铅在茶树体内的分布及化学形态特征

Characteristic of distribution and chemical forms of Pb in tea plant varieties

采用水培试验,结合亚细胞组分分离和化学形态提取技术,研究了茶树品种龙井43和迎霜不同器官的Pb含量,及其在根系亚细胞中的分布和化学结合形态.结果表明:在Pb胁迫下,两个品种茶树根系的形态特征不同;龙井43新叶中Pb含量随营养液Pb浓度的提高显著增加,而迎霜的变化不显著.两个品种茶树根系亚细胞中Pb的含量分布及结合形态均存在差异,低浓度Pb处理下,龙井43根亚细胞组分(除可溶物质外)中Pb含量均低于迎霜;而高浓度Pb处理下,龙井43根亚细胞组分(除细胞壁外)中Pb含量均高于迎霜;龙井43根中醋酸(HAc)提取态的Pb含量比例最高,其他化学形态的高低顺序为NaCl提取态>HCl提取态/H2O提取态>乙醇提取态;而迎霜根中NaCl提取态Pb成分比例最高,其他化学形态的高低顺序为HAc提取态>HCl提取态/H2O提取态>乙醇提取态.迎霜对Pb毒害的耐受能力强于龙井43.

A hydroponics experiment combined with subcellular fractionation and sequential extraction was conducted to study the Pb concentration in different organs of two tea plant varieties（Longjing 43 and Yingshuang） and the Pb subcellular distribution and chemical forms in the roots of the varieties.Under Pb stress,the root system of the two varieties had different features in morphology.With the increasing concentration of Pb in culture solution,the Pb concentration in Longjing 43 young leaves increased,but that in Yingshuang＇s had no significant variation.A marked difference was observed in the Pb subcellular distribution and its chemical forms in roots between the two varieties under Pb stress.In Longjing 43 roots,all subcellular fractions except soluble ones had a lower Pb concentration at low Pb stress,and all the subcellular fractions except cell wall ones had a higher Pb concentration at higher Pb stress,compared with those in Yingshuang＇s.In Longjing 43 roots,the HAc-extractable Pb occupied the greatest proportion,followed by NaCl-extractable Pb,HCl-and H2O-extractable Pb,and ethanol-extractable Pb;while in Yingshuang＇s,NaCl-extractable Pb had the greatest proportion,followed by HAc-extractable Pb,HCl-and H2O-extractable Pb,and ethanol-extractable Pb.Based on these findings,tea plant variety Yingshuang was likely to possess a higher tolerance to Pb than Longjing 43 did.