Involvement of VNS NAC-domain transcription factors in tracheid formation in Pinus taeda
Involvement of VNS NAC-domain transcription factors in tracheid formation in Pinus taeda
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DOI：
10.1093/treephys/tpz106
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发表时间：
2020-06-01
期刊：
影响因子：
4
通讯作者：
Demura, Taku
中科院分区：
文献类型：
--
作者：
Akiyoshi, Nobuhiro;Nakano, Yoshimi;Demura, Taku
维管植物有两种导水细胞，木质部导管细胞（被子植物）和管状细胞（蕨类植物和裸子植物）。这些细胞通常以次生细胞壁（SCW）形成和程序性细胞死亡（PCD）为特征，它们增加了水传导的效率。拟南芥木质部导管细胞的分化受一组NAC （NAM、ATAF1/2和CUC2）转录因子调控，这些转录因子被称为VASCULAR-RELATED NAC- domain （VND）家族。VNDs调节SCW形成和PCD所需基因的转录诱导。然而，关于管状细胞分化的转录调控的信息仍然有限。本研究对火炬松（Pinus taeda Linne） VND同源物（PtaVNS， VND, NST/SND， smb相关蛋白）进行了功能分析。在火炬松基因组中鉴定出5个PtaVNS基因，其中4个PtaVNS基因在管状细胞组织（如茎尖和发育中的木质部）中高表达。短暂过表达PtaVNS基因可诱导烟草叶片SCW沉积木质部血管样细胞模式，上调与SCW相关的MYB转录因子基因和纤维素合酶基因同源的火炬松基因启动子活性，以及PCD的半胱氨酸蛋白酶基因启动子活性。总的来说，我们的数据表明，PtaVNS蛋白具有转录活性，可以诱导气管形成所需的分子程序，即SCW形成和PCD。此外，这些发现表明，在被子植物和苔藓植物中，基于vns - myb的调节水传导细胞分化的转录网络在裸子植物中是保守的。
Vascular plants have two types of water-conducting cells, xylem vessel cells (in angiosperms) and tracheid cells (in ferns and gymnosperms). These cells are commonly characterized by secondary cell wall (SCW) formation and programmed cell death (PCD), which increase the efficiency of water conduction. The differentiation of xylem vessel cells is regulated by a set of NAC (NAM, ATAF1/2 and CUC2) transcription factors, called the VASCULAR-RELATED NAC-DOMAIN (VND) family, in Arabidopsis thaliana Linne. The VNDs regulate the transcriptional induction of genes required for SCW formation and PCD. However, information on the transcriptional regulation of tracheid cell differentiation is still limited. Here, we performed functional analysis of loblolly pine (Pinus taeda Linne) VND homologs (PtaVNS, for VND, NST/SND, SMB-related protein). We identified five PtaVNS genes in the loblolly pine genome, and four of these PtaVNS genes were highly expressed in tissues with tracheid cells, such as shoot apices and developing xylem. Transient overexpression of PtaVNS genes induced xylem vessel cell-like patterning of SCW deposition in tobacco (Nicotiana benthamiana Domin) leaves, and up-regulated the promoter activities of loblolly pine genes homologous to SCW-related MYB transcription factor genes and cellulose synthase genes, as well as to cysteine protease genes for PCD. Collectively, our data indicated that PtaVNS proteins possess transcriptional activity to induce the molecular programs required for tracheid formation, i.e., SCW formation and PCD. Moreover, these findings suggest that the VNS-MYB-based transcriptional network regulating water-conducting cell differentiation in angiosperm and moss plants is conserved in gymnosperms.