PtoMYB170 positively regulates lignin deposition during wood formation in poplar and confers drought tolerance in transgenic Arabidopsis
PtoMYB170 positively regulates lignin deposition during wood formation in poplar and confers drought tolerance in transgenic Arabidopsis
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DOI：
10.1093/treephys/tpx093
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发表时间：
2017-12
期刊：
影响因子：
4
通讯作者：
Changzheng Xu;Xiaokang Fu;Rui Liu;Li Guo;Lingyu Ran;Chaofeng Li;Qiaoyan Tian;Bo Jiao;Bangjun Wan
中科院分区：
文献类型：
--
作者：
Changzheng Xu;Xiaokang Fu;Rui Liu;Li Guo;Lingyu Ran;Chaofeng Li;Qiaoyan Tian;Bo Jiao;Bangjun Wan
木材形成是在大量转录因子执行的多级转录控制下的复杂发育过程。然而，只有有限的成员被认为是杨树木质素生物合成的关键调节因子。在这里，我们报告了 PtoMYB170（一种从毛白杨中鉴定出的转录因子）在木质素沉积和耐旱性方面与其重复旁系同源 PtoMYB216 相比的保守且独特的功能。 PtoMYB170 优先在幼叶和木质部组织中表达。与野生型植物相比，转基因杨植物中 PtoMYB170 的过度表达导致木质部木质化更强、次生壁更厚，而 CRISPR/Cas9 产生的 PtoMYB170 突变削弱了木质素沉积，从而导致木质部更加灵活和塌陷的表型。瞬时表达实验表明，PtoMYB170 特异性激活木质素生物合成基因的表达，与 PtoMYB216 的功能一致。然而，GUS 染色分析显示，PtoMYB170 在转基因拟南芥的保卫细胞中特异性表达，而 PtoMYB216 则不然。 PtoMYB170 在拟南芥中的异源表达增强了黑暗中气孔的关闭，并通过减少水分流失导致转基因植物的耐旱性，这表明 PtoMYB216 的多样化作用。这些结果揭示了 PtoMYB170 对杨树木质素沉积的正转录调控及其通过促进暗诱导气孔关闭来增强耐旱性的协调功能。
Wood formation is a complex developmental process under multi-level transcriptional control executed by a large set of transcription factors. However, only limited members have been characterized to be key regulators of lignin biosynthesis in poplar. Here we report the conserved and unique functions of PtoMYB170, a transcription factor identified from Populus tomentosa (Chinese white poplar), in lignin deposition and drought tolerance in comparison with its duplicate paralog PtoMYB216. PtoMYB170 is preferentially expressed in young leaves and xylem tissues. Overexpression of PtoMYB170 in transgenic poplar plants resulted in stronger lignification and more thickened secondary wall in xylem compared with wild-type plants, whereas the CRISPR/Cas9-generated mutation of PtoMYB170 weakened lignin deposition, thereby leading to a more flexible and collapsed xylem phenotype. Transient expression experiments demonstrated that PtoMYB170 specifically activated the expression of lignin biosynthetic genes, consistent with the function of PtoMYB216. However, GUS staining assays revealed that PtoMYB170 was specifically expressed in guard cells of transgenic Arabidopsis while PtoMYB216 was not. Heterologous expression of PtoMYB170 in Arabidopsis enhanced stomatal closure in the dark and resulted in drought tolerance of the transgenic plants through reduced water loss, indicating a diversified role from PtoMYB216. These results revealed the PtoMYB170-dependent positive transcriptional regulation on lignin deposition in poplar and its coordinated function in enhancing drought tolerance by promoting dark-induced stomatal closure.