Complexity of the transcriptional network controlling secondary wall biosynthesis.
Complexity of the transcriptional network controlling secondary wall biosynthesis.
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DOI：
10.1016/j.plantsci.2014.09.009
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发表时间：
2014-12
期刊：
影响因子：
--
通讯作者：
R. Zhong;Z. Ye
中科院分区：
文献类型：
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作者：
R. Zhong;Z. Ye
木材和纤维形式的次生壁是维管植物产生的最丰富的生物质，是许多工业用途的重要原材料。了解次生壁的构建方式对于基础植物生物学具有重要意义，并且对于更适合各种最终用途（例如生物燃料生产）的植物生物质的基因工程也具有深远的影响。次生壁由三种主要生物聚合物组成，即纤维素、半纤维素和木质素，其生物合成需要其所有生物合成基因的协调转录调控。基因组和分子研究已经确定了许多转录因子，其表达与次生壁生物合成相关。我们全面回顾了这些次生壁相关转录因子如何共同发挥作用以开启次生壁生物合成程序，从而导致维管植物中的次生壁沉积。调控次生壁生物合成的转录网络采用多级前馈环调节结构，其中顶层次生壁NAC（NAM、ATAF1/2和CUC2）主开关激活二级MYB主开关，它们共同诱导下游转录因子和次生壁生物合成基因的表达。次生壁NAC主开关和次生壁MYB主开关分别结合并激活其靶基因启动子中的SNBE（次生壁NAC结合元件）和SMRE（次生壁MYB响应元件）位点。进一步研究发育信号是什么以及如何触发转录网络来调节次生壁生物合成，以及不同的次生壁相关转录因子如何在激活次生壁生物合成途径中协同发挥作用，将有助于更好地理解次生壁生物合成转录控制的分子机制。
Secondary walls in the form of wood and fibers are the most abundant biomass produced by vascular plants, and are important raw materials for many industrial uses. Understanding how secondary walls are constructed is of significance in basic plant biology and also has far-reaching implications in genetic engineering of plant biomass better suited for various end uses, such as biofuel production. Secondary walls are composed of three major biopolymers, i.e., cellulose, hemicelluloses and lignin, the biosynthesis of which requires the coordinated transcriptional regulation of all their biosynthesis genes. Genomic and molecular studies have identified a number of transcription factors, whose expression is associated with secondary wall biosynthesis. We comprehensively review how these secondary wall-associated transcription factors function together to turn on the secondary wall biosynthetic program, which leads to secondary wall deposition in vascular plants. The transcriptional network regulating secondary wall biosynthesis employs a multi-leveled feed-forward loop regulatory structure, in which the top-level secondary wall NAC (NAM, ATAF1/2 and CUC2) master switches activate the second-level MYB master switches and they together induce the expression of downstream transcription factors and secondary wall biosynthesis genes. Secondary wall NAC master switches and secondary wall MYB master switches bind to and activate the SNBE (secondary wall NAC binding element) and SMRE (secondary wall MYB-responsive element) sites, respectively, in their target gene promoters. Further investigation of what and how developmental signals trigger the transcriptional network to regulate secondary wall biosynthesis and how different secondary wall-associated transcription factors function cooperatively in activating secondary wall biosynthetic pathways will lead to a better understanding of the molecular mechanisms underlying the transcriptional control of secondary wall biosynthesis.