茶多酚和钙离子添加对茶树叶片铅吸收和亚细胞分布的影响

Effects of tea polyphenols and calcium ions on absorption and subcellular distribution of lead in tea leaves

为研究铅胁迫下添加茶多酚和钙离子对茶树叶片铅吸收和亚细胞分布的影响,通过水培试验,结合差速离心法和扫描透射电镜技术研究舒茶早茶树叶片铅吸收特性及铅的亚细胞分布,并比较茶多酚和钙离子两种不同添加剂对茶树叶片铅吸收和亚细胞分布影响的差异。结果表明:铅胁迫显著增加茶树叶片中铅的含量,显著降低钙的含量。茶多酚添加后,茶树叶片铅含量显著降低30.89%,钙含量显著增加11.10%;添加钙离子对茶树叶片铅含量无显著影响,但使钙的含量显著增加了34.57%。铅被茶树吸收后,茶树叶片表面和气孔周围褶皱度增加,铅沉积于液泡内,造成细胞器的损伤;茶多酚和钙离子的添加减轻了铅对叶片细胞的损害程度。铅在茶树叶片亚细胞组分中的分布顺序依次是细胞壁、细胞质和液泡、质体和叶绿体、线粒体。研究表明,茶多酚主要通过减少铅的吸收量来缓解茶树叶片的铅毒害作用,钙离子主要通过改变铅在茶树叶片细胞不同组分中的含量(增加细胞壁对铅的截留、降低细胞内铅的含量)来缓解重金属铅对茶树叶片细胞的伤害。

Hydroponic experiments combined with differential centrifugation and electron microscopy were used to study the characteristics and subcellular distribution of lead absorption in Shuchazao tea leaves under lead stress.Differences in the absorption and subcellular distribution of lead in tea leaves were compared after tea polyphenol and calcium ion addition.Lead stress significantly increased the lead content and decreased the calcium content in tea leaves.After the addition of tea polyphenols,the lead content in tea leaves decreased significantly and the calcium content increased significantly;the reduction rate of lead and increase rate of calcium were 30.89% and 11.10%,respectively.The addition of calcium ions had no significant effect on the lead content in tea leaves,but significantly increased the calcium content under lead stress,with an increase rate of 34.57%.The absorption of lead by tea plants increased the folds on the surface of leaves and around stomata,and lead was deposited in vacuoles,causing damage to organelles.The addition of tea polyphenols and calcium ions reduced cell damage due to lead stress.The distribution order of lead in the subcellular components of tea leaves was cell wall,cytoplasm and vacuole,plastid and chloroplast,and mitochondria.Tea polyphenols primarily alleviate the lead toxicity of tea leaves by reducing lead absorption,and calcium ions alleviate the toxic effect of lead on tea leaf cells by altering the lead content in different components of tea leaf cells(increasing the interception of lead by the cell wall and reducing the lead content in cells).