【作者】 刘晖；

【导师】 汪良驹；

【作者基本信息】 南京农业大学 ， 果树学， 2005， 硕士

【摘要】 近年来,5-氨基乙酰丙酸（ALA）作为一种新型光动力化合物在医学和农业领域有着广泛的应用前景。本文首先探索了ALA的化学合成,并对水溶液中的5-氨基乙酰丙酸（ALA）在浓度、pH值以及温度等因子影响下的稳定性作了较为系统性的研究,随后对ALA处理是否能提高草莓幼苗的耐盐性及是否能促进盐胁迫下西瓜种子的发芽生长进行了试验。结果表明: 1 5-氨基乙酸的乙酰丙酸合成法 以乙酰丙酸为原料合成ALA,该法方法简单,原料来源广泛易得,毒性低,反应条件温和,操作简便,是一种简易合成5-氨基乙酰丙酸的方法。 2 ALA在水溶液中的稳定性 研究表明,随着ALA水溶液初始浓度、pH以及贮藏温度的升高,ALA的稳定性迅速下降。放于4℃的冰箱中,pH 4.6的缓冲液中ALA最为稳定。因此ALA应采用原药晶体或粉剂形式进行贮藏,密封存放于阴凉干燥处保存。溶液配制时,pH与浓度宜低不宜高,配好的溶液尽量一次用完,并勿与碱性试剂混合使用。 3 ALA对NaCl处理下草莓的生理生化效应 结果表明:在非盐胁迫下,用150mg·L^-1的ALA对幼苗预处理3d后,叶片中CAT、POD活性与净光合速率显著提高;盐胁迫（0.3%NaCl）3d时,未经ALA预处理的幼苗,叶片SOD活性显著下降,O₂^-产生速率显著提高,而ALA预处理组叶片SOD活性升高,O₂^-产生速率明显低于单盐处理:盐胁迫9d时,ALA预处理组叶片CAT、POD活性与净光合速率明显高于未预处理组。以上结果表明,ALA预处理可提高草莓叶片抗氧化酶的活性及增强幼苗的叶片净光合速率,可以从一定程度上提高植株的耐盐性。 4 ALA对盐胁迫下西瓜种子萌发生长的影响 100mmol·L^-1NaCl处理可明显抑制西瓜种子的萌发和幼苗生长,而添加30mg·L^-1外源ALA可明显缓解更高的盐胁迫（125mmol·L^-1） NaCl)的抑制作用。测定的生理指标表明,施用30mg·L^-1ALA可明显提高胚轴胚根的SOD与POD活性,同时显著降低O₂^-产生速率、MDA含量与LOX的活性。添加POD活性抑制剂1g·L^-1AsA,ALA的促进作用被显著抑制。以上结果表明,外源ALA促进盐胁迫下的西瓜种子萌发应该与其能诱导一些抗氧化酶活性,特别是POD活性的提高有关。更多还原

【Abstract】 In recent years, as a new photodynamic compound, it has been proposed that 5-aminolevulinic acid (ALA) has a very important role in medicine and agriculture. For example , it is helpful to diagnose or cure skin and ophthalmic diseases as well as some kinds of cancers, such as bladder cancer, enteron cancer, lung cancer etc. In addition, ALA level can be used as the standard to estimate lead poisoning. In agriculture, ALA may act as insecticide and herbicide; and it can also increase crop yield, enhance resistance of plants to environmental stresses, so it is regarded as a new plant growth regulator and attracting more and more attention. Overseas scholars once reported that when ALA was dissolved, it was found to be unstable, however, the stability properties were not presently well described in the literature. Salt tolerance of cotton, cowpea and spinach could be improved by ALA treatment, but up to now, articles about effects of ALA on fruit plants can not be easily seen yet.In this work, firstly, chemical synthesis of ALA was tested and it’s stability was studied in aqueous solution as a function of concentration, pH and temperature, and then whether ALA treatment could enhance salt tolerance of strawberry and improve germination of watermelon seeds and growth of its seedlings were investigated. The main results were as follows:1 Synthesis of 5-aminolevulinic acid from levulinic acid The route for the synthesis of ALA from levulinic acid was introduced accompanied with mild reaction conditions, low toxicty, simply manipulation and environment friendly. It was a simple way to synthesize ALA.2 Stability of 5-aminolevulinic acid The results showed that the higher the concentration, pH and storage temperature, the faster the degradating rate of ALA, the more unstable ALA was. Therefore, ALA should be stored in the form of original crystal or powder and kept in dry, shady and cool place with package tightly closed. When ALA was dissolved, the pH and concentration of solution should be as low as possible, and used in one time, especially not mixed with alkaline reagents.3 Effects of ALA on strawberry under salt stress Under normal (0 mmol ? L-1 NaCl Conditions, 3 day after 150 mg · L-1 ALA pretreatment, CAT, POD activities and net photosynthetic rate of leaves were significantly increased; 3rd day after 0.3% NaCl treatment, compare to ALA pre-treated ones, in the leaves of non-ALA pre-treated, SOD activity significantly decreased while production rate of O2- increased remarkably; 9th day after NaCl treatment, CAT, POD activities and net photosynthesis rate of ALA pre-treated young plant leaves were significantly higher than that of non-ALA pre-treated. These results indicated that the protection against oxidative damage by higher levels of enzyme activities, and by increase of the photosynthesis, could be involved in the increased salt tolerance observed in strawberry by treatment with 150 mg ? L-1 ALA with NaCl.4 Effects of ALA on watermelon seed germination under salt stress When NaCl concentration was high up to 100 mmol ? L-1, seed germination and seedling growth of watermelon were significantly inhibited. However, treatment with 30 mg ? L-1ALA could promote seed germination and seedling growth even under higher salt stress (125 mmol ·L-1 NaCl ). The results also showed that the activities of SOD and POD in hypocotyls and radicles were increased, while the production rate of O2-, MDA content and LOX activity were decreased remarkably when treated with 30 mg ? L-1 ALA. Adding with AsA (lg · L-1), a POD activity inhibitor, the promotion of ALA was significantly inhibited. These results indicated that the promotion of exogenous ALA treatment on germination under salt stress might be associated with the increased activities of the antioxidases.更多还原