铝胁迫对龙眼幼苗蛋白质和核酸含量的影响

Effect of Aluminum Stress on the Content of Protein and Nucleic Acid of Longan (Dimocarpus longan) Seedlings

以苗龄7个月的乌龙岭龙眼实生苗为材料,用营养液培养的方法进行铝胁迫试验。结果表明铝胁迫干扰了龙眼的氮代谢。铝胁迫下,龙眼幼苗叶、根蛋白酶活性显著增加,叶片增加了33.76%～217.30%,根增加了70.45%～167.86%,可溶性蛋白质、热稳定蛋白质和热不稳定蛋白质含量下降,在叶中三者分别下降了16.54%～58.53%、18.29%～64.56%、9.09%～32.87%,在根中三者分别下降了17.84%～34.61%、21.47%～41.59%、12.85%～24.99%,可溶性蛋白质与蛋白酶之间呈显著负相关;铝胁迫下,叶片全N、蛋白质N、铵态N、硝酸还原酶活性下降,非蛋白质N增加,硝态N在低浓度铝胁迫时(≤0.185mmol.L-1)增加,当铝胁迫浓度大于0.185mmol.L-1时则随铝浓度的增加逐渐减少;铝胁迫导致水解氨基酸总量在根中增加,在叶片中下降;铝胁迫下,叶片RNA含量下降了13.10%～61.47%,DNA含量下降了12.61%～41.00%,RNase活性上升了35.62%～63.47%,DNase活性上升了35.57%～183.27%,RNA、DNA分别与RNase活性、DNase活性呈显著的负相关。铝胁迫下蛋白质、核酸含量下降的主要原因有蛋白酶活性升高导致蛋白质水解,RNase、DNase活性的提高,加速了RNA、DNA的分解;RNA、DNA含量减少,使蛋白质合成速率降低;逆境胁迫导致活性氧增加,膜脂过氧化加剧,核酸和蛋白质合成受到抑制。

Using the method of nutritional solution culture, effect of aluminum stress on seven-month Longan （Dimocarpus longan） seedlings was studied. The results showed that aluminum stress disturbed the nitrogen metabolism. Aluminum stress enhanced the activity of protease and reduced content of total soluble protein, heat-stable protein, and heat-unstable protein. The activity of protease in leaves and.roots increased 33.76 % - 217.30 %, 70.45 % - 167.86 % respectively. Soluble protein, heatstable protein, and heat-unstable protein decreased 16.54% - 58.53%, 18.29% - 64.56% ,9.09% - 32.87% in leaves and 17.84% - 34.61% ,21.47% - 41.59%, 12.85% - 24.99% in roots respectively. There was significantly negative correlation between the soluble protein and the activity of protease. Under aluminum stress, the total nitrogen, protein nitrogen, NH46＋ -N, and the activity of nitrate reductase（NR） in leaves decreased, and the non-protein nitrogen increased. NO3 -N increased when the aluminum concentration was lower than 0. 185 mmol· L^- 1, and it decreased when the aluminum concentration was higher than 0. 185 mmol· L^- 1 with increasing the concentration. Aluminum stress reduced the increment of total hydrolytic amino in root and the reduction in leaves. The range of increment was 0.59 % - 11.74 %, and the range of reduction was 0.90 % - 27.55 %. The content of RNA and DNA in leaves decreased 13.10% - 61.47%, 12.61% - 41.00%, and the activity of RNase and DNase increased 35.62% - 63.47%, 35.57% - 183.27% respectively by the aluminum stress. The RNA and DNA negatively correlated with RNase and DNase respectively. The primary causation of the decrease in the protein and nucleic acid of Longan seedlings： the increase of the protease activity induced the proteolysis, with the increment of the RNase and DNase activity, the catabolism of DNA and RNA were accelerated ; and with the reduction of the DNA and RNA content, the velocity of protein synthesis was reduced; the adversity stress induced the increase of AOS, and the acceleration of membrane-lipid peroxidation, and the restraint of protein and nucleic acid synthesis.