Figueroa Julio Alberto Landero, Wrobel Katarzyna, Afton Scott, Caruso Joseph A, Corona Felix Gutierrez J, Wrobel Kazimierz
Instituto de Investigaciones Cientificas, Universidad de Guanajuato, L. de Retana No. 5, 36000 Guanajuato, Mexico.
Chemosphere. 2008 Feb;70(11):2084-91. doi: 10.1016/j.chemosphere.2007.08.066. Epub 2007 Oct 10.
Phytochelatins (PCs) were determined in the wild plants, focusing on their relationship with the levels of heavy metals and humic substances (HS) in soil. Ricinus communis and Tithonia diversifolia were collected from several sites in Guanajuato city (Mexico), which had long been the silver and gold mining center. The analysis of PCs in root extracts was carried out by liquid chromatography (derivatization with monobromobimane). Total Ag, Cd, Cu and Pb in plant roots and in soil samples, as well as soil HS were determined. The association of metals with HS in soils was evaluated by size exclusion chromatography (SEC) with UV and ICP-MS detection. The results obtained revealed the induction of PCs in R. communis but not in T. diversifolia. The levels of Cd and Pb in plant roots presented strong positive correlation with PC-2 (r=0.9395, p=0.005; r=0.9573, p=0.003, respectively), indicating that these two metals promote PCs induction in R. communis. On the other hand, the inverse correlation was found between soil HS and metal levels in roots of R. communis (Cu>Pb>Cd>Ag), in agreement with the decreasing affinity of these metals to HS. Importantly, the inverse correlation between soil HS and plant PC-2 was observed (r=-0.7825, p=0.066). These results suggest that metals strongly bound to HS could be less bioavailable to plants, which in turn would limit their role in the induction of PCs. Indeed, the SEC elution profiles showed Pb but not Cd association with HS and the correlation between metal in soil and PC-2 in plant was statistically significant only for Cd (r=0.7857, p=0.064). Based on these results it is proposed that the role of heavy metals in PCs induction would depend on their uptake by R. communis, which apparently is controlled by the association of metals with soil HS. This work provides further evidence on the role of environmental conditions in the accumulation of heavy metals and phytochelatin production in plants.
对野生植物中的植物螯合肽（PCs）进行了测定，重点关注其与土壤中重金属和腐殖质（HS）含量的关系。从墨西哥瓜纳华托市的几个地点采集了蓖麻和肿柄菊，该市长期以来一直是银和金的开采中心。通过液相色谱法（用单溴代联苯胺衍生化）对根提取物中的PCs进行分析。测定了植物根和土壤样品中的总银、镉、铜和铅以及土壤HS。通过尺寸排阻色谱法（SEC）结合紫外和电感耦合等离子体质谱检测来评估土壤中金属与HS的结合情况。所得结果表明蓖麻中诱导产生了PCs，而肿柄菊中未诱导产生。植物根中镉和铅的含量与PC-2呈强正相关（r分别为0.9395，p = 0.005；r为0.9573，p = 0.003），表明这两种金属促进了蓖麻中PCs的诱导。另一方面，在蓖麻根中发现土壤HS与金属含量呈负相关（铜>铅>镉>银），这与这些金属对HS的亲和力降低一致。重要的是，观察到土壤HS与植物PC-2呈负相关（r = -0.7825，p = 0.066）。这些结果表明，与HS强烈结合的金属对植物的生物有效性可能较低，这反过来会限制它们在诱导PCs中的作用。实际上，SEC洗脱曲线显示铅与HS结合而镉未与HS结合，并且土壤中的金属与植物中的PC-2之间的相关性仅对镉具有统计学意义（r = 0.7857，p = 0.
