Transcriptome-wide identification and expression profiling of Pinus massoniana MYB transcription factors responding to phosphorus deficiency

Myeloblastosis (MYB) proteins constitute one of the largest transcription factor (TF) families in plants and play crucial roles in regulating plant physiological and biochemical processes, including adaptation to diverse abiotic stresses. These TF families contain highly conserved MYB repeats (1R, R2R3, 3R and 4R) at the N-terminus. Roles for MYB TFs have been reported in response to such stresses as dehydration, salt, cold, and drought. The characterization of Masson pine (Pinus massoniana) MYB TFs are reported, including the analysis of MYB TFs expression in seedlings under controlled conditions and two different phosphate (Pi) deficient treatments. By searching for conserved MYB motifs in full transcriptomic RNA sequencing data for P. massoniana, 59 sequences were identified as MYB TFs. Conserved domain structures and comparative functional and phylogenetic relationships of these MYB TFs with those in Arabidopsis were assessed using various bioinformatics tools. Based on microarray analysis, P. massoniana MYB genes exhibited different expression patterns under the two Pi deficiency conditions. Genes encoding MYB TFs that showed increased expression under critical Pi deficiency were identified, and some MYBs were differentially expressed only under conditions of severe Pi starvation. These results are useful for the functional characterization of MYB TFs that may be involved in the response to Pi deficiency and play divergent roles in plants.