外源SNP对低温胁迫下甜瓜幼苗生长和氮代谢相关酶的影响

Effect of Exogenous SNP on the Growth and Enzymes Related to Nitrogen Metabolism of Melon Seedlings under Cold Stress

以甜瓜(Cumumis melo L.)幼苗为试验材料,采用基质栽培,对其叶面喷施NO供体硝普钠(sodium nitroprusside,SNP),研究在昼12℃/夜6℃低温胁迫下200μmol/L SNP处理1、3、5、7 d对甜瓜幼苗生长和氮代谢相关酶的影响,探讨外源SNP调控低温胁迫对甜瓜幼苗伤害的可行性。结果显示,随着低温处理时间的延长,甜瓜幼苗生长和氮代谢均受到了一定程度的抑制;经外源SNP处理,幼苗生长指标(叶面积,地上鲜重和地下鲜重)、硝态氮、游离氨基酸、可溶性蛋白含量和硝酸还原酶(NR)、亚硝酸还原酶(NiR)、谷氨酰胺合成酶(GS)、谷氨酸脱氢酶(GDH)、谷氨酸合成酶(GOGAT)和天冬酰胺合成酶(AS)活性显著升高,铵态氮、过氧化氢(H_(2)O_(2))含量和超氧阴离子(O_(2)·-)产生速率显著降低。综上所述,外施200μmol/L的SNP能够有效缓解低温胁迫对甜瓜幼苗的抑制作用,提高其耐低温性,且胁迫时间越长效果越明显。

In order to study the effects of 200μmol/L SNP for 1,3,5,7 d on the growth and the enzymes related to nitrogen metabolism under low temperature stress 12℃/6℃,day/night,and to explore the feasibility of exogenous SNP regulating low temperature stress on melon seedlings.The melon seedlings were used as experimental materials and cultivated by substrate culture method.NO donor sodium nitroprusside(SNP)was sprayed on the leaves.The results showed that with the prolongation of low temperature stress,the seedlings growth and nitrogen metabolismwere inhibited to some extent.After treatment with exogenous SNP,the seedlings growth(leaf area,shoot fresh weight and root fresh weight),the contents of nitrate nitrogen,free amino acid,soluble protein and the activities of key enzymes of nitrogen metabolism(NR,NiR,GS,GDH,GOGAT and AS)were all greatly improved;the contents of ammonium nitrogen,the accumulation of H_(2)O_(2) and the production rate of superoxide anion radical(O_(2)·-)decreased dramatically.In summary,the application of exogenous SNP can effectively alleviate the inhibition of low temperature stress on the growth and nitrogen metabolism,and enhance its low temperature tolerance.The longer the stress,the more obvious the effect.