SO2对谷子幼苗根系镉胁迫的缓解作用

以谷子幼苗为材料,采用SO_2衍生物(SO_3~(2-)∶HSO_3~-,3∶1,mmol·L~(-1)/mmol·L~(-1))预处理方式,研究外源SO_2对镉(Cd)致根系毒性的影响。研究发现:250、500μmol·L~(-1)Cd胁迫下,谷子幼苗根生长受到明显抑制,根组织中活性氧(ROS)大量产生,膜脂过氧化增加;与Cd单独处理组相比,用500μmol·L~(-1)SO_2衍生物预处理后,Cd对根系生长的抑制作用减弱,根组织中ROS水平降低,膜脂氧化损伤减轻,谷胱甘肽(GSH)含量提高,过氧化物酶(POD)、谷胱甘肽过氧化物酶(GPX)和谷胱甘肽硫转移酶(GST)等酶活性明显增加。结果表明:一定浓度的SO_2衍生物能够通过上调抗氧化酶系统POD和GPX的活性来有效缓解Cd胁迫造成的谷子根系氧化损伤,并很可能通过维持较高的GSH水平和提高GST活性来增强谷子根系的Cd解毒能力。

Sulfur dioxide alleviates cadmium toxicity in the roots of foxtail millet seedlings

Sulfur is an essential element for plant growth and responses to environmental stress. We show that exogenous SO2 derivates(SO2-3:HSO-3 , 3:1, mmol·L-1/mmol·L-1)alleviated cadmium(Cd)toxicity in foxtail millet(Setaria italica L.)seedlings, mainly focusing on seedling roots. The results show that 250μmol·L-1 and 500μmol·L-1 Cd markedly inhibited root growth, increased the production of reactive oxygen species(ROS), and caused higher levels of lipid peroxidation product malondialdehyde(MDA)in roots of foxtail millet seedling. Compared to Cd treatment alone, pretreatment with 500 μmol·L-1 SO2 derivates weakened the inhibitory effects of Cd on root length and dry weight, and decreased the ROS and MDA levels in millet roots under Cd stress. Moreover, the activities of peroxidase(POD), glutathione peroxidase (GPX)and glutathione S-transferase(GST)as well as glutathione(GSH)contents in SO2 pretreatment groups were also significantly higher than those in Cd treatment alone. These results indicate that activities of POD, GPX and GST enzymes, and increase of GSH content induced by SO2 pretreatment play important roles in plant adaptation to Cd stress. Our results suggest that SO2 could alleviate Cd-induced toxicity through activating antioxidant enzymatic and non-enzymatic components, which could enhance the detoxication capacity in plants.