Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan.
Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan.
Planta. 2021 Apr 13;253(5):99. doi: 10.1007/s00425-021-03621-4.
Calli derived from young leaves of Aesculus turbinata contained tracheary elements with large pores that resembled perforations of vessel elements. The differentiation of tracheary elements in vitro provides a useful system for detailed analysis of xylem cell differentiation. To examine the mechanism of formation of cell wall structures, new differentiation systems are required that allows us to induce highly organized structures, such as perforations. In this study, we developed such a system in which we were able to induce formation of tracheary elements with perforations, using calli of a hardwood, Aesculus turbinata. Young leaves of A. turbinata were placed on modified MS medium that contained 5 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 5 μM benzyladenine (BA). Tracheary elements were induced in calli derived from young leaves of A. turbinata. Some tracheary elements formed broad areas of secondary wall with typical features of secondary xylem. Other tracheary elements formed spiral thickenings, which are typical features of vessel elements in secondary xylem of A. turbinata. Approximately 10% of tracheary elements formed large pores that resembled perforations of vessel elements and various types of the perforation plate were observed. Addition of NAA and brassinolide to the induction medium enhanced the differentiation of tracheary elements in calli of A. turbinata. Newly induced tracheary elements also formed typical features of secondary xylem such as perforations of the vessel elements. Our model system might be useful in efforts to understand the mechanisms of formation of highly organized structures in tracheary elements in secondary xylem.
来源于青榨槭幼叶的愈伤组织中含有具大孔的导管分子，这些大孔类似于导管分子的穿孔。体外培养的导管分子分化为详细分析木质部细胞分化提供了一个有用的系统。为了研究细胞壁结构形成的机制，需要新的分化系统，允许我们诱导高度组织化的结构，如穿孔。在这项研究中，我们开发了这样一个系统，使用硬木青榨槭的愈伤组织，我们能够诱导具有穿孔的导管分子的形成。将青榨槭的幼叶放置在改良的 MS 培养基上，该培养基含有 5 μM 2,4-二氯苯氧乙酸（2,4-D）和 5 μM 苄基腺嘌呤（BA）。在青榨槭幼叶的愈伤组织中诱导出导管分子。一些导管分子在次生壁上形成宽阔的区域，具有次生木质部的典型特征。其他导管分子形成螺旋加厚，这是青榨槭次生木质部中导管分子的典型特征。大约 10%的导管分子形成类似于导管分子穿孔的大孔，观察到各种类型的穿孔板。在诱导培养基中添加 NAA 和油菜素内酯可增强青榨槭愈伤组织中导管分子的分化。新诱导的导管分子也形成了次生木质部的典型特征，如导管分子的穿孔。我们的模型系统可能有助于理解次生木质部中导管分子中高度组织化结构形成的机制。
