Identification and Expression Analysis of R2R3-MYB Family Genes Associated with Salt Tolerance in Cyclocarya paliurus

R2R3-MYB transcription factors are most abundant in the MYB superfamily, while the R2R3-MYB genes play an important role in plant growth and development, especially in response to environmental stress. Cyclocarya paliurus is a multifunction tree species, and the existing resources cannot meet the requirement for its leaf production and medical use. Therefore, lands with some environmental stresses would be potential sites for developing C. paliurus plantations. However, the function of R2R3-MYB genes in C. paliurus in response to environmental stress remains unknown. In this study, to identify the roles of R2R3-MYB genes associated with salt stress response, 153 CpaMYB genes and their corresponding protein sequences were identified from the full-length transcriptome. Based on the comparison with MYB protein sequences of Arabidopsis thaliana, 69 R2R3-MYB proteins in C. paliurus were extracted for further screening combined with conserved functional domains. Furthermore, the MYB family members were analyzed from the aspects of protein sequences alignment, evolution, motif prediction, promoter cis-acting element analysis, and gene differential expression under different salt treatments using both a pot experiment and hydroponic experiment. The results showed that the R2R3-MYB genes of C. paliurus conserved functional domains, whereas four R2R3-MYB genes that might respond to salt stress via regulating plant hormone signals were identified in this study. This work provides a basis for further functional characterization of R2R3-MYB TFs in C. paliurus.

Automated summary

R2R3-MYB genes play an important role in plant growth and response to environmental stress. This study identified and analyzed the function of R2R3-MYB genes in Cyclocarya paliurus in response to salt stress. The results showed that the R2R3-MYB genes of C. paliurus have conserved functional domains, and four genes that might be involved in salt stress response were identified.