铝胁迫下大豆根尖细胞铝的微区分布与耐铝性分析

以浙春3号为实验材料, 利用透射电镜(TEM: Transmission Electron Microscope)-X-射线能谱(EDS: Energy Dispersive X-ray), 调查铝胁迫下大豆根尖铝的微区分布及耐铝性。结果表明，Al³⁺胁迫导致根尖细胞细胞壁不规则加厚, 线粒体数量增多, 核膜膨胀, 液泡中存在较多的电子致密沉淀物。90 mg L^-1 Al³⁺处理的根尖细胞内含物完全降解消失, 仅剩细胞壁。10 mg L^-1 Al³⁺处理的线粒体、细胞壁和液泡电子致密沉淀物中均检测到Al；随着Al³⁺处理浓度的增大, 各细胞器中Al的质量和原子数百分比逐渐增大。线粒体在60 和90 mg L^-1Al³⁺处理下, 液泡电子致密沉淀物在90 mg L^-1Al³⁺处理下，均未被检测出Al。在60 mg L^-1Al³⁺处理下唯一一次在细胞核中检测到Al。Al³⁺抑制了根系生长, 根系细胞中细胞壁的Al³⁺含量受影响最明显。P/Al在细胞壁和线粒体中的相对原子数随Al³⁺浓度的增大而下降。研究结果表明X–射线能谱对铝在亚显微结构上的定位是一种快速、有效的方法。铝最先积累在细胞壁上, 随Al³⁺处理浓度增大逐渐积累于部分细胞器和细胞核中, 且含量在细胞中的分布亦由外向里呈递减趁势。

Distribution of Al3+ in Subcellular Structure of Root Tips Cells and Aluminum Tolerance in Soybean

Aluminum(Al) toxicity is a major limiting factor for yield and quality in crop production in acid soil. Micromolar concentrations of Al³⁺ may inhibit root elongation and consequently influence water and nutrient uptake, resulting in poor plant growth. The microanalysis of the elements was conducted on Zhechun 3 by using Transmission Electron Microscope (TEM) and Energy Dispersive X-ray (EDS) to examine the distribution of Al³⁺ in root tips and Al resistance of soybean. We found that Al³⁺ stresses resulted in irregularly thickened cell wall, increased number of mitochondria, expanded nuclear membrane, and densified precipitates of vacuole. Under the highest Al³⁺ concentration, the mitochondria and other organelles disappeared but cell wall. We detected Al in cell wall, mitochondria and electron-dense precipitates of vacuole of root tip cell under the 10 mg L^-1Al³⁺ stresses by EDS. With the increase of external Al³⁺ concentration treated, the weight and atomic percentage of Al in the organelles increased. The Al³⁺ was found in nuclei when the external Al³⁺ was over 60 mg L^-1. And there was no Al³⁺ in mitochondrion under 60 mg L^-1 and 90 mg L^-1Al³⁺ treatments and electron-dense precipitates of vacuole under the 90 mg L^-1 Al³⁺ stresses. The 14 days Al³⁺ stresses significantly inhibited the growth of root system. The content of Al³⁺ in cell wall was most significantly impacted by the external Al³⁺ concentration. The atomic number of P / Al in cell wall and mitochondria decreased with increased Al³⁺ content. EDS can be used to determine the subcellular location of Al³⁺. As the treatment concentrations of Al³⁺ increased, Al³⁺ primarily accumulated in the cell wall, gradually gathered in part of the organelles and nuclei. The Al³⁺ concentrations also decreased from out layer to insider in the cell.