RESUMO
In 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 × 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 ß-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.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Transferases Intramoleculares/genética , Medicago/metabolismo , Sapogeninas/metabolismo , Saponinas/metabolismo , Sequência de Bases , Sistema Enzimático do Citocromo P-450/metabolismo , Regulação da Expressão Gênica de Plantas , Transferases Intramoleculares/metabolismo , Medicago/genética , Medicago sativa/genética , Medicago sativa/metabolismo , Medicago truncatula/genética , Medicago truncatula/metabolismo , Dados de Sequência Molecular , Especificidade de Órgãos , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Análise de Sequência de DNA , Triterpenos/metabolismoRESUMO
Nowadays, feed and food safety and traceability are of primary importance. Hence, a correct labeling of the different products is highly desirable in general, but mandatory for those people who are suffering from eating disorders and food allergies. Among the technologies that have been developed for feed and food analysis, the patented tubulin-based polymorphism (TBP) method emerges as an easy, versatile, and inexpensive diagnostic tool. Initially used to fingerprint different plant species and varieties, TBP was then successfully applied to trace species in mixtures of plant origin such as commercial feeds. TBP is a DNA-based molecular marker, that makes use of PCR for the selective amplification of plant ß-tubulin introns. Amplified fragments are then separated by PAGE and visualized by silver staining. We have now developed an improved version of TBP. Based on capillary electrophoresis and fluorescence detection, it makes the method automatic, more sensible, reproducible, and faster. Compared to the classic TBP, this new version allows to obtain a better data resolution and an easier interpretation of the results, clearing the way to large-scale feed/food diagnostics.
