Sapogenin content variation in Medicago inter‐specific hybrid derivatives highlights some aspects of saponin synthesis and control

Abstract

SummaryIn the Medicago genus, saponins are a complex mixture of triterpene glycosides showing a broad spectrum of biological properties. Here we analyzed the variation in the sapogenin content and composition of inter-specific hybrid Medicago sativa 9 Medicago arborea derivatives to highlight the pattern of this variation in plant organs (leaves/roots) and the possible mechanisms underlying it.In Sativa Arborea Cross (SAC) leaves and roots, saponins and sapogenins were evaluated using chromatographic methods. Phenotypic correlations between sapogenin content and bio-agronomic traits were examined. Expression studies on b-amyrin synthase and four cytochromes P450 (CYPs) involved in sapogenin biosynthesis and sequence analysis of the key gene of the hemolytic sapogenin pathway (CYP716A12) were performed.Chromatographic analyses revealed a different pattern of among-family variation for hemolytic and nonhemolytic sapogenins and saponins and for the two organs/tissues. Different correlation patterns of gene expression in roots and leaves were found. Diachronic analysis revealed a relationship between sapogenin content and gene transcriptional levels in the early stages of the productive cycle.The results suggest that there are different control mechanisms acting on sapogenin biosynthesis for leaves and roots, which are discussed. A key role for medicagenic acid in the control of sapogenin content in both the tissues is proposed and discussed.

Distribution of sapogenins in morphological Medicago sativa L. parts: Comparison of various extraction techniques

“…The main sapogenin was medicagenic acid. Similar results for Medicago sativa were obtained in the studies by Carelli et al [29]. Medicagenic acid was a major saponin glycosyde in roots and leaves.…”

“…Hydrolysis of saponins was carried out with 2 M hydrochloric acid under reflux for 8 h. Other identified sapogenins were zanhic acid and soyasapogenol A. Similar results for Medicago sativa were obtained in the studies by Carelli et al [29]. In this study, sapogenins were obtained by acid hydrolysis and quantified by GC-FID.…”

Activity of Saponins from Medicago Species against Phytoparasitic Nematodes

“…The high molecular weight compounds detected at higher amounts in M. hybrida, M. lupulina and M. truncatula extracts, in particular saponins containing glycosides of medicagenic and zanhic acids, were previously identified in the aerial parts of Medicago species [8], including M. arborea [28], M. sativa [31], M. truncatula [37] and M. marina [32]. Given that zanhic acid is synthesized in the green parts of the plants [39], its glycosides have not previously been found in M. lupulina and M. hybrida [8,38] when roots were investigated.…”

CYP72A67 Catalyzes a Key Oxidative Step in Medicago truncatula Hemolytic Saponin Biosynthesis

“…Besides, it was differentially expressed in genome-wide transcript profiling of the Medicago truncatula lha-1 mutant lacking hemolytic saponins (Carelli et al, 2011) and consistently coexpressed with CYP716A12 and CYP72A68 (Fukushima et al, 2013), both involved in hemolytic sapogenin biosynthesis, in hybrid derivatives between M. sativa and M. arborea (Carelli et al, 2015).…”