New insights into ethylene-induced latex flow in a dose-dependent manner in rubber tree

Ethylene enhances latex flow and latex regeneration in rubber trees. The physiological regulation of ethylene-stimulated latex flow mainly involves processes such as alleviating laticifer plugging, prolonging latex flow duration, increasing laticifer turgor pressure, and enhancing latex stability. The molecular mechanisms underlying these physiological effects, particularly those related to the ethylene signaling transduction pathway, remain unclear. This study aims to establish the link between these physiological changes and specific genes in the ethylene signaling pathway. We identified four ethylene dose-dependent response factors, namely HbRAP2.3, HbERF110, HbERF3, and HbERF1B, and a cluster of ethylene dose-dependent genes, including those encoding enzymes involved in latex stability, such as HbPMCA4 and HbGCL, and those involved in latex coagulation, such as HbGLU14 and HbECH. These genes exhibit a similar expression pattern with these ethylene dose-dependent response factors, and the promoter region of some contains the "GCC-box", the core sequence for ERFs binding. This suggests that they may be directly regulated by these ethylene dose-dependent response factors. Additionally, we cloned HbRAP2.3, which can activate the expression of latex flow-related genes HbGLU14 and HbECH. These findings provide novel insights into the intricate relationship between ethylene signaling and latex flow in rubber trees, laying the foundation for future research aimed at optimizing latex yield.