外源NO对铅胁迫下鸡爪大黄种子萌发及幼苗生理特性的影响

Effects of Exogenous NO on Seed Germination and Seedling Physiological Characteristics of Rheum tanguticum Maxim Under Pb Stress

探究重金属Pb2+对鸡爪大黄种子萌发及幼苗生长的影响,以及外源NO对PbCl2溶液胁迫的缓解效应,以蒸馏水浸种为对照,使用不同浓度的PbCl2溶液对鸡爪大黄种子浸种24 h,然后在20℃下培养萌发,继而选择萌发的幼苗在叶面喷施不同浓度SNP溶液。结果表明,随着PbCl2溶液浓度的增大,鸡爪大黄种子的发芽率、发芽势及活力指数均较对照组极显著下降(p<0.01);喷施200 μmol·L^-1的SNP溶液与胁迫而未缓解的ck1组相比,有效降低了幼苗体内丙二醛(MAD)含量、相对电导率(REC),提高了SOD、POD活性、脯氨酸(Pro)含量、叶绿素(a+b)含量。重金属Pb^2+会抑制鸡爪大黄种子的萌发及幼苗的生长,而施加最佳浓度(200 μmol·L^-1)的外源NO可调节抗氧化酶活性和增加渗透调节物质含量,有效保护鸡爪大黄幼苗膜系统的稳定性,进而维持了鸡爪大黄幼苗较高的逆境胁迫耐受性。

To explore the effects of heavy metal Pb2+ on seed germination and seedling growth of Rheum tanguticum and the mitigation effect of exogenous NO on PbCl2 stress, the seeds of R. tanguticum were soaked in distilled water contained different PbCl2 concentrations for culturing and germinating at 20 ℃. Then the germination seedlings were sprayed with SNP solution of different concentrations on the leaf surface. The results showed that with the increase of PbCl2 solution concentration, the germination rate, germination potential and vigor index of R. tanguticum seeds decreased significantly compared with the control group(p<0.01). Compared with the ck1 group without mitigating treatment, the treated group with 200 μmol·L^-1 effectively reduced the content of malondialdehyde(MAD) and relative conductivity(REC) in the seedlings, and increased the activity of SOD, POD and the content of proline(Pro) and chlorophyll(a+b). In a word, the heavy metal Pb^2+ can inhibit the seed germination and the seedlings growth of R. tanguticum, while exogenous NO at the optimal concentration(200 μmol·L^-1) could regulate the activity of antioxidant enzymes and increase the content of osmotic substances, effectively protecting the stability of the membrane system of R. tanguticum, thus maintaining the relatively high tolerance of stress stress in R. tanguticum.