Wu Xiaoqin, Lin Jinxing, Lin Qingqing, Wang Jian, Schreiber Lukas
Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing.
Plant Cell Physiol. 2005 Nov;46(11):1799-808. doi: 10.1093/pcp/pci194. Epub 2005 Sep 17.
The structure and development of endodermal Casparian strips in Pinus bungeana needles and roots were studied by scanning electron microscopy and fluorescence microscopy. Primary pit fields (PFs) frequently occurred in radial walls of Casparian strips isolated from needles, whereas PFs were never detected in Casparian strips from roots. Formation of Casparian strips in needles as well as roots started at the outer parts of the radial walls and they finally occupied the entire radial walls of the endodermis. Fourier transform infrared (FTIR) spectroscopy of Casparian strips isolated from roots revealed significant absorption bands characteristic for suberin. However, in Casparian strips of needles, evidence for suberin was rarely detected by FTIR spectroscopy. The apoplastic permeability of Casparian strips in needles and roots was probed by the apoplastic tracers calcofluor and berberine. Casparian strips in roots efficiently blocked the apoplastic transport (AT) of calcofluor and berberine. Casparian strips in needles blocked the AT of calcofluor, but diffusion of berberine was not inhibited and berberine thiocyanate crystals were detectable in the vascular tissue of the needles. From the data presented, it must be concluded that Casparian strips in needles, which are characterized by the absence of suberin, are more solute permeable compared with Casparian strips in roots.
通过扫描电子显微镜和荧光显微镜研究了白皮松针叶和根中内皮层凯氏带的结构与发育。从针叶分离出的凯氏带径向壁上频繁出现初生纹孔场（PFs），而从根中分离出的凯氏带中从未检测到PFs。针叶和根中凯氏带的形成均始于径向壁的外部，最终占据了内皮层的整个径向壁。对从根中分离出的凯氏带进行傅里叶变换红外（FTIR）光谱分析，发现了具有木栓质特征的显著吸收带。然而，在针叶的凯氏带中，FTIR光谱很少检测到木栓质的证据。用质外体示踪剂钙黄绿素和黄连素探测针叶和根中凯氏带的质外体通透性。根中的凯氏带有效地阻断了钙黄绿素和黄连素的质外体运输（AT）。针叶中的凯氏带阻断了钙黄绿素的AT，但黄连素的扩散未受抑制，且在针叶的维管组织中可检测到硫氰酸黄连素晶体。根据所提供的数据，必须得出结论，与根中的凯氏带相比，以缺乏木栓质为特征的针叶中的凯氏带溶质通透性更高。
