牡丹愈伤组织发生和分生结节形成的细胞组织学研究

Cytohistological Studies on the Callus Genesis and Meristematic Nodule Formation of Paeonia×lemoinei ‘Golden era’

以牡丹‘Golden era’叶柄薄层为外植体,结合外部形态,对愈伤组织发生,并分化为分生结节过程进行了细胞组织学研究,为进一步研究牡丹不定器官分化、实现离体微繁殖奠定基础。结果表明:愈伤组织的发生与发育经历了启动、分裂、形成和组织分化4个时期。启动期,外植体束中形成层最先去分化,表现为形态上变暗,内部细胞核变大,淀粉代谢增强。细胞旺盛增殖的分裂期,先后于外植体形成层和皮层薄壁细胞处产生了愈伤组织,形成了质地紧实的愈伤增殖团,愈伤细胞体积小、质浓、核位于中心,且具有绕核积累的淀粉粒。形成期,愈伤组织增殖速度减缓,只有接触培养基的周缘愈伤组织仍在增殖。组织分化期,愈伤组织内部分化出维管单元,可以作为生长中心,有的是以特化的薄壁细胞为生长中心,外围核大、质浓的薄壁细胞层形成了具有再生潜能的分生结节。

The genesis and differentiation into meristematic nodule of thin cell layer of （TCLs） petiole callus in modern tree peony ＇Golden era＇ were studied. The results showed that there were four stages in the course of callus development, namely activation, division, formation and histodifferentiation. During activation, fascicular cambium cells were most notable, showing brown externally and bigger cells, clear and nearcenter nucleus internally. Meanwhile the starch metabolic enhanced. Cells kept division during the second stage division and led to the formation of callus in cambial area firstly and then in the region of cortex parenchyma cells. These callus tissues formed a compact cell cluster and the callus cells were characterized by dense cytoplasm, nucleus in center, small in volume and starch grains accumulated around the nucleus. However,callus proliferated at a slower rate during formation stage,only the peripheral callus cells which facing the medium kept division. At the last stage histodifferentiation, callus tissues differentiated into neoformed tracheary elements. Some of these tracheids organized as vascular centers and some specialized parenchyma cells could also act as centers. And then these centers were surrounded by loosely arranged, plastid-dense cell layers. This way,meristematic nodule formed which was thought to be potential in mass production. The result here can be used as a basis for further improvement of organ regeneration system forlarge-scale multiplication of tree peony.