干旱胁迫及复水对棉花叶片氮代谢的影响

以不同抗旱型棉花品种新陆早7号和新陆早24号幼苗为试材,研究持续干旱胁迫及复水对棉花幼苗叶片氮代谢关键酶活性、可溶性蛋白质、总氮和游离氨基酸含量的影响。结果显示:随着干旱胁迫天数的增加,新陆早7号和新陆早24号硝酸还原酶(NR)活性与对照相比分别降低 51.67%和74.22%;谷氨酰胺合成酶(GS)活性分别降低50.65%和72.95%;谷氨酸合成酶(GOGAT)活性分别降低 43.11%和68.36%;谷氨酸脱氢酶(GDH)活性在处理4d达到最大值;可溶性蛋白质含量分别增加了56.96%和34.12%;总氮含量分别增加了11.39%和8.43%;内肽酶活性分别增加了115.76%和165.06%;铵离子含量分别增加了92.29%和111.56%。干旱胁迫使新陆早7号在胁迫前期游离氨基酸含量增加慢,后期增加快;新陆早24号游离氨基酸含量的变化趋势与新陆早7号则相反。复水后,新陆早7号 NR、GS、GOGAT和GDH等活性恢复较快,内肽酶活性和游离氨基酸、铵离子、可溶性蛋白质和总氮含量下降也较快。试验表明,抗旱棉花品种具有较强的铵离子同化能力,增加渗透调节物质游离氨基酸含量,特别是脯氨酸含量增强其耐旱性。

Effect of Progressive Drought Stress and the Subsequent Re-watering on Leaf Nitrogen Metabolism Cotton Seedlings

Using two genotypes cotton: Xinluzao 7 and Xinluzao 24(drought-resistance and non drought-resistance respectively)materials, some key enzymes activity involving nitrogen metabolism, soluble proteins, total nitrogen, ammonium and free amino acid contents were investigated under progressive drought and re-watering treatment.Progressive drought resulted in NR activity decreased from 51.67% to 74.22%, GS activity from 50.65% to 72.95%, GOGAT activity from 43.11% to 68.36% in Xinluzao 7 and Xinluzao 24 leaves, compared with control, respectively. GDH activity reaches a maximum on the fourth day.whereas endopeptidase activity increased from 115.76% to 165.06%, total nitrogen content from 11.39% to 8.43%, soluble proteins from56.96% to 34.12%, ammonium content from 92.29% to 111.56% in Xinluzao 7 and Xinluzao 24 leaves, compared with control, respectively. Furthermore,the free amino acids content increased slowly during the early stage of drought treatment and then increased rapidly during the latter stage of drought treatment in Xinluzao 7, while the situation was opposite in Xinluzao 24.After re-watering treatment, four indexes recovered more rapidly, including NR activity, GS activity, GOGAT activity and GDH; but the other four indexes decreased more rapidly, including endopeptidase activity, free amino acids content, soluble proteins and total nitrogen content in Xinluzao 7 than Xinluzao 24. These results suggested that cotton with high drought-resistance may has stronger ammonium assimilative capacity, thus it could increased osmotic adjusted substance (especially proline) to improve drought resistance.