Biology Department Seminar

Medicago truncatula, a close relative of alfalfa but with a relatively small diploid genome, has been chosen as a model legume. It is a rich source of natural products, such as flavonoids, isoflavonoids and triterpenes, which impact its properties as a forage legume. Isoflavonoids are a predominantly legume-specific subclass of flavonoid secondary metabolites, with roles in plant defence and nodulation. They also exhibit a wide range of beneficial effects on human health, including estrogenic and anti-cancer activity. Triterpenoid saponins are naturally occurring sugar conjugates of triterpenes possessing various biological activities, including anti-microbial, anti-insect, and allelopathic. Saponins also exhibit anticholesterolemic, anti-cancer and hemolytic activities, and are important components of a number of herbal medicines. Root-derived cell suspension cultures of Medicago truncatula accumulate the isoflavonoid-derived pterocarpan phytoalexin medicarpin in response to treatment with yeast elicitor, and more than 30 triterpene saponins after exposure to the wound signal methyl jasmonate. An integrated transcriptome/metabolome analysis has been applied to understand the molecular basis of this elicitor-mediated genetic reprogramming. This approach has revealed different molecular mechanisms underlying the metabolic responses to pathogen and wound signals in the Medicago cell suspension cultures, as well as the identification of novel genes involved in the biosynthesis and regulation of the induced natural products.