Cotton GhMYB7 is predominantly expressed in developing fibers and regulates secondary cell wall biosynthesis in transgenic Arabidopsis
Cotton GhMYB7 is predominantly expressed in developing fibers and regulates secondary cell wall biosynthesis in transgenic Arabidopsis
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棉花 GhMYB7 主要在发育中的纤维中表达，并调节转基因拟南芥中的次生细胞壁生物合成
DOI：
10.1007/s11427-015-4991-4
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发表时间：
2016-02-01
影响因子：
9.1
通讯作者：
Xu, Wenliang
中科院分区：
文献类型：
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作者：
Huang, Junfeng;Chen, Feng;Xu, Wenliang
成熟棉纤维中的次生细胞壁含有90%以上的纤维素和少量的木聚糖和木质素。然而，关于棉纤维次生细胞壁生物合成的调控知之甚少。在这项研究中，我们表征了棉花中的R2 R3-MYB转录因子GhMYB 7。GhMYB 7在发育中的纤维中高水平表达，编码靶向细胞核并具有转录激活活性的MYB蛋白。GhMYB 7在拟南芥中的异位表达导致小的、卷曲的、深绿色的叶子，并且还导致较短的花序茎。基茎的横截面分析显示，细胞壁厚度的血管和束间纤维是高过表达GhMYB 7的转基因株系比野生型。GhMYB 7在拟南芥中的组成型表达激活了一系列次生细胞壁生物合成相关基因（包括一些次生细胞壁相关转录因子）的表达，导致纤维素和木质素的异位沉积。次生细胞壁的异位沉积可能在细胞扩展停止之前就已经开始了。此外，GhMYB 7能够结合到AtSND 1和AtCesA 4的启动子区，这表明GhMYB 7可能在NAC转录因子的上游发挥作用。综上所述，GhMYB 7可能是一个潜在的转录激活因子，参与调控棉纤维次生细胞壁的生物合成。
The secondary cell wall in mature cotton fibers contains over 90% cellulose with low quantities of xylan and lignin. However, little is known regarding the regulation of secondary cell wall biosynthesis in cotton fibers. In this study, we characterized an R2R3-MYB transcription factor, GhMYB7, in cotton. GhMYB7 is expressed at a high level in developing fibers and encodes a MYB protein that is targeted to the cell nucleus and has transcriptional activation activity. Ectopic expression of GhMYB7 in Arabidopsis resulted in small, curled, dark green leaves and also led to shorter inflorescence stems. A cross-sectional assay of basal stems revealed that cell wall thickness of vessels and interfascicular fibers was higher in transgenic lines overexpressing GhMYB7 than in the wild type. Constitutive expression of GhMYB7 in Arabidopsis activated the expression of a suite of secondary cell wall biosynthesis-related genes (including some secondary cell wall-associated transcription factors), leading to the ectopic deposition of cellulose and lignin. The ectopic deposition of secondary cell walls may have been initiated before the cessation of cell expansion. Moreover, GhMYB7 was capable of binding to the promoter regions of AtSND1 and AtCesA4, suggesting that GhMYB7 may function upstream of NAC transcription factors. Collectively, these findings suggest that GhMYB7 is a potential transcriptional activator, which may participate in regulating secondary cell wall biosynthesis of cotton fibers.