Transcriptome Identification of R2R3-MYB Gene Family Members in Pinus massoniana and PmMYB4 Response to Drought Stress

Abstract

One of the largest families of transcription factors in plants, the MYB transcription factors family (Myeloblastosis, MYB TF), plays a vital role in regulating plant biochemical and physiological processes. The role of MYB TF in coping with stresses, such as drought, salt and cold, has been reported. Unfortunately, a comprehensive identification of R2R3-MYB TF in Masson pine (Pinus massoniana) has not been achieved. In this study, a total of 49 sequences were identified as R2R3-MYB TF. The structure, function and phylogenetic relationships of the conserved structural domains of Masson pine R2R3-MYB TF and Populus trichocarpa Torr. & A.Gray ex Hook. TFs were compared using bioinformatics tools. The results showed that Masson pine R2R3-MYB TF was divided into 24 groups, mainly located in the nucleus, and mostly lacking signal peptides and transmembrane structural domains with multiple phosphorylation sites. The drought stress-responsive R2R3-MYB gene, PmMYB4, was selected from the drought stress transcriptome based on analysis of the expression pattern and tissue specificity of PmMYB4 gene under abiotic stress using qPCR. The results showed that PmMYB4 can be involved in drought stress treatment through ABA signaling, as well as in multiple stress responses such as salt stress, and there were significant differences in the expression of PmMYB4 in the eight tissues. These results provide a reference scheme for the functional identification of R2R3-MYB transcription factors, which may be involved in plant responses to multiple stresses such as drought, and enrich our understanding of the functions of R2R3-MYB transcription factors in plants.