Plant terpenoids and their precursors, terpenes, are among the most
important classes of plant secondary metabolites that have provoked increased interest
regarding their application in the medical field to treat different health issues.
Additionally, terpenoids are known to play a crucial role in many different plant
processes, such as photosynthesis, root growth, flower production, fruit set, and plant
interaction with the environment. A plant can produce different kinds of terpenoids
with diverse structures and functions. These compounds are usually liberated in the
atmosphere in the form of flavors or fragrance compounds or stored in plant organs,
such as glandular trichomes. Due to increased water scarcity, salt stress, mineral
deficit, temperature level, and pathogens resistance, it has become difficult to provide
natural conditions for the development of some plant species, which has led to a
shortage in levels of some naturally occurring compounds, such as terpenoids. So, to
reduce the alteration of terpenoid production, some strategies have been recently
applied, like metabolic engineering and applying biofertilizers. Thus, this chapter will
define the different classes of terpenoids produced by plants, their metabolic pathways,
and their roles in plant development and physiology, nodule formation, mycorrhizal
symbiosis, wounding healing, and plant defense as well as recent advances regarding
the increase in the accumulation of terpenoids through metabolic engineering and
exogenous application of natural substances.
Keywords: Mycorrhiza, Metabolic engineering, Nodulation, Plant growth, Phytohormones, Terpenoids.
