Impact of AM Symbiosis on Apocarotenoid Production in Plants

Arbuscular mycorrhizal (AM) fungi form a vital symbiotic relationship with plants, enhancing nutrient acquisition and stress resilience. A particularly intriguing aspect of this symbiosis is its influence on plant secondary metabolism, specifically the production of apocarotenoids. These bioactive compounds, derived from carotenoids, play a crucial role in plant development, signaling, and stress responses. This chapter delves into the reciprocal interaction between AM fungi and the biosynthesis of apocarotenoids, focusing on how these fungi regulate carotenoid metabolism to improve plant fitness under environmental stress. The presence of AM fungi enhances the synthesis of key enzymes involved in carotenoid biosynthesis, such as phytoene synthase (PSY) and carotenoid cleavage dioxygenases (CCDs), which are responsible for the production of strigolactones (SLs) and abscisic acid (ABA). These compounds, in turn, promote fungal colonization, enhance stress tolerance, and optimize resource acquisition, particularly under nutrient-limited conditions. Additionally, the chapter explores the signaling networks and hormonal crosstalk between AM fungi and plants that fine-tune apocarotenoid production. The ecological and agricultural implications of AM-induced apocarotenoids are discussed, highlighting their potential to improve plant resilience and sustainability in agricultural systems. This mutualistic interaction offers valuable insights into optimizing plant health and productivity in the face of climate change.