Roles of the SPL gene family and miR156 in the salt stress responses of tamarisk (Tamarix chinensis)

Background: Accumulating evidences show that SPLs are crucial regulators of plant abiotic stress tolerance and the highly conserved module miR156/SPL appears to balance plant growth and stress responses. The halophyte Tamarix chinensis is highly resistant to salt tress. SPLs of T. chinensis (TcSPLs) and theirs roles in salt stress responses remain elusive. Results: In this study, we conducted a systematic analysis of the TcSPLs gene family including 12 members belonging to 7 groups. The physicochemical properties and conserved motifs showed divergence among groups and similarity in each group. The microRNA response elements (MREs) are conserved in location and sequence, with the exception of first MRE within TcSPL5. The miR156-targeted SPLs are identified by dual-luciferase reporter assay of MRE-miR156 interaction. The digital expression gene profiles cluster suggested potential different functions of miR156-targeted SPLs vs non-targeted SPLs in response to salt stress. The expression patterns analysis of miR156-targeted SPLs with a reverse expression trend to TcmiR156 suggested 1 h (salt stress time) could be a critical time point of post-transcription regulation in salt stress responses. Conclusions: Our work demonstrated the post-transcription regulation of miR156-targeted TcSPLs and transcription regulation of non-targeted TcSPLs in salt stress responses, and would be helpful to expound the miR156/SPL-mediated molecular mechanisms underlying T. chinensis salt stress tolerance.