Integrated Transcriptomic Profiling Reveals Distinct and Overlapping Transcriptional Responses and Regulatory Pathways Mediated by Salicylic Acid, Jasmonic Acid, and Abscisic Acid in Lotus (Nelumbo nucifera).

Sacred lotus (Nelumbo nucifera) is an important aquatic crop whose growth and productivity are severely constrained by environmental stresses. Salicylic Acid (SA), Jasmonic Acid (JA), and Abscisic Acid (ABA) are key plant growth regulators (PGRs) involved in stress responses, but their regulatory mechanisms in lotus remain unclear. In this study, transcriptome sequencing was performed in lotus seedlings treated with exogenous SA, JA, and ABA to characterize hormone-responsive regulatory networks. SA predominantly resulted in transcriptional repression, with responsive genes mainly associated with photosynthesis and ribosome-related pathways, whereas JA and ABA showed similar regulatory patterns with enrichment of hormone signaling and Mitogen-activated protein kinase (MAPK) pathways, but distinct roles in defense regulation and stress adaptation. A total of 607 genes were identified as commonly responsive to the three PGRs and were significantly enriched in cold response, defense response, secondary metabolism, and photosynthesis-related pathways. Protein-protein interaction analysis identified two hub genes encoding light-harvesting chlorophyll a/b-binding proteins, suggesting that the photosynthesis-antenna proteins pathway may represent a convergent regulatory node in hormone-mediated stress responses. This study provides new insights into SA-, JA-, and ABA-mediated stress responses and identifies potential candidate genes for improving stress tolerance in lotus.