铝处理下小麦幼苗根系膜脂过氧化作用和质膜微囊ATP酶活性的变化

Changes of lipid peroxidation and ATPases activities of wheat root plasma membrane vesicles under aluminium stress

采用水培的方法研究了Al对小麦（TriticumaestivumL．cvYangmaiNo.5）幼苗的生长、根尖组织膜脂过氧化作用、保护酶的活性和质膜结合酶H+－ATPase、Ca2+－ATPase活性的影响。在实验1中，与对照相比，大于50μmol·L-1的Al处理6d可抑制幼苗根系的伸长，增加根尖组织的细胞电解质渗漏率。随营养液中Al浓度的增加，小麦根／冠比值下降，显示根系生长对Al的反应比地上部分敏感。在实验2中，1000μmol·L-1的Al处理增加很尖组织的电解质渗漏率和MDA含量，降低CAT、APX、SOD的活性，表明Al处理可以加剧小麦根系细胞的膜脂过氧化作用。1000μmol·L-1的Al处理还明显降低根尖细胞质膜微囊H+－ATPase和Ca2+－ATPase的活性与Vmax值，而对Km值的影响较小。这些结果显示过量Al通过破坏细胞的完整性和降低质膜H+－ATPase、Ca2+－ATPase的活性而干扰了小麦幼苗的生长。

Two hydroponic cultures were conducted in investigate the effects 6f aluminium on the growth of wheat (Triticum aestivum L. cv Yangmai No. 5) seedlings,lipid peroxidation of membrane and activities of the protective enzymes,and the activities of H+－ATPase and Ca2+－ATPase associated with plasma membrane of roots tips. In experiment 1,the length of the main root decreased and the rate of electrolyte leakage increased significantly with≥50μmol·L－1 Al for 6 days compared to control. The root/shoot ratio decreased with increasing Al supply,indicating that root growth was clearly more sensitive to Al in solution than shoot growth. In experiment 2, 1000μmol·L－1 Al increased the rate of electrolyte leakage and MDA concentration in root tips,but decreased the activities of CAT,APX and SOD. This showed that lipid peroxidation of membrane had occurred under Al treatment. Treatment with 1000μmol·L－1 Al decreased the activities and Vmax of H+－ATPase and Ca2+－ATPase of plasma membrane vesicles isolated by a continuous density gradient of sucrose centrifugation from the root tips (2~3cm) of wheat,but increased slightly Km values for ATP. The results suggest that Al interfered the growth of wheat seedlings by destroying cell membrane intergrity and decreasing the activities of H+－ATPase and Ca2+－ATPase of plasma membrane.