Identification and Functional Characterization of Salt-Tolerant Long Non-Coding RNAs in Tamarix hispida

Long non-coding RNAs (lncRNAs) play an important role in plant growth and development, and they also respond to various abiotic stresses by participating in transcriptional, post-transcriptional, and epigenetic regulation. In this study, we identified salt-responsive lncRNAs in the roots and leaves of Tamarix hispida and characterized their functions. In total, 7198 mRNAs and 1112 salt-induced lncRNAs were identified using RNA-seq. The potential target genes of these salt-responsive lncRNAs were enriched in "metabolic process," "cellular process," "single-organism process," and "response to stimulus" in both roots and leaves. We identified and characterized five lncRNAs associated with salt tolerance in T. hispida (designated ThSAIR1-ThSAIR5). The expression of these lncRNAs was induced by salt stress. ThSAIR1-ThSAIR5 overexpression vectors were constructed, and overexpression plants were generated using Agrobacterium-mediated efficient transient transformation technology. The impact of elevated gene function on salt stress tolerance was then studied. The transient overexpression of ThSAIR1-ThSAIR5 enhances reactive oxygen species (ROS) scavenging capability and proline biosynthesis in T. hispida under salt stress. Additionally, the target gene of ThSAIR5, ThNAC86, was further identified through transcriptome sequencing and subsequently transformed into Arabidopsis thaliana, resulting in improved salt tolerance in the transgenic plants. These results demonstrated that ThSAIR5 positively regulates salt tolerance by modulating the expression of ThNAC86, suggesting that it may serve as a candidate gene for molecular breeding aimed at developing plants with enhanced salt tolerance.