Abstract: To reveal the molecular mechanisms underlying the early growth responses of Guiminyinxiang(Pennisetum purpureum Schum. cv. Gui Min Yin) to growth regulator application, TMT-based quantitative proteomic technology was employed to systematically analyze differentially expressed proteins in the shoot apical meristem at 48 hours after treatment with exogenous gibberellin (GA₃) and paclobutrazol (PP333). The results showed that 38 differentially expressed proteins (31 up-regulated and 7 down-regulated) were identified in the gibberellin treatment group, while 156 differentially expressed proteins (121 up-regulated and 35 down-regulated) were identified in the paclobutrazol treatment group. GO enrichment analysis indicated that gibberellin-responsive proteins were primarily enriched in processes such as COP9 signalosome assembly and positive regulation of ubiquitin-protein transferase activity, whereas paclobutrazol-responsive proteins were mainly enriched in processes like hydrogen peroxide catabolic process and response to oxidative stress. COG classification revealed that gibberellin mainly affected amino acid transport and metabolism, while paclobutrazol primarily influenced posttranslational modification, protein turnover, and chaperones. KEGG pathway analysis demonstrated that gibberellin activated pathways such as taurine and hypotaurine metabolism and steroid biosynthesis, with an up-regulation of γ-glutamyltransferase. Paclobutrazol treatment significantly enriched pathways including phenylpropanoid biosynthesis and sphingolipid metabolism. The up-regulation of peroxidase and down-regulation of coniferyl-aldehyde dehydrogenase jointly promoted lignin accumulation, leading to plant dwarfing. In conclusion, the early response of Guiminyinxiang to exogenous growth regulators relied on a cross-regulatory network involving multiple genes and pathways. Gibberellin promoted growth by coordinating the ubiquitin-proteasome system with energy and membrane anabolism, whereas paclobutrazol inhibited plant growth by enhancing cell wall lignification and antioxidant defense.

Key words: Guiminyinxiang（Pennisetum purpureum Schum. cv. Gui Min Yin）, exogenous, gibberellin, paclobutrazol, early growth, proteomics