Structural and transcriptional characterization of Thaumatin-Like Proteins in Cenostigma pyramidale under salt stress

Thaumatin-Like Proteins (TLPs) play a crucial role against biotic and abiotic stresses, acting as signaling molecules in transduction pathways and exhibiting antimicrobial activity. The present study aimed to characterize TLPs of Cenostigma pyramidale (Fabaceae) and analyze their expression (RNA-Seq) in root tissues under salt stress. A total of 36 CpTLPs were identified, which showed the characteristic TLP domain and a signal peptide in the N-terminal region. Multiple sequence alignment revealed the conservation of 16 cysteine residues, a signature motif, and a "REDDD" motif, all characteristic of TLPs. Three typical TLPs domains were identified in the three-dimensional modeling of the six analyzed sequences. The molecular dynamics simulation revealed stability along most of these sequences. RNA-seq under salt stress showed that six C. pyramidale TLPs (CpTLP2, CpTLP3, CpTLP5, CpTLP17, CpTLP20, and CpTLP31) were differentially expressed. The RT-qPCR expression validation was performed in leaf and root tissues (30 min, 2 h, and 11 days after salt stress). In leaf tissue, most CpTLPs were induced in at least one time point analyzed. In root tissue, we observed validation of the RNA-Seq expression data of CpTLP3, CpTLP5, CpTLP20, and CpTLP31, as well as distinct expression patterns between leaf and root tissues. Our results showed significant variations in the transcriptional response of the TLP family across different plant tissues and associated specific genes of this family with salt tolerance in C. pyramidale. These findings enhance the understanding of the role of TLPs in salt stress and may be useful in genetic improvement strategies to increase salt tolerance.