From dormancy to germination: Transcriptome analysis reveals the potential involvement of heat shock proteins in gibberellin-induced seed dormancy release in Solanum torvum.

Abstract

Solanum torvum, a superior vegetable grafting rootstock and medicinal Solanaceae plant, exhibits strong seed dormancy, which limits its commercial cultivation. Among various strategies explored to improve the germination rate of S. torvum, exogenous application of gibberellin (GA) has been shown to be effective. In this study, a GA concentration of 2.5 mM was established as the optimal for breaking dormancy in S. torvum seeds. Transcriptome analysis of dry, water-soaked, GA-soaked, and GA-induced germinated seeds was conducted to investigate the molecular mechanism of GA-mediated dormancy release. During the soaking period, GA application significantly induced transcriptome changes in processes including protein processing, translation, and peptide biosynthesis. Concurrently, GA treatment promoted plant hormone signal transduction, enhanced DNA-binding transcription factor activity, and activated monocarboxylic acid biosynthetic process, all of which facilitated seed water absorption. Furthermore, the differentially expressed genes (DEGs) induced by GA during soaking primarily functioned in signal transduction or activation. While most of these DEGs returned to their pre-treatment expression levels before subsequent recovery, a subset persisted until seed germination. During radicle protrusion, the persistent DEGs were associated with energy metabolism and cell structure establishment. Notably, heat shock protein (HSP) genes showed dynamic expression across all stages (soaking, germination, and radicle penetration). Furthermore, by adjusting germination conditions, temperature was confirmed to be a necessary but not sufficient condition for GA-induced S. torvum seed germination. However, functional validation (e.g., using HSP inhibitors or genetic approaches) is still required to confirm the causal role of HSPs. Collectively, these findings not only clarify the molecular basis of GA-regulated seed dormancy breaking in S. torvum but also provide practical guidance for optimizing its commercial propagation protocols.