硝酸镧对脐橙叶片抗氧化酶活性的影响

Effects of lanthanum nitrate on antioxidant enzyme activities in leaves of navel orange

为研究稀土元素镧对脐橙叶片抗氧化生理代谢的影响,以2年生纽荷尔脐橙为试验材料,通过叶片喷施浓度为50、150、300 mg/L的硝酸镧溶液,分别于喷施后0、2、4、8、12、24 h采集植株中上部当年生嫩叶,测定超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、谷胱甘肽还原酶(GR)和抗坏血酸氧化酶(APX)的活性,为探明稀土元素对脐橙品质形成提供理论依据。结果表明:不同浓度硝酸镧处理后0~24 h,脐橙叶片SOD活性均呈先升高后降低的趋势,浓度为150 mg/L时活性较高;50 mg/L硝酸镧处理能够有效提升叶片POD活性,且促进了活性峰值的提早出现;50 mg/L硝酸镧处理前期可促进CAT活性的升高,而300 mg/L硝酸镧处理后期可促进CAT活性的升高;叶片GR活性得到明显提高,浓度为300 mg/L时活性最高;叶片APX活性受到明显抑制,150 mg/L硝酸镧处理抑制效果更明显。不同处理时间对抗氧化酶活性的影响较大,3个硝酸镧处理的叶片SOD、GR活性均呈先升高后降低的趋势,均在处理后4 h出现活性高峰;而叶片POD、CAT、APX活性高峰各处理表现不同。硝酸镧处理脐橙叶片促进SOD活性升高、APX活性下降的适宜浓度为150 mg/L,促使POD和CAT活性增加的适宜浓度为50 mg/L,促使GR活性增加的适宜浓度为300 mg/L。综上所述,硝酸镧处理能够提高脐橙叶片的抗氧化能力,抗氧化酶和抗氧化剂共同作用,维持细胞内活性氧产生与消除及氧化还原的动态平衡,进而提高叶片的抗逆性,健康的叶片促进光合与代谢循环,最终提高植株的营养积累。

In order to study the effect of rare earth element lanthanum on the antioxidant physiological metabolism of navel orange leaves,2-year-old ‘Newhall’ navel orange as experimental material,sprayed with lanthanum nitrate solutions of 50 mg/L,150 mg/L and 300 mg/L.The young leaves in the middle and upper parts of the plant were collected at 0 h,2 h,4 h,8 h,12 h and 24 h after spraying,and the activities of antioxidant enzymes such as SOD,POD,CAT,GR and APX were determined,which provided a theoretical basis for exploring the effect of rare earth elements on the quality of navel oranges.The results showed that SOD activity of navel orange leaves increased first and then decreased after 0~24 h of treatment with different concentrations of lanthanum nitrate,and the activity was highers when the concentration was 150 mg/L;50 mg/L lanthanum nitrate treatment can effectively improve the POD activity of leaves,and promote the early emergence of the activity peak;50 mg/L lanthanum nitrate could promote the increase of CAT activity in the early stage,while 300 mg/L lanthanum nitrate could promote the increase of CAT activity in the late stage;the activity of GR in leaves was significantly increased,and the activity was the highest when the concentration was 300 mg/L;the APX activity of leaves was significantly inhibited,and the inhibition effect of 150 mg/L lanthanum nitrate treatment was more obvious.Different treatment time has a great influence on the activity of antioxidant enzymes,the activities of SOD and GR in leaves treated with lanthanum nitrate increased first and then decreased,and the activity peak appeared at 4 h after treatment;the activity of POD,CAT,APX in leaves were different in different treatments.The optimum concentration of lanthanum nitrate to promote the increase of SOD activity and the decrease of APX activity was 150 mg/L,the appropriate concentration to promote the increase of POD andCAT activity was 50 mg/L,and the optimum concentration for increase of GR activity was 300 mg/L.In conclusion,lanthanum nitrate treatment can improve the antioxidant capacity of navel orange leaves,and maintain the dynamic balance of intracellular reactive oxygen species production and elimination and redox through the interaction of antioxidant enzymes and antioxidants,and then improve the stress resistance of leaves.Healthy leaves promote photosynthesis and metabolic cycle,and finally improve plant nutrition accumulation.