Genome-wide transcriptional profiling reveals molecular signatures of secondary xylem differentiation in Populus tomentosa.
Genome-wide transcriptional profiling reveals molecular signatures of secondary xylem differentiation in Populus tomentosa.
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DOI：
10.4238/2014.november.11.14
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发表时间：
2014-11
期刊：
影响因子：
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通讯作者：
Xiaohui Yang;Xinguo Li;Bailian Li;Deqiang Zhang
中科院分区：
文献类型：
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作者：
Xiaohui Yang;Xinguo Li;Bailian Li;Deqiang Zhang
木材的形成是通过维管形成层中的细胞分裂、初生壁和次生壁的形成以及细胞程序性死亡来进行的。次生木质部分化的转录谱分析对于理解木材形成的分子机制至关重要。利用基因芯片技术研究了杨树次生木质部分化过程中基因的差异表达。然而，从全基因组的角度对分子机制知之甚少。本研究利用含有61，413个探针的毛白杨基因组芯片，研究了毛白色杨次生木质部分化过程中转录组的变化。对两种木质部组织（新形成的和木质部）进行取样用于全基因组转录谱分析。在两种木质部组织中，共鉴定出6843个差异表达基因（约11%）。许多参与细胞分裂，初生壁修饰和纤维素合成的基因优先在新形成的木质部中表达。与此相反，许多基因，包括4-香豆酸：肉桂酸-4-羟化酶（C4 H），4-香豆酸：CoA连接酶（4CL），肉桂醇脱氢酶（CAD），和咖啡酰CoA 3-O-甲基转移酶（CCoAOMT），与木质素生物合成更多的转录在木质部。两种木质部组织中不同激素相关基因的表达也存在差异，说明次生木质部的分化可能受激素信号的调控。此外，许多转录因子基因在木质部中优先表达，表明木材木质化涉及广泛的转录调控。次生木质部分化的全基因组转录谱分析可以为白杨木材形成的分子基础提供更多的信息。
Wood formation occurs via cell division, primary cell wall and secondary wall formation, and programmed cell death in the vascular cambium. Transcriptional profiling of secondary xylem differentiation is essential for understanding the molecular mechanisms underlying wood formation. Differential gene expression in secondary xylem differentiation of Populus has been previously investigated using cDNA microarray analysis. However, little is known about the molecular mechanisms from a genome-wide perspective. In this study, the Affymetrix poplar genome chips containing 61,413 probes were used to investigate the changes in the transcriptome during secondary xylem differentiation in Chinese white poplar (Populus tomentosa). Two xylem tissues (newly formed and lignified) were sampled for genome-wide transcriptional profiling. In total, 6843 genes (~11%) were identified with differential expression in the two xylem tissues. Many genes involved in cell division, primary wall modification, and cellulose synthesis were preferentially expressed in the newly formed xylem. In contrast, many genes, including 4-coumarate:cinnamate-4-hydroxylase (C4H), 4-coumarate:CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD), and caffeoyl CoA 3-O-methyltransferase (CCoAOMT), associated with lignin biosynthesis were more transcribed in the lignified xylem. The two xylem tissues also showed differential expression of genes related to various hormones; thus, the secondary xylem differentiation could be regulated by hormone signaling. Furthermore, many transcription factor genes were preferentially expressed in the lignified xylem, suggesting that wood lignification involves extensive transcription regulation. The genome-wide transcriptional profiling of secondary xylem differentiation could provide additional insights into the molecular basis of wood formation in poplar species.