Starke Michał D, Kapusta Małgorzata, Płachno Bartosz J, Bohdanowicz Jerzy
Laboratory of Plant Cytology and Embryology, Department of Plant Experimental Biology and Biotechnology, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza St., 80-308 Gdansk, Poland.
Bioimaging Laboratory, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza St., 80-308 Gdansk, Poland.
Cells. 2024 Nov 30;13(23):1985. doi: 10.3390/cells13231985.
(L.) Rich, an endangered member of the Orchidaceae family, is found in alkaline fens. With the declining populations of , there is a pressing need to reintroduce this species in Central Europe. As in vitro germination is a crucial tool for obtaining plants for introduction into the environment, we looked at the morphological changes occurring during the early stages of development in vitro. As the early stages of orchid development, especially the protocorm stage, are thought to be responsible for SAM formation and the initiation of symbiotic association, we focused on cell wall elements whose epitopes have been found in similar processes in other species: the extensin and pectin rhamnogalacturonan I (RG-I) side chain epitopes. We addressed the following questions: Does the cell wall of change its composition during the early stages of development, as noted in other species? Are there noticeable similarities in the cell wall to organs of different species whose function is to contact microorganisms? Are there regularities that allow the recognition of individual structures on this basis? Immunolocalization revealed changes in the distribution of certain extensins (JIM11 and JIM20) and RG-I (LM5 and LM6) side chain epitopes. Extensins, a type of cell wall protein, were observed during the initial stages of the formation of PLB and the shoot apical meristem of protocorms and PLBs. RG-I, on the other hand, was found to play a significant role in the development of the protocorm and PLB. In pseudobulbs, which appeared on the protocorms, extensins occurred in their storage part. However, RG-I side chains (1→4)-β-galactans (LM5), and (1→5)-α-L-arabinans (LM6) were not found in pseudobulbs. We revealed that a common feature of protocorms and PLBs was an increased amount of extensins, which were detected with the JIM11 antibody, and pectins, which were detected with the LM5 antibody, that were present together, which may prove helpful in determining the identity of the induced structures and distinguishing them from pseudobulbs. Thus, our study unveiled the role of extensins and RG-I during the growth of protocorms and PLBs. We suggest that PLBs may mimic the wall remodelling that occurs in protocorms, which indicates that using cell wall components is an invitation to be colonised by a fungal partner. However, this needs to be tested in future research. The findings of this research can help interpret future studies on the propagation, acclimatisation, and introduction of into the natural environment.
罗氏兜兰（L. Rich）是兰科的一种濒危植物，生长在碱性沼泽地。随着其种群数量的减少，在中欧重新引入该物种的需求迫在眉睫。由于离体萌发是获取用于引入环境的植物的关键工具，我们研究了罗氏兜兰在离体发育早期阶段发生的形态变化。由于兰花发育的早期阶段，尤其是原球茎阶段，被认为负责茎尖分生组织的形成和共生关系的启动，我们关注了其细胞壁成分，这些成分的表位在其他物种的类似过程中已被发现：伸展蛋白和果胶鼠李半乳糖醛酸聚糖I（RG-I）侧链表位。我们提出了以下问题：罗氏兜兰的细胞壁在发育早期阶段是否会像其他物种那样改变其组成？其细胞壁与不同物种中负责与微生物接触的器官是否存在明显的相似性？是否存在基于此识别个体结构的规律？免疫定位揭示了某些伸展蛋白（JIM11和JIM20）以及RG-I（LM5和LM6）侧链表位分布的变化。伸展蛋白是一种细胞壁蛋白，在原球茎和原球茎状小块茎的类原球茎和茎尖分生组织形成的初始阶段被观察到。另一方面，发现RG-I在原球茎和原球茎状小块茎的发育中起重要作用。在原球茎上出现的假鳞茎中，伸展蛋白存在于其储存部分。然而，在假鳞茎中未发现RG-I侧链（1→4）-β-半乳聚糖（LM5）和（1→5）-α-L-阿拉伯聚糖（LM6）。我们发现原球茎和原球茎状小块茎的一个共同特征是，用JIM11抗体检测到的伸展蛋白和用LM5抗体检测到的果胶的含量增加，它们共同存在，这可能有助于确定诱导结构的身份并将其与假鳞茎区分开来。因此，我们的研究揭示了伸展蛋白和RG-I在原球茎和原球茎状小块茎生长过程中的作用。我们认为原球茎状小块茎可能模拟了原球茎中发生的细胞壁重塑，这表明利用细胞壁成分可能会吸引真菌伙伴进行定殖。然而，这需要在未来的研究中进行验证。本研究结果有助于解释未来关于罗氏兜兰繁殖、驯化以及引入自然环境的研究。
