Abstract
MYB proteins play important roles in the regulation of plant growth, development, and stress responses. Overexpression of BplMYB46 from Betula platyphylla improved plant salt and osmotic tolerances. In the present study, the interaction of eight avian myeloblastosis viral oncogene homolog (MYB) transcription factors with BplMYB46 was investigated using the yeast two-hybrid system, which showed that BplMYB46 could form homodimers and heterodimers with BplMYB6, BplMYB8, BplMYB11, BplMYB12, and BplMYB13. Relative beta-glucuronidase activity and chromatin immunoprecipitation assays showed that the interaction between BplMYB46 and the five MYBs increased the binding of BplMYB46 to the MYBCORE motif. A subcellular localization study showed that these MYBs were all located in the nucleus. Real-time fluorescence quantitative PCR results indicated that the expressions of BplMYB46 and the five MYB genes could be induced by salt and osmotic stress, and the BplMYB46 and BplMYB13 exhibited the most similar expression patterns. BplMYB46 and BplMYB13 co-overexpression in tobacco using transient transformation technology improved tobacco’s tolerance to salt and osmotic stresses compared with overexpressing BplMYB13 or BplMYB46 alone. Taken together, these results demonstrated that BplMYB46 could interact with five other MYBs to form heterodimers that activate the transcription of target genes via an enhanced binding ability to the MYBCORE motif to mediate reactive oxygen species scavenging in response to salt and osmotic stresses.
Highlights
The myeloblastosis viral oncogene homolog (MYB) family is one of the largest transcription factors (TFs) families in plants
Multiple sequence alignments of the eight MYB proteins with BplMYB46 protein from northeast white birch in China were performed to examine the structures of the MYB transcription factors (Figure S1)
The total RNA was treated with DNase I and was reverse transcribed into cDNA using a PrimeScriptTM Reverse Transcription (RT) reagent Kit (Takara Bio Inc.) and real-time PCR was performed for BplMYB46, BplMYB6, BplMYB8, BplMYB11, BplMYB12, and BplMYB13
Summary
The MYB family is one of the largest transcription factors (TFs) families in plants. MYBs have functions in various biological processes, such as regulating flavonoid biosynthesis, controlling cell differentiation, responding to hormone stimulus, mediating the cell wall biosynthesis, and enhancing or reducing biotic and abiotic stress tolerance of plants. MYB proteins share a conserved MYB DNA-binding domain that binds to cis-acting elements of transcription factor genes and a diverse C-terminal modulator region to regulate the protein’s activity. A study indicated that the MYB proteins interact with R/B-like bHLH proteins, jointly controlling the phenylpropanoid biosynthetic pathways, epidermal cell differentiation, and cell patterning in root hair or trichome development [15]. A previous study found that BplMYB46, an MYB gene from Betula Platyphylla (northeast white birch in China), enhances tolerance to salt and osmotic stresses when overexpressed in transgenic plants [20]. Our study provides insights into the important role of the interaction of BplMYB46 with other proteins in response to various stresses in plants
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