铅持续胁迫下不同世代蚕豆生理生化指标的变化

摘要

为了解长期持续铅胁迫下植物不同世代间生理生化指标的变化,分析植物对铅污染的适应机制及植物对长期持续污染的响应机理,该研究以在250 mg·kg-1Pb持续污染的实验田中种植所得的第4、第8、第10、第13和第15世代蚕豆种子为材料,通过盆栽法,与同世代未受Pb胁迫的蚕豆做对照,分析了与抗氧化酶系统、总代谢等相关的8个生理指标,即叶绿素、蛋白质、可溶性糖、脯氨酸(PRO) 、丙二醛(MDA)含量及超氧化物歧化酶(SOD) 、谷胱甘肽还原酶(GR)和苹果酸脱氢酶(MDH)活力.结果表明:(1)在长期持续Pb胁迫下,与蚕豆光合作用能力有关的叶绿素含量在第8代与第13代之间与对照组相比具有显著的差异性(P＜0.05).(2)可溶性糖含量随胁迫时间的延长而逐渐升高,并在第10代时达到最高,随后开始向无污染的正常水平恢复并趋于稳定;蛋白质含量在胁迫至第13代后开始增加.(3) MDA与PRO含量在胁迫至第10代时达到最高,并随胁迫时间的延长而降低,至第13 代后逐渐趋于稳定.(4)抗氧化酶系统中的SOD、GR和MDH也同样呈现出先高后低的趋势,且GR的变化程度最大,MDH活力最早表现出与对照组的最大差异.研究认为:在长期的持续Pb污染胁迫下,蚕豆种群对Pb污染胁迫的适应性不断提高.%In order to understand the change of physiological and biochemical indexes of plants exposed under long-termed continuous heavy metal Pb stress,and to obtain the adaptive mechanism of plants in long-termed heavy metal polluted envi-ronment,we selected the fourth,eighth,tenth,thirteenth and fifteenth generation seeds of broad bean harvested from the continuous Pb stress in 250 mg·kg -1Pb polluted field as experimental materials,and used potted method in comparison with unpolluted broad bean of same generation,and measured eight physiological indexes related to antioxidant enzyme sys-tem and metabolism,which included the content of chlorophyll,protein,soluble sugar,proline (PRO),malondialdehyde (MDA),and activities of superoxide dismutase (SOD ),glutathione reductase (GR ) and malate dehydrogenase (MDH).The results were as follows: (1) Under long-termed Pb pollution,chlorophyll content related to photosynthesis ability of broad bean between the eighth and thirteenth generation had significant differences (P＜0.05) with control group.(2) Soluble sugar content increased gradually with the duration of stress,and increased to the highest level in the tenth generation and then began to return to normal unpolluted level.Protein content increased from the thirteenth genera-tion.(3) Long-termed Pb pollution stress also produced significant changes in the membrane of broad bean MDA and PRO,which presented the highest contents in the tenth generation; they decreased after the tenth generation and gradually tended to less change after the thirteenth generation.(4) SOD,GR and MDH in the antioxidant enzyme system also showed the de-creasing tendency.GR displayed the largest change,and MDH showed the greatest difference among all experimental and control group at the earliest generations.Through analysis,it can be concluded that under the long-termed continuous heavy metal Pb pollution,the broad bean population has an increasing adaptability to Pb pollution.