铬(Cr6+)对水花生愈伤组织的毒害效应

摘要

研究了不同浓度的Cr6+(0、0.1、0.2、0.5、1.5 mmolL-1)对水花生愈伤组织内几种代表性生理生化指标的胁迫效应,并对其进行电镜观察.结果表明:(1)随着Cr6+浓度的增加,总叶绿素、叶绿素a/b和可溶性蛋白含量,均呈先升后降趋势.(2)超氧阴离子(O 2)和过氧化氢(H2O2)含量在0.1 mmolL-1时应激性地增加,随后又呈先降后升趋势,但始终高于对照.(3)可溶性糖含量随Cr6+浓度的升高逐渐升高.(4)超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性以及抗坏血酸(ASA)和谷胱甘肽(GSH)含量均表现先升后降.(5)电镜观察发现,Cr6+使叶绿体类囊体片层扭曲,被膜破损,有巨大淀粉粒存在;线粒体嵴突数目减少,空泡化;核仁松散、消失,染色质凝集;内质网以形成囊泡形式逐渐消失.可见,Cr6+胁迫破坏了水花生愈伤组织的正常生理生化活动,对其细胞超微结构造成了不可逆的损伤.%This study focused on changes of several representative physiological characteristics and ultrastructure in the callus of Alternanthera philoxreroides under different concentrations of Cr6+ stress(0,0. 1,0. 2,0. 5,1.5 mmol ·L -1 ). The results showed that with the increasing of Cr6 +, (1) total chlorophyll (Chl), chlorophyll a/b ( Chl a/b) and total soluble protein contents showed the same trend,which increased firstly and then decreased. (2)Superoxide anion ( O2- · ) and hydrogen peroxide ( H2 O2 ) content irritably increased compared to the control group, then decreased, however, it's always higher than that of control. (3)The soluble sugar content enhanced with the increasing of Cr6 + concentration. (4) Activities of supeoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) and ASA and GSH contents all increased first and then decreased. (5)Transmission electron microscope observation indicated that Cr6+ also imposed injury action on ultrastructure of callus cells., thylakoid twisted, chloroplast enyelope broke and large starch grain formed,mitochondria disappeared and formed vacuolization, nucleolus lost and chromatin condensed in nucleus,and endoplasmic reticulum vanished by means of vesiculation. The conclusion could be reached that toxic effects of Cr6+ on callus resulted in disorder of physiological and biochemical metabolism and destruction of ultrastructure of callus cells.