Insight into the mechanisms of enhanced production of valuable terpenoids by arbuscular mycorrhiza

Terpenoids, in addition to being essential for plant growth and survival, are commercially valued for their medicinal properties, ecological significance, and used as flavors and fragrances. Prospective role of arbuscular mycorrhiza (AM) symbiosis in improving the accumulation of secondary metabolites especially terpenoids has gained recognition over the past two decades. Increased production of terpenoids in aboveground parts of AM-colonized medicinal plants has extensively been described. Understanding the mechanisms underpinning increase in accumulation of specific terpenoids in AM plants is important for obtaining higher yield and to improve the potential of AM in sustainable cultivation of plants harboring these compounds. Enhanced phosphorus uptake in the mycorrhizal plants has been largely credited for the increase in terpenoid production. However, recent findings have suggested AM mediated manipulation of morphology, biochemistry and gene transcription in plants. The review provides an update on recent findings in the field of AM research with a special focus on production of pharmaceutically important terpenoids. Several points are highlighted for future research to elucidate probable mechanisms underlying increase in terpenoids in mycorrhizal plants.