缺镁胁迫对龙眼苗期氮代谢的影响

摘要

The effect of magnesium deficiency on nitrogen metabol ism oflongan (D imocarpus Longana.Lour) seedlings was studied using solution culture. In lea ves with Mg-deficient , the activity of nitrate reductase，the total amount of hydr o lytic amino acids decreased，whereas the total amount of free amino acids increa sed．With the increase in severity of Mg-deficiency，the activities of RN ase and protease in leaves increased markedly．As a result, the degradation of R NA and protein were promoted and their contents reduced; the content of DNA，to a less extent than RNA, also declined．Furthermore, the net rate of O2.- gener a tion increased in Mg-deficiency leaves. Statistics analysis showed tha t the decrease of nucleic acid and protein in Mg-deficient longan leaves were th e comprehensive results of synthesis retardation, degradation aggravation and ac tive oxygen stress.%采用溶液培养方法研究了缺镁胁迫对龙眼苗期氮代谢的影响。结果表明，缺镁胁迫下，龙眼叶片硝酸还原酶(NR)活性下降，游离氨基酸总量增加，水解氨基酸总量减少，蛋白质合成受阻而分解加剧；核酸酶(RNase)活性提高，核糖核酸(RNA)、脱氧核糖核酸（DNA)含量降低，缺镁对RNA的影响比DNA大；活性氧(O2.-)净产生速率增加。统计分析表明，缺镁胁迫下，龙眼核酸和蛋白质含量下降是其合成受阻、分解加剧以及活性氧毒害综合作用的结果。