摘要
设置不同的Al3+浓度(0、25、50、100、200、400μmol.L-1)和培养时间(12、24h),研究了边缘细胞活性和大豆(Glycine max)根中过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)随Al3+浓度及处理时间变化的规律,并通过Hoechst33342-PI双重荧光染色、梯状DNA(即DNA ladder)分析和末端脱氧核糖核酸转移酶介导的dUTP切口末端标记(即TUNEL原位标记)检测,研究了Al3+对大豆根边缘细胞程序性死亡诱导的生理生态作用。结果表明,Al3+胁迫能诱导边缘细胞的死亡,随着Al3+浓度的升高和处理时间的延长,细胞死亡率增加。通过Hoechst33342-PI双重荧光染色、DNA ladder分析和TUNEL原位标记,检测到Al3+胁迫下发生程序性死亡的边缘细胞。其表现为:在400μmol·L-1Al3+诱导大豆根24h时,核酸电泳显示细胞DNA发生特异性降解并形成阶梯状电泳条带(DNAladder),用TUNEL原位标记检测200和400μmol·L-1Al3+处理12h后的大豆根边缘细胞,发现DNA的3′-OH端被原位特异标记,二氨基联苯胺(DAB)显色后,细胞核为阳性或强阳性。同时,高浓度Al3+(>100μmol·L-1)处理下,CAT、POD和SOD活性均有不同程度的下降,CAT和SOD的活性也随处理时间的延长而降低。说明在Al3+胁迫下边缘细胞的死亡可能是一种程序性死亡形式,高浓度Al3+胁迫下,通过诱导活性氧在细胞体内的产生和累积而导致细胞凋亡,此过程是其对逆境胁迫所作出的生理生态防御性应答方式之一。
Aims Programmed cell death （PCD） plays an important role in plant growth and development, which correlates with adaptation of the plant to environment stress. Root border cells have many important biological functions in protecting the plant root tip from biotic and abiotic stress, which is a popular research topic recently. However, few studies have focused on PCD of root border ceils and the phytoecological effect of aluminum on it. Our objective was to study the phytoecological and molecular ecological mechanism of root border cells in resisting aluminum （Al） toxicity.
Methods We investigated change in viability of border ceils, activities of catalase （CAT）, peroxidase （POD） and superoxide dismutase （SOD）, and PCD of root border cells by Al^3＋ induced in soybean （ Glycine max） root tips with different Al^3＋ concentrations （0, 25, 50, 100, 200 and 400 μmol·L^-1 Al^3＋ ） and treatment times （ 12 and 24 h）. PCD was observed through Hoechst33342-PI fluorescent staining, DNA ladder and TdT-mediated dUTP nick end labeling （TUNEL） analysis. Important findings Aluminum can induce the death of root border cells. The viability of border cells decreases with increased Al^3＋ concentration and treatment time. The progressive delineation of fragmented DNA was coincident with the appearance of DNA ladder after being exposed to 400 μmol·L^-1 Al^3＋ for 24 h. TUNEL analysis of border cells revealed that the nuclear DNA strand breaks can be identified by labeling free 3＇-OH termini after treatment with 200 and 400 μmol·L^-1 Al^3＋ for 12 h. Diaminobenzidine （DBA） staining indicated that the nucleus was positive and strong positive. Otherwise, CAT and SOD activities declined with increasing Al^3＋ concentration and treatment time under higher Al^3＋ concentration （ 〉 100μmol· L^- 1）, and we observed no significant differences in POD activity among different Al^3＋ concentrations and treatment times. These results indicated that border cell death may be a PCD under Al^3＋ stress. High Al^3＋ concentration induced PCD through enhancing reactive oxygen species （ROS）, which is one of the ways of resisting adversity in plants.
出处
《植物生态学报》
CAS
CSCD
北大核心
2008年第3期690-697,共8页
Chinese Journal of Plant Ecology
基金
国家自然科学基金(30540056)
浙江省自然科学基金(304185、303461和504135)
关键词
铝毒
大豆
边缘细胞
细胞程序性死亡
抗氧化酶
生理生态
aluminum toxicity, soybean, border cells （BC）, programmed cell death （PCD）, antioxidase, phytoecology
