Kamon Eri, Noda Chihiro, Higaki Takumi, Demura Taku, Ohtani Misato
Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8562, Japan.
Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.
Plant Biotechnol (Tokyo). 2021 Sep 25;38(3):331-337. doi: 10.5511/plantbiotechnology.21.0519a.
Secondary cell walls (SCWs) accumulate in specific cell types of vascular plants, notably xylem vessel cells. Previous work has shown that calcium ions (Ca) participate in xylem vessel cell differentiation, but whether they function in SCW deposition remains unclear. In this study, we examined the role of Ca in SCW deposition during xylem vessel cell differentiation using suspension-cultured cells carrying the VND7-inducible system, in which VND7 activity can be post-translationally upregulated to induce transdifferentiation into protoxylem-type vessel cells. We observed that extracellular Ca concentration was a crucial determinant of differentiation, although it did not have consistent effects on the transcription of VND7-downstream genes as a whole. Increasing the Ca concentration reduced differentiation but the cells could generate the spiral patterning of SCWs. Exposure to a calcium-channel inhibitor partly restored differentiation but resulted in abnormal branched and net-like SCW patterning. These data suggest that Ca signaling participates in xylem vessel cell differentiation via post-transcriptional regulation of VND7-downstream events, such as patterning of SCW deposition.
次生细胞壁（SCWs）在维管植物的特定细胞类型中积累，尤其是木质部导管细胞。先前的研究表明，钙离子（Ca）参与木质部导管细胞的分化，但它们是否在SCW沉积中发挥作用仍不清楚。在本研究中，我们使用携带VND7诱导系统的悬浮培养细胞，研究了Ca在木质部导管细胞分化过程中SCW沉积中的作用，在该系统中，VND7活性可以在翻译后上调，以诱导转分化为原生木质部型导管细胞。我们观察到细胞外Ca浓度是分化的关键决定因素，尽管它对VND7下游基因的整体转录没有一致的影响。增加Ca浓度会降低分化，但细胞可以产生SCWs的螺旋模式。暴露于钙通道抑制剂部分恢复了分化，但导致了异常的分支和网状SCW模式。这些数据表明，Ca信号通过对VND7下游事件（如SCW沉积模式）的转录后调控参与木质部导管细胞的分化。
