The MYB (v-myb avian myeloblastosis viral oncogene homolog) family is one of the largest transcription factor families in plants, and is widely involved in the regulation of plant metabolism. In this study, we show that a MYB4 transcription factor, BpMYB4, identified from birch (Betula platyphylla Suk.) and homologous to EgMYB1 from Eucalyptus robusta Smith and ZmMYB31 from Zea mays L. is involved in secondary cell wall synthesis. The expression level of BpMYB4 was higher in flowers relative to other tissues, and was induced by artificial bending and gravitational stimuli in developing xylem tissues. The expression of this gene was not enriched in the developing xylem during the active season, and showed higher transcript levels in xylem tissues around sprouting and near the dormant period. BpMYB4 also was induced express by abiotic stress. Functional analysis indicated that expression of BpMYB4 in transgenic Arabidopsis (Arabidopsis thaliana) plants could promote the growth of stems, and result in increased number of inflorescence stems and shoots. Anatomical observation of stem sections showed lower lignin deposition, and a chemical contents test also demonstrated increased cellulose and decreased lignin content in the transgenic plants. In addition, treatment with 100 mM NaCl and 200 mM mannitol resulted in the germination rate of the over-expressed lines being higher than that of the wild-type seeds. The proline content in transgenic plants was higher than that in WT, but MDA content was lower than that in WT. Further investigation in birch using transient transformation techniques indicated that overexpression of BpMYB4 could scavenge hydrogen peroxide and O₂^.– and reduce cell damage, compared with the wild-type plants. Therefore, we believe that BpMYB4 promotes stem development and cellulose biosynthesis as an inhibitor of lignin biosynthesis, and has a function in abiotic stress resistance.

MYB（v-myb禽成纤维细胞病病毒致癌基因同源物）家族是植物中最大的转录因子家族之一，并且广泛参与植物代谢的调节。在这项研究中，我们显示了从桦木中鉴定出的MYB4转录因子BpMYB4（白桦 Suk。），与来自的EgMYB1同源 桉树 来自的Smith和ZmMYB31 玉米L.参与二次细胞壁合成。表达水平BpMYB4相对于其他组织而言，花中的这种氨基酸含量更高，并且是由发育中的木质部组织中的人工弯曲和重力刺激诱导的。该基因的表达在活跃季节未在发展中的木质部中富集，并且在发芽前后和休眠期附近的木质部组织中显示出更高的转录水平。BpMYB4非生物胁迫也诱导表达。功能分析表明BpMYB4 在转基因拟南芥中拟南芥）植物可以促进茎的生长，并导致花序茎和芽的数量增加。茎部的解剖观察表明，木质素沉积降低，​​化学含量测试还表明，转基因植物中纤维素增加，木质素含量降低。另外，用100mM NaCl和200mM甘露糖醇处理导致过表达品系的发芽率高于野生型种子的发芽率。转基因植物中脯氨酸的含量高于野生型，而丙二醛的含量低于野生型。桦木中使用瞬时转化技术的进一步研究表明，桦木的过表达BpMYB4与野生型植物相比，可以清除过氧化氢和O ₂ ^.-并减少细胞损伤。因此，我们认为BpMYB4作为木质素生物合成的抑制剂促进茎发育和纤维素生物合成，并且在非生物胁迫抗性中起作用。