吸胀冷害下外源 NO 对紫花苜蓿种子萌发及抗氧化性的影响

摘要

Seeds of Medicago sativa were used to study the effects of 0.1 mmol/L sodium nitroprusside (SNP), as a source of nitric oxide,on seed germination and antioxidant capacity under imbibitional chilling at 4℃.Four treatments:control,chilling,SNP and chilling+SNP were replicated three times.The results indicated that after imbibitional chilling for 12 h and germination at 25℃ for 84 h,the vigor and germination of M.sativa seeds were increased by SNP treatment.The activities of antioxidant enzymes including superoxide dismutase (SOD)and catalase (CAT)increased 149.3% to 60.4% by SNP treatment.The radical clearance rate tended to decline with SNP treatments and chilling for 12,24 and 48 h.At 12 h chilling the radical clearance rate reached a maximum of 97.5%.Imposing exogenous nitric oxide can promote germination,enhance antioxidant enzyme activities and reduce the reactive oxygen damage in M.sativa seed.%用浓度为0．1 mmol／L 外源 NO 供体硝普钠（sodium nitroprusside，SNP）处理4℃吸胀冷害下紫花苜蓿种子，来探讨吸胀冷害下 NO 对紫花苜蓿种子萌发及氧化损伤的影响。试验设计4个处理，分别为 A：对照组（CK）为蒸馏水；B：4℃吸胀冷害组（Chilling）；C：SNP；D：Chilling＋SNP，每个处理重复3次。结果表明：1）紫花苜蓿种子经SNP 处理12 h 转入25℃继续培养84 h 后，Chilling＋SNP 组比 Chilling 组发芽率、活力指数、发芽指数提高了14．37％，34．17％，1．29％。2）4℃吸胀冷害12 h 后，Chilling＋SNP 组同 Chilling 组相比超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性分别提高了149．26％，60．35％，过氧化氢（H2 O2）含量及超氧阴离子（·O2－）产生速率则降低了10．11％，27．61％。3）SNP 对4℃吸胀冷害12，24和48 h 的种子体内羟自由基（·OH）的清除均呈下降趋势， Chilling＋SNP 组的清除率均高出 SNP 组，Chilling＋SNP 组在冷害12 h 时清除率达最大值97．5％。综上所述，施加外源 NO 能促进种子的萌发，提高抗氧化酶活性，降低了活性氧对种子造成的伤害。