Rapid ethylene-triggered protein complex remodeling in dark-grown Arabidopsis hypocotyls

Protein-level cellular dynamics, including multimerization, play a crucial role in the rapid adaptation of plants during developmental transitions and environmental stresses. The gaseous phytohormone ethylene is a key regulator of rapid cellular growth. During soil emergence, etiolated seedlings undergo crucial morphological changes to their apical hooks and hypocotyls, with ethylene inhibiting hypocotyl axial elongation while promoting radial expansion. Ethylene triggers these growth responses within 2 h; however, the protein machinery and cellular processes that control morphogenesis in Arabidopsis (Arabidopsis thaliana) are unknown. Here, we used quantitative proteomics and co-fractionation mass spectrometry to test for rapid ethylene-dependent changes in protein abundance and protein complex composition. Protein multimerization responses were numerous and diverse. There were instances of protein complex assembly and disassembly, with varying degrees of completeness. Small-scale validation tests indicated that the identified proteins play a role in hypocotyl development and suggested that this approach to gene discovery can identify potential targets for ethylene-mediated growth regulation and enhanced seedling adaptability during early development.