Pb在类芦组织和亚细胞中的分布规律和毒害效应

通过研究类芦体内Pb在组织和亚细胞水平的毒害效应和分布规律,分析类芦对Pb的耐性机制,为了解类芦对重金属的富集能力、耐性机制及逆境生理提供理论依据。采用营养液培养的方法,以Pb为目标污染物,胁迫后测定类芦体内(分为根和叶)Pb在各亚细胞组分的含量,并分别通过扫描电子显微镜(SEM)和能谱透射电子显微镜(TEM-EDS)观察Pb在组织和亚细胞的分布以及对其损伤情况。结果显示:从组织水平来看,Pb胁迫下组织结构由排列整齐变为不规则,局部出现较大破损而形成一些碎片,并出现晶体堵塞导管的现象;从亚细胞水平来看,类芦根叶细胞均损伤,出现细胞壁模糊、线粒体减少、叶绿体肿胀等现象,在根部Pb主要分布于细胞壁(12.28 mg·kg~(-1))和以液泡为主的可溶组分(38.82 mg·kg~(-1)),而叶片中以可溶组分占比例最大(32.56%),且EDS元素分析也显示细胞内含有大量Pb。这些结果表明,类芦对Pb有一定的吸收富集能力,并可通过改变Pb在其组织和亚细胞水平的分布来降低毒害作用,因此类芦对重金属Pb有较强的耐性。

The distribution and toxic effects of Pb at the levels of the tissue and sub-cellular in Neyraudia reynaudiana

In order to examine the phytoremediation potential of Neyraudia reynaudiana,the study explored the toxic effects and distribution of lead(Pb) at the levels of the tissue and sub-cellular in this species and analyzed the supplementing the growth medium with Pb as a target pollutant. After cultivation was concluded,the uptake of sub-cellular Pb was determined,and the distribution of Pb as well as the Pb-induced damage was respectively assessed through scanning electron microscope(SEM) and transmission electron microscope with energy dispersive X-ray spectroscopy(TEM-EDS). Pb caused the tissues to become irregular and fragmented by injuries;additionally,a portion of the catheters were filled with crystals.At the sub-cellular level,many phenomena demonstrated that leaf and root cells were harmed;for example,cell walls became vague,mitochondria were less numerous,and chloroplasts were swollen. Pb was mainly distributed in the cell wall(12.28 mg·kg^-1) and the vacuole(38.82 mg·kg^-1) of root cells,and it accounted for 32.56% of the total biomass in the leaves.In addition, the EDS analysis found a significant amount of Pb in cells.These results suggest that N.reynaudiana has a strong ability to both absorb and tolerate Pb. Moreover,the species may alter the distribution of Pb at both the tissue and the sub-cellular levels to reduce toxicity.Therefore,N.reynaudiana is well suited for phytoremediation in Southern China and elsewhere.