Transcriptome analysis reveals salt stress-related genes in Rhododendron simii and RsWRKY40 is referred to salt tolerance

The plants of Rhododendron genus hold significant economic and ornamental value. Investigating their response to salt stress is critical to breeding salt-tolerant cultivars, but this area has been relatively limited. This study utilized transcriptome analysis to identify salt stress-related genes in R. simii. Through DEGs, GO and KEGG enrichment, and expression pattern analysis, 18 candidates involved in intrinsic component of membrane, oxidoreductase activity, amino sugar and nucleotide sugar metabolism, and fructose and mannose metabolism, were identified. Additionally, through weighted gene co-expression network analysis (WGCNA), 10 candidates related to arginine and proline metabolism, plant hormone signal transduction, and amino sugar and nucleotide sugar metabolism were further screened out. Transcription factor (TF) analysis showed that 35 TFs responded to salt stress in R. simii. The overexpression of RsWRKY40 in Arabidopsis increased seed germination rate, root length, and seedling survival rate under salt conditions, suggesting RsWRKY40′s potential role in enhancing salt tolerance in transgenic Arabidopsis, making it a promising candidate for improving salt resistance in Rhododendron. These findings will provide valuable theoretical and genetic resources for breeding salt-tolerant Rhododendron cultivars.