Abstract
The OsTHION family represents a class of cysteine-rich signal peptides widely recognized for their significant roles in plant disease resistance and immunity. While members of this family are known to be induced under various biotic and abiotic stresses, their responses to environmental stressors beyond disease resistance remain underexplored. This study investigates the evolution, expression patterns, and functional roles of the OsTHION gene family in rice (Oryza sativa) under diverse stress conditions. Using sequence data from the Phytozome database, we identified 44 OsTHION family members and classified them into four groups based on phylogenetic analysis. Cis-acting element analysis revealed that the promoter regions of OsTHION genes are enriched with regulatory elements associated with light response, hormone signaling, plant growth, and stress responses. The OsTHION genes exhibit complex organ-specific expression patterns, with OsTHION30 and OsTHION36 showing ubiquitous expression, while other members are highly expressed in specific tissues or developmental stages. Under drought, salt, and low-temperature stress, OsTHION genes undergo significant expression changes, underscoring their critical role in plant adaptation to environmental challenges. Notably, OsTHION15 was markedly upregulated under drought stress, and the Osthion15 mutant displayed heightened sensitivity to drought and ABA stress, confirming its pivotal role in stress resistance. RNA sequencing analysis identified many differentially expressed genes (DEGs), primarily enriched in pathways related to ribosomal function and plant hormone signaling, suggesting that OsTHION15 may regulate stress responses through multiple mechanisms. In summary, this study advances our understanding of the OsTHION gene family and highlights its intricate involvement in regulating rice growth, development, and environmental stress responses. These findings offer valuable insights and technical support for crop improvement, with potential applications in enhancing environmental adaptability and yield stability in crops.