甜菜幼苗对氮胁迫及复氮后的生理生化响应

Physiological and Biochemical Responses of Sugar Beet Seedlings to Nitrogen Stress and Nitrogen Resupply

甜菜是我国重要的糖料作物,而氮是影响甜菜产量的重要元素之一。为研究甜菜响应氮胁迫的机制,分析氮胁迫对甜菜生理生化指标的影响,本研究分别在缺氮N0(0 mmol/L)、低氮N1.5(1.5 mmol/L)和复氮处理下,以适氮条件N10(10 mmol/L)为对照,测定0、12、24、48 h及复氮后24、48 h甜菜的根和叶中抗氧化酶活性及生理活性物质的变化。研究结果发现,低氮及缺氮处理导致甜菜幼苗根和叶中过氧化物酶(POD)、超氧化物歧化酶(SOD)和谷胱甘肽转移酶(GST)的活性及脯氨酸(Pro)、丙二醛(MDA)含量的上升,48 h达最大值。其中缺氮N0处理48 h后,与对照N10相比,甜菜幼苗根和叶中POD活性分别增加了214.21%和222.15%,SOD活性分别增加了85.67%和79.17%,GST活性分别增加了683.86%和258.23%;Pro含量分别增加了245.99%和205.57%;MDA含量分别增加了350.20%和129.17%。恢复供氮后,虽然各类指标均有不同程度的下降,但相比对照仍维持在较高的水平。可以推测,甜菜幼苗通过诱导抗氧化酶活性和脯氨酸来应对缺氮和低氮胁迫引发的氧化胁迫和渗透损伤。

Sugar beet is an important sugar crop in China,and nitrogen is one of the important elements affecting the yield of sugar beet.In order to study the mechanism of sugar beet response to nitrogen stress and analyze the effects of nitrogen stress on physiological and biochemical indexes,nitrogen suitable conditions N10(10 mmol/L)was used as control,the changes of antioxidant enzyme activities and physiologically active substances in roots and leaves were measured after 0,12,24,48 h low nitrogen N1.5(1.5 mmol/L)and nitrogen deficiency N0(0 mmol/L),and 24 and 48 h N resupply treatments.The results showed that low nitrogen and N deficiency increased the activities of peroxidase(POD),superoxide dismutase(SOD)and glutathione transferase(GST),and the contents of proline(Pro)and malondialdehyde(MDA),and reached the maximum at 48 h;After 48 h of N0 treatment,the activities of POD,SOD and GST in roots and leaves increased by 214.21%and 222.15%,85.67%and 79.17%,683.86%and 258.23%,and Pro and MDA content in roots and leaves increased by 245.99%and 205.57%,350.20%and 129.17%,respectively,compared with the N10 control;After resuming nitrogen supply,although various indexes decreased in varying degrees,they still remained at a high level compared with the control.It can be speculated that sugar beet seedlings respond to oxidative stress and osmotic damage caused by nitrogen deficiency and low nitrogen stress by inducing antioxidant enzyme activity and proline.