Characteristic thickened cell walls of the bracts of the 'eternal flower' Helichrysum bracteatum.
Characteristic thickened cell walls of the bracts of the 'eternal flower' Helichrysum bracteatum.
复制标题
“永生花”蜡菊苞片特有的增厚细胞壁。
DOI：
10.1093/aob/mcn058
复制
发表时间：
2008
期刊：
影响因子：
4.2
通讯作者：
S. Yazawa
中科院分区：
文献类型：
--
作者：
Kuniko Nishikawa;Hiroaki Ito;T. Awano;M. Hosokawa;S. Yazawa
背景与目的
Helichrysum bracteatum被称为“永恒的花”，有大，彩色，干膜质的苞片。这些保持其美学价值没有枯萎或变色多年。目前还没有关于干膜质苞片的细胞死亡或细胞形态的研究，因此本工作的目的是阐明H.苞片
方法
用DAPI（4 '6-diamidino-2-phenylindol dihydrochloride）染色和荧光显微镜观察细胞核。采用光学显微镜（LM）、透射电子显微镜（TEM）和偏振光显微镜观察细胞，包括细胞壁形态。
关键成果
在花发育的早期，苞片顶端细胞死亡。细胞壁是H.苞片细胞。在表皮细胞和内层细胞中，观察到初生细胞壁内侧的特征性加厚的次生细胞壁。此外，所有细胞的细胞壁都表现出双折射。特征性加厚的次生细胞壁具有定向纤维素微纤丝以及导管分子的一般次生细胞壁。而在菊花的花瓣和苞片组织中没有观察到这些性状。
结论
开花期苞片由死细胞组成。蜡菊苞片具有在任何其它花或叶的薄壁组织中未观察到的特征性加厚的次生细胞壁。H.苞片不同于其它具有次生细胞壁的组织，可能是一种新的细胞类型。
BACKGROUND AND AIMS
Helichrysum bracteatum is called an 'eternal flower' and has large, coloured, scarious bracts. These maintain their aesthetic value without wilting or discoloration for many years. There have been no research studies of cell death or cell morphology of the scarious bract, and hence the aim of this work was to elucidate these characteristics for the bract of H. bracteatum.
METHODS
DAPI (4'6-diamidino-2-phenylindol dihydrochloride) staining and fluorescence microscopy were used for observation of cell nuclei. Light microscopy (LM), transmission electron microscopy (TEM) and polarized light microscopy were used for observation of cells, including cell wall morphology.
KEY RESULTS
Cell death occurred at the bract tip during the early stage of flower development. The cell wall was the most prominent characteristic of H. bracteatum bract cells. Characteristic thickened secondary cell walls on the inside of the primary cell walls were observed in both epidermal and inner cells. In addition, the walls of all cells exhibited birefringence. Characteristic thickened secondary cell walls have orientated cellulose microfibrils as well as general secondary cell walls of the tracheary elements. For comparison, these characters were not observed in the petal and bract tissues of Chrysanthemum morifolium.
CONCLUSIONS
Bracts at anthesis are composed of dead cells. Helichrysum bracteatum bracts have characteristic thickened secondary cell walls that have not been observed in the parenchyma of any other flowers or leaves. The cells of the H. bracteatum bract differ from other tissues with secondary cell walls, suggesting that they may be a new cell type.