DEVELOPMENT OF THE ENDODERMIS AND PHI LAYER OF APPLE ROOTS
DEVELOPMENT OF THE ENDODERMIS AND PHI LAYER OF APPLE ROOTS
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DOI：
10.1007/bf01276298
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发表时间：
1979-01-01
期刊：
影响因子：
2.9
通讯作者：
MACKENZIE, KAD
中科院分区：
文献类型：
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作者：
MACKENZIE, KAD
内胚层细胞中的木栓质薄片和三级纤维素壁比一年生根更靠近根尖。Casparian条带和木质化增厚分别在离根尖4-5 mm的所有内胚层和phi层细胞的背斜壁上分化。木栓质片位于离根尖16mm的细胞壁内表面，仅位于韧皮部两极对面的内胚层。接着是离根尖35毫米的另一层纤维素层。与最后的发育相一致的是，木质素层和纤维素层从外切向壁和细胞质碎片上分离。木质部极内胚层（占内胚层的50%）在离根尖85mm处发育相似，但不塌陷。在距根尖100 ~ 150mm处，根的表面颜色由白色变为棕色，中柱鞘开始形成木栓，皮层开始剥落。在这个阶段可以看到一些次生木质部分子。胞间连丝穿过内胚层的粗蛋白层和纤维素层，但与内胚层相比，胞间连丝在皮层的外切向壁和径向壁出现的频率更高，这表明该层可能调节流入柱的水和营养物质。
Suberin lamellae and a tertiary cellulose wall in endodermal cells are deposited much closer to the tip of apple roots than of annual roots. Casparian strips and lignified thickenings differentiate in the anticlinal walls of all endodermal and phi layer cells, respectively, 4-5 mm from the root tip. Suberin lamellae are laid down on the inner surface of the cell walls 16 mm from the root tip and only in the endodermis opposite the phloem poles. This is followed by an additional cellulosic layer 35 mm from the root tip. Coincidentally with this last development, the suberin and cellulose layers detach from the outer tangential walls and the cytoplasm fragments. The xylem pole endodermis (50% of the endodermis) develops similarly at a distance of 85 mm from the root tip, but does not collapse. At a distance of 100-150 mm from the root tip, the surface color of the root changes from white to brown, a phellogen develops from the pericycle and sloughing of the cortex begins. A few secondary xylem elements are visible at this stage. Plasmodesmata traverse the suberin and cellulose layers of the endodermis, but their greater frequency in the outer tangential and radial walls of the phi layer when compared with the endodermis suggests that this layer may regulate the inflow of water and nutrients to the stele.