What is the role of monobutyl phthalate (MBP) in activating the jasmonic acid signaling pathway in rice?

Monobutyl phthalate (MBP) is a hydrolyzed product of dibutyl phthalate (DBP), a common phthalate ester (PAE) found in agricultural soils. The study investigates whether MBP can mimic jasmonic acid (JA) to activate the JA signaling pathway in rice, which is crucial for pest defense but can inhibit plant growth.

From: "Transformation metabolites of phthalate esters (PAEs) inhibited rice growth through jasmonic acid signaling pathway", Environment International, Volume 201, July 2025, 109553

The study discovered that MBP can activate the JA signaling pathway in rice. MBP conjugated with isoleucine to form MBP-Ile, which mimicked the JA bioactivator (JA-isoleucine conjugate) and occupied the binding site of the COI1-JAZ co-receptor protein, initiating the JA signaling pathway. This activation led to upregulated genes encoding COI1, JAZ, and MYC2, and increased production of phytoalexins. The study concludes that MBP, as a JA structural analogue, can trigger the JA signaling pathway, enhancing pest defense but inhibiting rice growth.