Warm temperatures regulate andrographolide biosynthesis through jasmonic acid signaling mediated by the <scp>ApMYC2</scp> – <scp>ApHSFB2b</scp> module in <i>Andrographis paniculata</i>

Andrographis paniculata (Acanthaceae) produces andrographolide (AD), a diterpene compound with anti-inflammatory and antimicrobial activities. A. paniculata primarily occurs in tropical and subtropical regions characterized by high temperatures. However, the effects of temperature on A. paniculata development and metabolism, and the underlying regulatory mechanisms remain poorly understood. In this study, we demonstrate that warm temperature promotes plant growth and AD accumulation in A. paniculata. Metabolomic and transcriptomic analyses revealed that the transcription factors ApMYC2 and ApHSFB2b are strongly associated with AD production, and these transcription factors form a complex to regulate gene expression. Warm temperatures enhance jasmonic acid (JA) accumulation, which activates expression of the copalyl-diphosphate synthase gene ApCPS1, encoding a key enzyme in AD biosynthesis, through the ApMYC2-ApHSFB2b regulatory module. Furthermore, the jasmonate ZIM domain (JAZ) JA signaling repressors ApJAZ1 and ApJAZ9 interact with ApMYC2, thereby inhibiting activation of ApCPS1 mediated by ApMYC2 and ApHSFB2b. Our findings elucidate a temperature-dependent mechanism regulating AD biosynthesis in A. paniculata, mediated by JA signaling through the ApMYC2-ApHSFB2b module, providing critical insights into how temperature regulates terpenoid metabolism in plants.