两株内生芽孢杆菌对盐胁迫下大豆幼苗超氧化物歧化酶和过氧化物酶活性影响

Two endophytic Bacillus strains from soybean nodules affect superoxide dismutase and peroxidase activities in soybean seedlings under salt stress

摘要:

【背景】盐胁迫环境严重影响大豆幼苗生长，内生菌可提高作物的抗逆性。【目的】探究接种内生枯草芽孢杆菌127和解蛋白芽孢杆菌133对盐胁迫下大豆幼苗体内超氧化物歧化酶(superoxide dismutase，SOD)和过氧化物酶(peroxidase，POD)活性的影响。【方法】以“徐豆20”为实验材料，采用盆栽实验法，设置对照组、盐胁迫组和盐胁迫接菌组，在人工气候培养条件下，用不同NaCl浓度(50、100、150、200、250和300 mmol/L)处理大豆幼苗，并接种不同OD₆₀₀值(OD 0.33、OD0.50和OD0.75)的菌悬液。【结果】培养14 d，接种枯草芽孢杆菌127的菌悬液OD0.33和OD0.75分别在盐浓度300 mmol/L和100 mmol/L时，SOD活性均为1.04 U/g-FW；接种解蛋白芽孢杆菌133的菌悬液OD0.50在盐浓度300 mmol/L胁迫下POD活性最高为7 820 U/(g·min)，对大豆幼苗修复效果较显著。培养28 d，接种枯草芽孢杆菌127的菌悬液OD0.50，在150 mmol/L时SOD活性最高(0.88 U/g-FW)；接种解蛋白芽孢杆菌133的菌悬液OD0.50在100 mmol/L盐胁迫下，POD活性最高[8 300 U/(g·min)]，对大豆幼苗修复效果最显著。【结论】内生枯草芽孢杆菌127和解蛋白芽孢杆菌133发挥作用的最适盐浓度不同，盐胁迫下接种内生菌可使大豆幼苗体内SOD和POD活性不同程度变化，表明接种内生枯草芽孢杆菌127和解蛋白芽孢杆菌133均可提高大豆幼苗的耐盐性，对盐胁迫环境的大豆幼苗具有修复作用。

Abstract:

[Background] Salt stress affects the growth of soybean seedlings, while endophytic bacteria can improve the resistance of soybean seedlings to salt stress. [Objective] This study aims to investigate the effects of endophytic Bacillus subtilis 127 and B. proteolyticus 133 on the activities of superoxide dismutase (SOD) and peroxidase (POD) in soybean seedlings under salt stress. [Methods] Pot experiments were carried out with the soybean variety ‘Xudou 20’ in three groups: control group, salt stress group, and salt stress group with strain inoculation. Under artificial climatic conditions, the soybean seedlings were respectively treated with different concentrations (50, 100, 150, 200, 250 and 300 mmol/L) of NaCl solutions and inoculated with the bacterial suspensions at OD0.33, OD0.50 and OD0.75 (OD₆₀₀ value). [Results] After 14 days, the SOD activity was 1.04 U/g-FW in the soybean seedlings treated with 300 mmol/L or 100 mmol/L NaCl solution and inoculated with B. subtilis 127 suspension at OD0.33 or OD0.75; the POD activity was the highest (7 820 U/(g·min)) in the soybean seedlings treated with 300 mmol/L NaCl solution and inoculated with B. proteolyticus 133 suspension at OD0.50. After 28 days, the SOD activity was the highest (0.88 U/g-FW) in the soybean seedlings treated with 150 mmol/L NaCl solution and inoculated with B. subtilis 127 suspension at OD0.50; the POD activity was the highest (8 300 U/(g·min)) in the soybean seedlings treated with 100 mmol/L NaCl solution and inoculated with B. proteolyticus 133 suspension at OD0.50. [Conclusion] The optimum salt concentrations for endophytes B. subtilis 127 and B. proteolyticus 133 are different, and inoculation of endophytes can increase the SOD and POD activities in soybean seedlings exposed to salt stress. Both B. subtilis 127 and B. proteolyticus 133 can improve the salt tolerance of soybean seedlings.