type: Journal article
• Source: PLANT CELL; v. 32, n. 6, p. 2020-2042, JUN 2020.
• Web of Science Citations: 0

Abstract

The discovery of a seed-specific regulator of hemolytic saponin biosynthesis in Medicago truncatula led to the identification of the missing P450 in the biosynthetic branch of these plant defense compounds. Plants produce a vast array of defense compounds to protect themselves from pathogen attack or herbivore predation. Saponins are a specific class of defense compounds comprising bioactive glycosides with a steroidal or triterpenoid aglycone backbone. The model legume Medicago truncatula synthesizes two types of saponins, hemolytic saponins and nonhemolytic soyasaponins, which accumulate as specific blends in different plant organs. Here, we report the identification of the seed-specific transcription factor TRITERPENE SAPONIN ACTIVATION REGULATOR3 (TSAR3), which controls hemolytic saponin biosynthesis in developing M. truncatula seeds. Analysis of genes that are coexpressed with TSAR3 in transcriptome data sets from developing M. truncatula seeds led to the identification of CYP88A13, a cytochrome P450 that catalyzes the C-16 alpha hydroxylation of medicagenic acid toward zanhic acid, the final oxidation step of the hemolytic saponin biosynthesis branch in M. truncatula. In addition, two uridine diphosphate glycosyltransferases, UGT73F18 and UGT73F19, which glucosylate hemolytic sapogenins at the C-3 position, were identified. The genes encoding the identified biosynthetic enzymes are present in clusters of duplicated genes in the M. truncatula genome. This appears to be a common theme among saponin biosynthesis genes, especially glycosyltransferases, and may be the driving force of the metabolic evolution of saponins. (AU)

• FAPESP's process: 17/10911-1 - Combinatorial biosynthesis of triterpenes in Saccharomyces cerevisiae and Nicotiana benthamiana systems using P450 enzymes on friedelin substrate
• Grantee: Keylla Utherdyany Bicalho
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor