Talbot Mark J, Wasteneys Geoffrey, McCurdy David W, Offler Christina E
School of Environmental and Life Sciences, The University of Newcastle, Newcastle, NSW 2308, Australia.
Plant Cell Biology Group, Research School of Biological Sciences, The Australian National University, Canberra, ACT 2601, Australia.
Funct Plant Biol. 2007 May;34(4):307-313. doi: 10.1071/FP06273.
The arrangement of cellulose microfibrils and cortical microtubules in transfer cells depositing flange wall ingrowths have been determined with field emission scanning electron microscopy and immunofluorescence confocal microscopy. In xylem transfer cells of wheat (Triticum aestivum) stem nodes and transfer cells of corn (Zea mays) endosperm tissue, cellulose microfibrils were aligned in parallel bundles to form the linear wall ingrowths characteristic of flange ingrowth morphology. In both cell types, linear bundles of cellulose microfibrils were deposited over an underlying wall composed of randomly arranged microfibrils. Acid extraction of wheat xylem transfer cells established that flange ingrowths were composed of crystalline cellulose. Immunofluorescence labelling of microtubules in wheat xylem transfer cells showed that bundles of microtubules were positioned directly below and parallel with developing flange ingrowths, whereas more mature ingrowths were flanked by bundles of microtubules. These results show that the parallel organisation of cellulose microfibrils in flange wall ingrowths is similar to those in secondary wall thickenings in xylem elements, and that deposition of these structures in transfer cells is also likely to involve bundling of parallel arrays of microtubules. Our observations are discussed in terms of the possible role of microtubules in building flange-type wall ingrowths and the consequences in terms of predicted mechanisms required to build the fundamentally different reticulate-type wall ingrowths.
利用场发射扫描电子显微镜和免疫荧光共聚焦显微镜确定了在沉积凸缘壁内突的传递细胞中纤维素微纤丝和皮层微管的排列。在小麦（Triticum aestivum）茎节的木质部传递细胞和玉米（Zea mays）胚乳组织的传递细胞中，纤维素微纤丝排列成平行束，形成凸缘内突形态特有的线性壁内突。在这两种细胞类型中，纤维素微纤丝的线性束沉积在由随机排列的微纤丝组成的下层壁上。对小麦木质部传递细胞进行酸提取表明，凸缘内突由结晶纤维素组成。对小麦木质部传递细胞中的微管进行免疫荧光标记显示，微管束直接位于正在发育的凸缘内突下方并与之平行，而更成熟的内突则由微管束位于其两侧。这些结果表明，凸缘壁内突中纤维素微纤丝的平行组织与木质部细胞次生壁加厚中的情况相似，并且这些结构在传递细胞中的沉积也可能涉及微管平行阵列的成束。我们从微管在构建凸缘型壁内突中的可能作用以及构建根本不同的网状型壁内突所需的预测机制方面对我们的观察结果进行了讨论。
