不同价态铬离子对烟草幼苗抗氧化关键酶和根系活力的影响
材料，采用水培试验法研究不同质量浓度（0.1、0.5、1.0和5.0 mg/L）Cr3+和Cr6+对烟草幼苗相关抗氧化指标的影响，分别测定不同时间（15和30 d）下铬胁迫处理和对照（未添加铬离子处理）幼苗叶片的超氧化物歧化酶（SOD）、过氧化物酶（POD）和多酚氧化酶（PPO）活性、丙二醛（MDA）和脯氨酸（pro）含量及根系活力。【结果】Cr3+处理15 d时，云烟87的POD和PPO活性及红花大金元的SOD活性随着铬离子浓度的增加而升高;Cr3+胁迫30 d及Cr6+分别胁迫15和30 d时，两个烟草品种幼苗叶片的SOD、POD和PPO活性均随着铬离子浓度的增大整体呈先升高后降低的变化趋势，两个品种幼苗叶片酶活性最大时Cr3+浓度为0.5～1.0 mg/L、Cr6+浓度为0.5 mg/L，且铬胁迫对云烟87酶活性的抑制作用总体上强于红花大金元。随着铬离子浓度的增加和胁迫时间的延长，烟草幼苗体内脂质过氧化作用加剧，MDA和pro积累量逐渐增加，高浓度铬离子胁迫下烟苗根系活力较对照显著降低（P<0.05）。【结论】在水培条件下，Cr6+对烟苗抗氧化系统的损伤大于Cr3+;与云烟87相比，红花大金元表现出较强的抗铬性。
关键词： 不同价态铬;烟草;抗氧化关键酶;根系活力
中图分类号： S572.01 文献标志码：A 文章编号：2095-1191（2018）11-2155-07
Effects of chromium ions with different valences on antioxidant key enzymes and root activity of tobacco seedlings
ZHAO Ming-xiang， ZHANG Qi， ZHAO De-guo， XIANG Rong-rong，
ZHU Yong-li， BAO Zhi-juan*
（College of Tobacco Science， Yunnan Agricultural University， Kunming 650201， China）
Abstract：【Objective】In order to provide theoretical basis for the dissection of tolerance mechanism of tobacco under chromium pollution， the influence of chromium ions with different valences on the growth and development of tobacco seedlings was studied. 【Method】Yunyan 87 and Honghuadajinyuan were used as tested tobacco materials. The effects of Cr3+ and Cr6+ with different concentrations（0.1，0.5，1.0 and 5.0 mg/L） on related antioxidant indexes of tobacco seedlings were investigated by using solution culture. The activities of superoxide dismutase（SOD）， peroxidase（POD） and polyphenol oxidase（PPO）， contents of malondialdehyde（MDA） and proline（Pro） in leaves， and root activity of seedlings which were treated with chromium stress and control（without adding chromium ions） were determined at va-rious time points after culturing（15 and 30 d）. 【Result】At 15 d after Cr3 treatment， the POD and PPO activities of Yunyan 87 and SOD activity of Honghuadajinyuan increased with the increase of chromium ions concentration. The activities of SOD， POD and PPO in the seedlings leaves of two tobacco varieties generally increased first and then decreased with the increase of chromium ions concentration when they were treated by Cr3+ stress at 30 d and Cr6+ stress at 15 and 30 d. And under the highest value of enzyme activity of seedlings leaves of the two tobacco varieties， the concentrations of Cr3+ and Cr6+were 0.5-1.0 mg/L and 0.5 mg/L respectively. The inhibitory effect of chromium stress on enzyme activity of Yunyan 87 were stronger than that on Honghuadajinyuan. With the increase of chromium ions concentration and the extension of stress time， the lipid peroxidation was aggravated in tobacco seedlings， the accumulation of MDA and Pro increased gra-dually， and root activity of tobacco seedlings under high concentration of chromium ion stress significantly decreased compared with that of control（P<0.05）. 【Conclusion】In solution culture， Cr6+ has greater damage to the antioxidant system of tobacco seedlings than Cr3+. Honghuadajinyuan shows stronger resistance to chromium than Yunyan 87.