Chemosphere：不同根区及根毛长度在高/非高积累生态型东南景天中的镉吸收特征 | NMT植物重金属创新科研平台

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2020/06/15 15:17

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研究使用平台：NMT植物重金属创新科研平台

期刊：Chemosphere

主题：不同根区及根毛长度在高/非高积累生态型东南景天中的镉吸收特征

标题：Cd-induced difference in root characteristics along root apex contributes to variation in Cd uptake and accumulation between two contrasting ecotypes of Sedum alfredii

影响因子：5.108

检测指标：Cd2+流速

检测样品：东南景天

Cd2+流实验处理方法：

不同生态型东南景天在0 或25μM Cd(NO3)2处理7天

Cd2+流实验测试液成份：

0.025mM CdCl2，0.1mM KCl，pH5.8

作者：四川农业大学王昌全、陶琦；浙江大学李廷强

中文摘要（谷歌机翻）

根尖是水分和离子吸收最活跃的部分，但是，人们对根部特征的沿根尖的纵向变化以及金属在高蓄积物中吸收的后果知之甚少。

在这里，我们比较了镉（Cd）引起的两种生态型东南景天草根尖的纵向变化，并评估了它们对Cd吸收的影响。在镉处理下，随着时间的推移，非高蓄积生态型（NHE）的细胞死亡开始从表皮到石碑，死细胞数量明显高于高蓄积生态型（HE）。Cd诱导NHE根尖周围的边界样细胞（BLC）的存在阻止了Cd进入根，但是在HE根尖几乎没有观察到BLC。

此外，与HE相比，Cd处理的NHE在分生区和伸长区的比例分别降低了76％和52％，导致这些区的Cd流入量减少，Cd荧光强度降低。在分化区，与HE相比，Cd诱导NHE的根毛（RHs）更早开始，RHs密度更低，RHs长度更短，RHs半径更厚，并且单核细胞少。与HE相比，这些显着的变化导致NHE RH中的Cd流入量减少，Cd荧光强度降低。

此外，暴露于Cd下的细胞壁厚度下降导致HE细胞壁中较少的细胞壁键合Cd。因此，Cd诱导的根部特征以及根尖的改变导致了两种生态型苜蓿链球菌对Cd吸收和积累的差异

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Figure 6. Cd2+ influx andlocalization in different root zones along root apex of hyperaccumulatingecotype (HE) and non-hyperaccumulating ecotype (NHE) of Sedumalfredii.Two ecotypes were cultivated in a nutrient solution containing 0 or 25 μM Cd(NO3)2 (Cd0, Cd 25) for 7d. (A) the Cd localization in root apex was visualized by fluorescence ofLeadmiumTM Green AM dye in HEand NHE. FL, fluorescence 591 images; BF, brightfield images. Bars, 100 mm. (B) net Cd2+ influx in root cap (r zone), meristematic zone (m zone)and elongation zone (e zone) of HE and NHE. (C) the Cd localization in roothairs within different distance from root tip was visualized by fluorescence ofLeadmiumTM Green AM dye in HEexposed to 25 μM Cd(NO3)2. (D) net Cd2+ influx in root hairs within different distance from roottip of HE and NHE. (E) correlation between root hair length and net Cd2+ influx in roothairs of HE and NHE. Error bars represent means ± SE (n = 15). * indicatessignificant differences between ecotypes at P<0.05 (Student’s t-test).

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英文摘要

The root apex is the most active part for water and ions uptake, however, longitudinal alterations in root characteristics along root apex and consequences for metal uptake in hyperaccumulator are poorly understood.

Here, we compared cadmium (Cd)-induced longitudinal alterations in root apex of two ecotypes of Sedum alfredii and assess their effects on Cd uptake. Under Cd treatment, cell death began from epidermis to the stele in non-hyperaccumulating ecotype (NHE) over time, and the number of dead cells was significantly higher than that in hyperaccumulating ecotype (HE). Cd-induced the presence of border-like cells (BLCs) surrounding the root tip of NHE prevented Cd from entering roots, however, almost no BLCs were observed in the root tip of in HE.

Besides, Cd-treated NHE exhibited 76% and 52% decrease in the proportions of meristematic and elongation zone, respectively, resulting in lower Cd influx and less intensive Cd-fluorescence in these zones, as compared with HE. In the differentiation zone, Cd induced earlier initiation of root hairs (RHs), lower RHs-density, shorter RHs-length, thicker RHs-radius and less trichoblasts in NHE than those in HE. These remarkable variations led to less Cd influx and lower intensity of Cd-fluorescence in RHs of NHE than those of HE.

Furthermore, decline in cell wall thickness under Cd exposure resulted in less cell-wall-bond Cd in the cell wall of HE. Therefore, Cd-induced alterations in root characteristics alongside root apex contributed to the difference in Cd uptake and accumulation between two ecotypes of S. alfredii.