rising stars：環境への適応：ホルモンシグナル伝達から遺伝子サイレンシングまで

The survival of plants depends on sensitive and efficient systems that perceive and integrate internal hormonal signals with external environmental cues. Deciphering how plants sense and adapt to changing conditions is a fundamental biological question with direct relevance to crop improvement and sustainable agriculture. Hongwei Guo received training in plant molecular genetics and light signaling during his doctoral studies, then turned to how diverse signal pathways converge to coordinate plant development. In his postdoctoral work, he identified EBF1/2-mediated ubiquitin-proteasome turnover of EIN3 as a core mechanism of ethylene signaling. Building on this foundation, his independent research uncovered additional post-transcriptional strategies: proteolytic cleavage and translational repression that fine-tune ethylene responses. He also established an EIN3-centered regulatory network that integrates hormonal and environmental cues to coordinate diverse physiological processes. A forward genetic screen of ethylene-activated plants unexpectedly extended Dr. Guo's research to siRNA-based regulation. His group discovered a cytoplasmic "dual-safeguard" mechanism in which impairment of mRNA decay triggers the production of coding-transcript-derived siRNAs (ct-siRNAs) that silence endogenous genes. They further showed that stress-induced 22-nt ct-siRNAs amplify silencing to modulate nitrate assimilation and energy balance under abiotic stress. More recently, Dr. Guo's laboratory has focused on how plant cells sense physical and chemical changes in their surroundings. They identified two extracellular peptide-receptor complexes as apoplastic pH sensors, and demonstrated that cytoplasmic protein DCP5 senses osmotic stress through phase separation to form new stress granules and rapidly reprogram gene expression. Collectively, Dr. Guo's research connects hormone signaling, gene regulation, and environmental adaptation.