Enhanced Accumulation\nof Health-Promoting Cajaninstilbene\nAcid in Pigeon Pea Hairy Root Cultures Cocultured with an Endophytic\nFungus during Early Stages of Colonization

Endophytic fungi can effectively regulate the biosynthesis\nof health-beneficial\nmetabolites in plants. However, few studies have revealed how the\naccumulation of host metabolites varies during interactions with endophytic\nfungi. Here, pigeon pea hairy root cultures (PPHRCs) were cocultured\nwith an endophytic fungus Penicillium rubens to explore the impact on the biosynthesis and accumulation of cajaninstilbene\nacid (CSA). The results showed that CSA accumulation in PPHRCs increased\nsignificantly (15.29-fold) during the early stages of P. rubens colonization (fungal attachment and invasion\nphases). Once P. rubens successfully\ncolonized the intercellular gap of hairy roots to form a symbiotic\nrelationship, the CSA levels in PPHRCs decreased drastically. Moreover, P. rubens could be recognized by plant pattern recognition\nreceptors that regulate immunity/symbiosis, triggering the expression\nof genes related to pathogenesis, CSA biosynthesis, and ABC transporter.\nOverall, P. rubens could enhance the\naccumulation of health-promoting CSA in PPHRCs during the early stages\nof colonization.