EgMYB2, a new transcriptional activator from Eucalyptus xylem, regulates secondary cell wall formation and lignin biosynthesis
EgMYB2, a new transcriptional activator from Eucalyptus xylem, regulates secondary cell wall formation and lignin biosynthesis
复制标题
DOI：
10.1111/j.1365-313x.2005.02480.x
复制
发表时间：
2005-08-01
期刊：
影响因子：
7.2
通讯作者：
Grima-Pettenati, J
中科院分区：
文献类型：
--
作者：
Goicoechea, M;Lacombe, E;Grima-Pettenati, J
EgMYB2 是 R2R3 MYB 转录因子家族新亚组的成员，是从由分化桉树木质部的 RNA 组成的文库中克隆出来的。 EgMYB2 映射到巨桉连锁图上的一个独特基因座，并与木质素含量的数量性状基因座 (QTL) 共定位。重组 EgMYB2 蛋白能够特异性结合两个木质素生物合成基因肉桂酰辅酶 A 还原酶 (CCR) 和肉桂醇脱氢酶 (CAD) 启动子的顺式调控区域，其中包含 MYB 共有结合位点。 EgMYB2 还能够在瞬时表达和稳定表达测定中调节其转录。过度表达 EgMYB2 的转基因烟草植物相对于野生型植物表现出表型变化，其中包括次生细胞壁厚度的显着增加和木质素谱的改变。根据途径中各个基因的位置，编码木质素生物合成特异性酶的基因的转录本丰度有不同程度的增加，而核心苯丙素基因没有受到显着影响。总之，这些结果表明 EgMYB2 在属于木质素单体特异性途径的基因的协调控制中发挥作用，因此在木质素的生物合成和次生细胞壁形成的调节中发挥作用。
EgMYB2, a member of a new subgroup of the R2R3 MYB family of transcription factors, was cloned from a library consisting of RNA from differentiating Eucalyptus xylem. EgMYB2 maps to a unique locus on the Eucalyptus grandis linkage map and co-localizes with a quantitative trait locus (QTL) for lignin content. Recombinant EgMYB2 protein was able to bind specifically the cis-regulatory regions of the promoters of two lignin biosynthetic genes, cinnamoyl-coenzyme A reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD), which contain MYB consensus binding sites. EgMYB2 was also able to regulate their transcription in both transient and stable expression assays. Transgenic tobacco plants over-expressing EgMYB2 displayed phenotypic changes relative to wild-type plants, among which were a dramatic increase in secondary cell wall thickness, and an alteration of the lignin profiles. Transcript abundance of genes encoding enzymes specific to lignin biosynthesis was increased to varying extents according to the position of individual genes in the pathway, whereas core phenylpropanoid genes were not significantly affected. Together these results suggest a role for EgMYB2 in the co-ordinated control of genes belonging to the monolignol-specific pathway, and therefore in the biosynthesis of lignin and the regulation of secondary cell wall formation.