空气重金属元素在悬铃木叶中的亚细胞分布及其区隔化效应

Subcellular Distribution and Compartmentalization Effects of Heavy Metal Elements from Atmosphere in Platanus hispanica

以南京市常见行道树二球悬铃木为试材,研究了交通繁忙区和相对清洁区道路两边悬铃木叶内6种重金属元素的亚细胞分布及其区隔化效应.结果显示:交通污染区悬铃木叶内各亚细胞组分中Cr、Cu、Ni、Pb和Zn 5种重金属元素的含量均明显高于对照区,交通空气污染是影响其含量增加的主要原因之一.相对清洁区和交通污染区5种重金属元素在悬铃木叶片、叶柄的细胞壁组分中含量最高,胞外隔离系数和污染指数均大于0.900,细胞壁是大气重金属元素重要的吸滞器官,并对重金属有明显的阻隔效应;胞内细胞器对Pb和Cu的隔离系数和污染指数最大,细胞器双层膜能在一定程度上抵御重金属元素进入细胞内.悬铃木叶片和叶柄亚细胞组分的污染指数表现为胞质组分>细胞壁组分>细胞器组分,即包括液泡液在内的胞质组分是囤积重金属元素的场所.研究表明,悬铃木叶片、叶柄各亚细胞组分对重金属均有不同程度的累积能力,叶内胞质组分的囤积作用以及细胞壁、质膜与细胞器双层膜的区隔化作用可能是悬铃木叶解除重金属元素毒害的重要原因.

Common street trees Platanus hispanica in Nanjing were used to study subcellular distribution and compartmentalization effects of six heavy metal elements（Pb,Cd,Cr,Cu,Ni and Zn） in its＇ leaves on both sides of the road in the heavy traffic areas and the relatively clean area.The results showed that：The contents of 5 heavy metal elements（except Cd） in the heavy traffic areas were significantly greater than that in the relatively clean areas,which means transportation pollution was one of the major causes in increasing heavy metal element contents.5 elements accumulation（except Cd） in cell wall fractions of leaves and petioles were the highest the heavy traffic areas,and extracellular segregation coefficient and the pollution index was greater than 0.900.Therefore this indicates that cell wall is an important organ to absorb heavy metal elements from the atmosphere,which means its barrier is really exist.The segregation coefficient of intracellular organelles and the pollution index for Pb and Cu were the largest,and indicated that double membrane of organelles in plant cells against heavy metals into the cells.In addition,the pollution index of subcellular fractionsin in leaves and petioles of P.hispanica showed as follows：cytoplasmi supernatant fractioncell wall componentscell organelle fractions,and indicated that cytoplasmi supernatant fraction including vacuoles liquid is accumulation place of heavy metal elements in cell.The results showed leaves and petioles of P.hispanica could absorb heavy metal pollutants to different extent depending on heavy metal kinds and subcellular fraction.Therefore heavy metal elements accumulated in cytoplasmi supernatant fraction and compartmentalization of the cell wall.Plasma membrane and double membrane of organelles in cells may be intricately linked with 5 elements detoxification in P.hispanica.