根瘤菌PP3对水黄皮抗氧化系统应激镍胁迫的影响

Effect of Rhizobium sp. PP3 on the antioxidant system of Pongamia pinnata under nickel stress

摘要:

【背景】 抗氧化系统在植物抵抗逆境胁迫中起着重要作用，而共生根瘤菌是否会影响豆科植物抗氧化防御系统来提高植株抗逆性尚不清楚。【目的】 以耐逆性强的水黄皮(Pongamia pinnata)作为豆科植物代表，开展镍胁迫下的水黄皮快生根瘤菌(Rhizobium sp.) PP3回接水黄皮的盆栽实验，探究根瘤菌共生固氮对豆科植物抗氧化系统应激镍胁迫的影响。【方法】 利用酶联免疫法测定不同处理下水黄皮根、茎、叶中的4种抗氧化酶活性和4种非酶抗氧化剂含量。【结果】 水黄皮植株中的抗氧化酶活性强弱为超氧化物歧化酶(superoxide dismutase, SOD)>过氧化物酶(peroxidase, POD)>过氧化氢酶(catalase, CAT)>谷胱甘肽还原酶(glutathione reductase, GR)，非酶抗氧化剂含量高低为谷胱甘肽(glutathione, GSH)>类黄酮(flavonoids, FLA)>原花青素(oligomeric proantho cyanidins, OPC)>抗坏血酸(ascorbic acid, AsA)；在不施用氮素和40 mg/L Ni²⁺胁迫处理下，接种根瘤菌PP3使水黄皮茎中的POD活性增加61.8%，叶中的SOD、GR和CAT活性增加5.7%、23.6%和36.1%；在施用氮素和40 mg/L Ni²⁺胁迫下，接种根瘤菌PP3使水黄皮植株根中GSH、FLA和OPC含量升高55.9%、61.6%和38.6%，水黄皮植株叶中GSH含量升高14.8%。【结论】 本研究初步揭示了根瘤菌会对水黄皮组织中的抗氧化酶和非酶抗氧化剂产生显著影响，但对不同组织中抗氧化酶和抗氧化剂的影响不同，说明根瘤菌通过介导水黄皮抗氧化防御系统来应激镍胁迫，其在镍污染土壤中强化水黄皮的抗逆性有着重要的作用。

Abstract:

[Background] The antioxidant system plays an important role in plant tolerance to stress, and whether rhizobia affect the antioxidant system of legumes to improve plant tolerance to stress remains unclear. [Objective] Pongamia pinnata with strong stress tolerance was selected as the representative of legumes in this study, and the pot experiments of inoculating Rhizobium sp. PP3 to P. pinnata under nickel stress were performed. [Methods] The activities of four antioxidant enzymes and the content of four non-enzymatic antioxidants in the roots, stems and leaves of P. pinnata in different treatments were determined by the enzyme linked immunosorbent assay. [Results] The activities of antioxidant enzymes in P. pinnata followed the trend of superoxide dismutase (SOD)>peroxidase (POD)>catalase (CAT)>glutathione reductase (GR), and the content non-enzymatic antioxidants was in the order of glutathione (GSH)>flavonoid (FLA)>oligomeric proantho cyanidins (OPC)>ascorbic acid (AsA). In the case of no nitrogen supply and 40 mg/L Ni²⁺ stress, Rhizobium sp. PP3 increased the POD activity in the stems by 61.8%, and the SOD, GR, and CAT activities in the leaves by 5.7%, 23.6%, and 36.1%, respectively. Under the stress of nitrogen and 40 mg/L Ni²⁺, Rhizobium sp. PP3 increased the content of GSH, FLA, and OPC in the roots by 55.9%, 61.6%, and 38.6%, respectively, and the GSH content in the leaves by 14.8% under the stress of 40 mg/L Ni²⁺. [Conclusion] Rhizobia had significant effects on the four antioxidant enzymes and non-enzymatic antioxidants in P. pinnata, while the effects on antioxidant enzymes and antioxidants varied in different tissues. The results indicate that rhizobia regulate the antioxidant system of P. pinnata in response to nickel stress, and they play a role in strengthening the stress tolerance of P. pinnata in the nickel-contaminated soil.