Yu Ying, Liu Huizi, Zhang Nan, Gao Caiqiu, Qi Liwang, Wang Chao
State Key Laboratory of Tree Genetics and Breeding, School of Forestry, Northeast Forestry University, Harbin, China.
Chinese Academy of Forestry, Beijing, China.
Front Plant Sci. 2021 Jan 18;11:606062. doi: 10.3389/fpls.2020.606062. eCollection 2020.
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 ( Suk.) and homologous to EgMYB1 from Smith and ZmMYB31 from L. is involved in secondary cell wall synthesis. The expression level of 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. also was induced express by abiotic stress. Functional analysis indicated that expression of in transgenic Arabidopsis () 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 could scavenge hydrogen peroxide and O 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禽成髓细胞瘤病毒癌基因同源物）家族是植物中最大的转录因子家族之一，广泛参与植物代谢的调控。在本研究中，我们发现从桦树（Suk.）中鉴定出的一种MYB4转录因子BpMYB4，与史密斯的EgMYB1和L.的ZmMYB31同源，参与次生细胞壁合成。相对于其他组织，其在花中的表达水平更高，并且在发育中的木质部组织中受到人工弯曲和重力刺激的诱导。该基因的表达在生长活跃季节的发育中的木质部中不富集，在发芽期和休眠期附近的木质部组织中显示出较高的转录水平。它也受到非生物胁迫的诱导表达。功能分析表明，在转基因拟南芥（）植物中表达可促进茎的生长，并导致花序茎和枝条数量增加。茎段的解剖观察显示木质素沉积减少，化学含量测试也表明转基因植物中纤维素含量增加而木质素含量降低。此外，用100 mM NaCl和200 mM甘露醇处理导致过表达系的发芽率高于野生型种子。转基因植物中的脯氨酸含量高于野生型，但丙二醛含量低于野生型。使用瞬时转化技术在桦树中的进一步研究表明，与野生型植物相比，过表达可清除过氧化氢和O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的发育和纤维素生物合成，并在非生物胁迫抗性中发挥作用。
