RADIAL MOVEMENT OF CATIONS ACROSS AERENCHYMATOUS ROOTS OF ZEA-MAYS MEASURED BY ELECTRON-PROBE X-RAY-MICROANALYSIS
RADIAL MOVEMENT OF CATIONS ACROSS AERENCHYMATOUS ROOTS OF ZEA-MAYS MEASURED BY ELECTRON-PROBE X-RAY-MICROANALYSIS
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DOI：
10.1093/jxb/37.6.823
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发表时间：
1986-06-01
影响因子：
6.9
通讯作者：
FOURCY, A
中科院分区：
文献类型：
--
作者：
DREW, MC;FOURCY, A
Rb+ 和 Sr2+（作为 K+ 和 Ca2+ 的类似物）的径向运动，通过电子探针 X 射线微量分析对玉米（Zea mays L. cv. LG 11）的通气根进行。目的是确定当大部分根皮层在形成过程中发生退化和溶解以及通气根中大量充满气体的空间时，离子到达木质部的可能途径。从含有 K+ 和 Ca2+ 的全浓度营养液中吸收 Rb+ 和 Sr2+ 1、6 和 24 小时后，检查这些元素的分布。通过低温切片和冻干制备的横根切片用于电子探针 X 射线微量分析。如果充满气体的空间内衬的细胞壁变得木木化（如早期文献中报道的），这种发展可能会阻碍离子运动，但我们发现 Rb+ 或 Sr2+ 可以像在完整皮质细胞的壁中一样容易地在皮质细胞裂解后剩余的径向壁残留物中迁移。然而，Rb+ 和 Sr2+ 的分布不同。整个根部铷+缺乏浓度梯度与其主要在共质体中的运输相一致，共质体由偶尔排列的完整皮质细胞构成，桥接充满气体的空间。 Sr2+ 明显的浓度梯度是由于其通过由完整细胞壁和裂解细胞壁构成的质外体途径移动至内皮层。
The radial movements of Rb+ and Sr2+, as analogues for K+ and Ca2+, were followed by electron probe X-ray microanalysis in aerenchymatous roots of maize (Zea mays L. cv. LG 11). The object was to determine the possible pathways by which ions can reach the xylem when degeneration and lysis of much of the root cortex has taken place during formation and numerous gas-filled spaces in aerenchymatous roots. After 1, 6 and 24 h uptake of Rb+ and Sr2+ from a full strength nutrient solution containing K+ and Ca2+, the distribution of these elements was examined. Transverse root sections, prepared by cryostat sectioning and lyophilization, were used for electron probe X-ray microanalysis. If the cell walls lining gas-filled spaces become suberized (as reported in earlier literature), this development might be expected to retard ion movement, but we found that Rb+ or Sr2+ could migrate as readily in the radial wall residues remaining after cortical cell lysis, as in the walls of intact cortical cells. The distributions of Rb+ and Sr2+ differed, however. The lack of a concentration gradient for Rb+ across the root was compatible with its transport mainly in the symplast, constituted by occasional files of intact cortical cells bridging the gas-filled spaces. The evident concentration gradient for Sr2+ was accounted for by its movement to the endodermis by the apoplastic pathway constituted by the walls of intact and lysed cells.